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Fundamentals of Pro/MECHANICA Structure/Thermal
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PRINTING HISTORY
Document No. Date Description
T741-320-01 11/10/01 Initial Printing of Fundamentals of Pro/MECHANICA Structure/Thermal
for Release 2001
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Training Agenda
Fundamentals of Pro/MECHANICA Structure/Thermal
Day 1
Introduction to Pro/MECHANICA
Simplifying Models with Idealizations
Optimizing Models for Analysis
Day 2
Assigning Material Properties
Applying Constraints
Simulating Applied Loads
Day 3
Running and Evaluating Analyses
Analysis and Results: Examples
Day 4
Running Sensitivity and Optimization Studies
Running Analyses
Advanced Exercises
Day 5
Fatigue Advisor
Student Projects
For University Use Only - Commercial Use Prohibited -
Table of Contents
Fundamentals of Pro/MECHANICA Structure/Thermal
INTRODUCTION TO PRO/MECHANICA 1-1
OVERVIEW ...................................................................................................................... 1-2
Structure Simulation...........................................................................................................1-2
RUNNING ANALYSES.................................................................................................... 1-4
Analysis Design Scenario...................................................................................................1-4
Identifying the Design Requirements .................................................................................1-4
Creating the Bracket Design...............................................................................................1-5
Model Idealization..............................................................................................................1-6
Creating the Design Parameters .........................................................................................1-9
Running Sensitivity Studies .............................................................................................1-10
Running Optimization Studies..........................................................................................1-11
USER INTERFACE: INTEGRATED MODE I .............................................................. 1-12
Using the MECHANICA Menu .......................................................................................1-12
Using Toolbar Icons .........................................................................................................1-12
Accessing the Object Sensitive Menu from the MODEL TREE......................................1-13
Using the Icons in the Graphic Window...........................................................................1-14
EXERCISE 1: Create the Bracket Design ........................................................................1-15
EXERCISE 2: Assign the Material Properties .................................................................1-22
EXERCISE 3: Define Constraints ....................................................................................1-23
EXERCISE 4: Define Loads ............................................................................................1-24
EXERCISE 5: Idealize the Model ....................................................................................1-27
EXERCISE 6: Define and Run a Static Analysis .............................................................1-29
EXERCISE 7: Display and Interpret the Results..............................................................1-32
EXERCISE 8: Defining Design Parameters Using Relations ..........................................1-37
EXERCISE 9: Investigating Parameters with Global Sensitivity Studies ........................1-42
EXERCISE 10: Design Optimization...............................................................................1-46
MODULE SUMMARY ................................................................................................... 1-53
SIMPLIFYING MODELS WITH IDEALIZATIONS 2-1
IDEALIZATIONS ............................................................................................................. 2-2
Using Shell Idealizations....................................................................................................2-2
Using Solid Model Idealizations ........................................................................................2-4
For University Use Only - Commercial Use Prohibited -
Creating Rigid Connections ............................................................................................... 2-4
Creating Connections......................................................................................................... 2-5
LABORATORY PRACTICAL..........................................................................................2-6
EXERCISE 1: Using Mass, Spring, and Beam Idealizations............................................. 2-7
EXERCISE 2: Using Shell Idealizations ......................................................................... 2-12
EXERCISE 3: Using Solid Idealizations ......................................................................... 2-18
EXERCISE 4: Using Rigid Connections ......................................................................... 2-27
EXERCISE 5: Using End and Perimeter Welds .............................................................. 2-29
MODULE SUMMARY....................................................................................................2-36
OPTIMIZING MODELS FOR ANALYSIS 3-1
INTEGRATED MODE MODELING ................................................................................3-2
Solid Modeling................................................................................................................... 3-2
Modeling Shells ................................................................................................................. 3-2
Creating Regions................................................................................................................ 3-5
Structural Assemblies ........................................................................................................ 3-6
Modeling in 2-D................................................................................................................. 3-8
LABORATORY PRACTICAL........................................................................................3-10
EXERCISE 1: Suppressing Structurally Insignificant Features....................................... 3-11
EXERCISE 3: Shell Modeling Using Auto Detect .......................................................... 3-21
EXERCISE 4: Creating Regions...................................................................................... 3-23
EXERCISE 5: Creating Volume Regions........................................................................ 3-28
Exercise 6: Structural Assemblies.................................................................................... 3-30
EXERCISE 7: Modeling a 2-D Plane Stress Plate........................................................... 3-32
MODULE SUMMARY....................................................................................................3-34
ASSIGNING MATERIAL PROPERTIES 4-1
BASIC MECHANICS OF MATERIALS ..........................................................................4-2
Young's Modulus ............................................................................................................... 4-2
Poisson's Ratio ................................................................................................................... 4-3
Systems of Units .................................................................................................................4-4
LABORATORY PRACTICAL..........................................................................................4-5
EXERCISE 1: Assign Structural and Thermal Material Properties ................................... 4-5
EXERCISE 2: Adding New Materials to the Library ........................................................ 4-7
EXERCISE 3: Edit and Delete Materials........................................................................... 4-8
MODULE SUMMARY....................................................................................................4-10
APPLYING CONSTRAINTS 5-1
INTRODUCTION ..............................................................................................................5-2
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LABORATORY PRACTICAL ......................................................................................... 5-8
EXERCISE 1: Using Fixed Edge Constraints ....................................................................5-8
EXERCISE 2: Using Point Constraints............................................................................5-10
EXERCISE 3: Using Surface Constraints ........................................................................5-14
EXERCISE 4: Constraining Shell Models .......................................................................5-15
EXERCISE 5: Using Coordinate System Constraints ......................................................5-17
EXERCISE 6: Using Cyclic Symmetry Constraints ........................................................5-19
MODULE SUMMARY ................................................................................................... 5-21
SIMULATING APPLIED LOADS 6-1
INTRODUCTION.............................................................................................................. 6-2
LABORATORY PRACTICAL ......................................................................................... 6-3
EXERCISE1: Applying General Loads..............................................................................6-4
EXERCISE 2: Applying Spatial Load Variations ..............................................................6-8
EXERCISE 3: Varying Load Direction and Magnitude...................................................6-13
EXERCISE 4: Using Pressure and Gravity Loads ...........................................................6-15
EXERCISE 5: Creating Load Distributions .....................................................................6-19
MODULE SUMMARY ................................................................................................... 6-22
RUNNING AND EVALUATING ANALYSES 7-1
INTRODUCTION.............................................................................................................. 7-2
Analysis Options ................................................................................................................7-2
LABORATORY PRACTICAL ......................................................................................... 7-3
EXERCISE 1: Running a Structural Analysis....................................................................7-4
EXERCISE 2: Defining Thermal Analyses......................................................................7-18
EXERCISE 3: Running Combined Analyses ...................................................................7-21
EXERCISE 4: Combining Loads in Results ....................................................................7-25
EXERCISE 5: Comparing MPA to SPA..........................................................................7-29
MODULE SUMMARY ................................................................................................... 7-32
ANALYSIS AND RESULTS: EXAMPLES 8-1
INTRODUCTION.............................................................................................................. 8-2
Analyzing Models ..............................................................................................................8-2
LABORATORY PRACTICAL ......................................................................................... 8-3
EXERCISE 1: Analyzing Roller Mill Bearing Mechanical Properties ..............................8-4
EXERCISE 2: Analyzing Frying Pan Thermal Properties ...............................................8-12
EXERCISE 3: Analyzing a Tuning Fork..........................................................................8-21
MODULE SUMMARY ................................................................................................... 8-25
For University Use Only - Commercial Use Prohibited -
RUNNING SENSITIVITY AND OPTIMIZATION STUDIES 9-1
INTRODUCTION ..............................................................................................................9-2
Running Global Sensitivity Studies ................................................................................... 9-2
Running Local Sensitivity Studies ..................................................................................... 9-2
Running Optimizations ...................................................................................................... 9-3
LABORATORY PRACTICAL..........................................................................................9-4
EXERCISE 1: Optimizing a Belt Clip ............................................................................... 9-5
EXERCISE 2: Running Sensitivity Studies ..................................................................... 9-15
EXERCISE 3: Optimizing the Clip.................................................................................. 9-21
MODULE SUMMARY....................................................................................................9-25
RUNNING ANALYSES 10-1
Model Description ............................................................................................................10-2
ADVANCED EXERCISES 11-1
INTEGRATED MODE CONTACT FUNCTIONALITY ...............................................11-2
Running Contact Analyses............................................................................................... 11-2
Defining Contact Regions ................................................................................................ 11-3
Defining Contact Analysis Measures............................................................................... 11-3
Setting Contact Analysis Options .................................................................................... 11-4
TRANSIENT THERMAL ANALYSIS ...........................................................................11-5
Fundamentals ................................................................................................................... 11-5
LABORATORY PRACTICAL........................................................................................11-8
EXERCISE 1: Creating and Analyzing Spot Welded Sub-Assemblies ........................... 11-9
EXERCISE 2: Contact Problems ................................................................................... 11-14
EXERCISE 3: Running Transient Thermal Analyses.................................................... 11-21
EXERCISE 4: Analyzing Large Deformation ............................................................... 11-26
MODULE SUMMARY..................................................................................................11-36
FATIGUE ADVISOR 12-1
OVERVIEW .....................................................................................................................12-2
LABORATORY PRACTICAL........................................................................................12-4
EXERCISE 1: Piston Fatigue........................................................................................... 12-4
MODULE SUMMARY..................................................................................................12-11
STUDENT PROJECTS 13-1
STUDENT PROJECTS ....................................................................................................13-2
Designing a Flagpole ....................................................................................................... 13-2
Designing a Driveshaft..................................................................................................... 13-3
For University Use Only - Commercial Use Prohibited -
Designing a Wing Spar.....................................................................................................13-3
Designing a Valve Housing..............................................................................................13-5
Designing a Heat Sink ......................................................................................................13-7
Analyzing a Buckling Ring ..............................................................................................13-8
Analyzing a Beverage Can ...............................................................................................13-9
STUDENT PROJECT HINTS....................................................................................... 13-12
USING PTC HELP A-1
DEFINING THE PTC HELP FEATURES....................................................................... A-2
USING THE Pro/ENGINEER ONLINE HELP................................................................ A-2
Defining the PTC Help Table of Contents ........................................................................A-8
TECHNICAL SUPPORT B-1
Locating the Technical Support Web Page ....................................................................... B-2
Opening Technical Support Calls via E-Mail.................................................................... B-2
Opening Technical Support Calls via Telephone .............................................................. B-3
Opening Technical Support Calls via the Web.................................................................. B-3
Sending Data Files to PTC Technical Support .................................................................. B-3
Routing Your Technical Support Calls.............................................................................. B-4
Technical Support Call Priorities ...................................................................................... B-5
Software Performance Report Priorities............................................................................ B-5
Registering for On-Line Support....................................................................................... B-5
Using the Online Services ................................................................................................. B-6
Finding Answers in the Knowledge Base.......................................................................... B-7
CONTACT INFORMATION ........................................................................................... B-9
Technical Support Worldwide Electronic Services ........................................................... B-9
Technical Support Customer Feedback Line..................................................................... B-9
TELEPHONE AND FAX INFORMATION .................................................................. B-10
North America Telephone Information ........................................................................... B-10
Europe Telephone Information........................................................................................ B-11
Asia and Pacific Rim Telephone Information ................................................................. B-15
ELECTRONIC SERVICES ............................................................................................ B-18
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For University Use Only - Commercial Use Prohibited -
For University Use Only - Commercial Use Prohibited -
Page 1-1
Module
Introduction to Pro/MECHANICAIn this module, you learn the basic Pro/MECHANICA structural
simulation process.
Objectives
After completing this module, you will be able to:
• Create a Pro/ENGINEER model for simulation purpose.
• Setup the model for static analysis, including defining the modelidealization, constraints, loads and material properties.
• Define and run the analysis.
• View and interpret the result.
• Optimization the design.
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Page 1-2 Fundamenta ls o f Pro /MECHANICA
NOTES
OVERVIEW
Structure Simulation
An important phase of most design cycles requires engineers to measure
the stress and displacement distribution of new designs. This is necessary
in order to validate the design and ensure it is suitable for its intended use.
To further improve the design, engineers may also need to ascertain the
key variables that control the design. This information is usually used to
optimize designs.
Pro/MECHANICA enables you to validate and optimize your designs by
simulating their responses to various structural load types. Depending on
the purpose of the simulation, the process may vary.
There are two simulation process types:
• Integrated mode – Pro/ENGINEER with integrated limitedPro/MECHANICA analysis features.
• Independent mode – Stand along Pro/MECHANICA withcomprehensive analysis features.
In the Integrated mode, a typical structural simulation consists of the
design validation and optimization phases. These consist of twelve steps.
The first eight steps comprise the Design Validation phase:
1. Create the Model Create the part or assembly that satisfies the
design intent.
2. Idealize the Model Prepare the model for automatic mesh
generation. This includes specifying appropriate idealization types
and any required idealization properties.
3. Set Units and Material Properties Specify the appropriate system
of units and assign material properties.
4. Identify Constraints Define realistic constraints that simulate
how the model will function in the real world.
5. Set Loads Define loads to simulate how the model is loaded in
the real world.
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In t roduct ion to Pro /MECHANICA Page 1-3
NOTES
6. Define the Analysis Define the appropriate analysis type (static,
modal, and so on) based on the required results. You can alsodefine the convergence settings.
7. Run the Analysis Run the defined analysis.
8. View and Interpret the Results You can generate graphs, fringe
plots, and so on to visualize the converged results.
The last four steps comprise the Design Optimization phase:
9. Define the Design Parameters Create Pro/MECHANICA
parameters that specify how the model geometry can change.
10. Run Sensitivity Studies Perform sensitivity studies on the
parameters defined in the previous step. This will help you decide
which parameters have the most influence on the design.
11. Run the Optimization Specify a goal, design constraints, and
parameter ranges that constrain the solution boundaries.
12. Update the Model You can automatically or manually update the
Pro/ENGINEER model.
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Page 1-4 Fundamenta ls o f Pro /MECHANICA
NOTES
RUNNING ANALYSES
This example illustrates a typical structural simulation process as run in
the Integrated mode.
Analysis Design Scenario
Imagine you are an engineer designing large, industrial shelving systems.
These systems are intended for warehouses and must support large loads.
You will use Pro/MECHANICA to model and improve an existing bracket
design. The bracket is used to connect the shelves to the vertical support
rails.
Figure 1 Designing a shelving bracket
Identifying the Design Requirements
The objective is to find a design that is stronger and lighter than the
existing system, yet still easy to assemble. This results in the following
design requirements.
Objective
The design objective is to minimize the bracket mass.
Criteria
The design must support a 20 lbs. (pounds) load applied at a specific
point. The following design criteria must be satisfied:
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In t roduct ion to Pro /MECHANICA Page 1-5
NOTES
• The maximum stress is less 93 N/mm2 (MPa). This maximum
allowable stress is calculated using the tensile yield strength of the
available steel (231 N/mm2) with a safety factor of 2.5.
• The maximum allowable displacement is 0.04 mm. This is necessarybecause a small deformation in the bracket can cause large
displacement at the end of the rack it carries.
• The distance between the two bolt holes (30 mm) and sheet metalthickness (2.5 mm ) must remain fixed. This is necessary due to
assembly constraints.
Creating the Bracket Design
The bracket design is created using Pro/ENGINEER. When constructing
the model, the dimension scheme should reflect the design intent, and also
provide enough design parameters for the design optimization. The
following figure shows the desired design parameters.
Figure 2 Bracket design parameters.
Due to this consideration, the bracket is created using the specific
dimensioning scheme shown in the following figure.
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Page 1-6 Fundamenta ls o f Pro /MECHANICA
NOTES
Note:
Relations can be used to capture the inter-relationship among
the dimensions.
Figure 3: The bracket dimensioning scheme.
Note that the four rounds are created as two separate features: the inner
and outer rounds. This dimensioning scheme provides the flexibility of
altering each feature independently to improve the design.
According to the design constraint, the dimensions of the hole will remain
fixed during the optimization. The detailed instructions can be found in
Exercise 1.
Model Idealization
Like other FEA and GEA simulation packages, Pro/MECHANICA
performs computation at the individual elements. Because
Pro/MECHANICA has extensive auto-meshing capability, most of the
element generation is transparent.
The only required step is to idealize the model. The AutoGEM will
generate the appropriate element based on the model idealization. Various
types of model idealization are available in Pro/MECHANICA to capture
the characteristics of the model. For example, the default solid idealization
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In t roduct ion to Pro /MECHANICA Page 1-7
NOTES
is perfect for simulating “chunky geometry,” and the shell idealization is
suitable for “thin geometry,” such as the bracket.
Idealizing the Bracket as a Shell
To define a shell, you need to define the surface pairs. In this example, the
front and back surface of the bracket model are defined as a surface pair.
The surface pair will be compressed to form the mid-surface, as shown in
the following figure. The detailed instructions can be found in Exercise 5.
Figure 4 Mid-surface compression.
Defining Material Properties
The material of the bracket is steel. The material properties are assigned to
the bracket using the available properties in the library. The detailed
instructions can be found in Exercise 2.
Defining Constraints
In reality, the top and bottom surface of the bracket are welded to other
components. As a result, these surfaces need to be rigidly fixed in
Pro/MECHANICA so that no movement is allowed. The following figure
shows the constrained bracket model. The detailed instructions can be
found in Exercise 3.
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Page 1-8 Fundamenta ls o f Pro /MECHANICA
NOTES
Figure 5 Constrain the bracket surfaces
Defining Loads
In this example, the bracket load must be calculated using realistic loading
condition. In reality, a rack is attached to the bracket using two bolts. A 20
lbs. load is applied to a point as shown in the following figure.
Load
Figure 6 The rack assembly.
Calculating the Bracket Bearing Load
A Free Body Diagram (FBD) can be created as shown in the next figure.
Ay
Ax
By
Bx20 lbs (88.9 N)
Figure 7 The Free Body Diagram of the rack.
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In t roduct ion to Pro /MECHANICA Page 1-9
NOTES
Since the system of equations is indeterminate, the assumption Ay = By is
made. The static calculation yields the following result:
Ax = -889 N; Ay = 44.5 N; Bx = 889 N; By = 44.5 N
The force components of the bracket bearing load are equal and opposite.
The detailed instructions can be found in Exercise 4.
Running the Analysis
The analysis type needs to be chosen depending on the type of problem.
For this problem, a single pass adaptive static analysis is used. The
summary file is used to monitor the progress of the analysis. The detailed
instructions can be found in Exercise 6.
Displaying and Interpreting the Results
The result windows are created to show the stress and displacement of the
model. In this example, three result windows are created:
• An animated fringe plot that shows the von Mises stress of the model.
• An animated fringe plot that shows the displacement of the model.
• An animated fringe plot that shows the principal stress of the model.
• A fringe plot used to dynamically query the stress of the model.
The results show that the design needs to be improved to satisfy the design
requirements. Since most of the part had very low stress, this part is over-
designed. This indicates that further improvement can be made to reduce
weight. The detailed instructions can be found in Exercise 7.
Creating the Design Parameters
Design parameters are variables of the model that can potentially affect
the design objectives. Design parameters can be Pro/ENGINNER
dimensions or model parameters.
In a design optimization, the system changes the variables within a certain
range to find the best values that satisfy the constraints and optimize the
design goal. In this example, there are eight design parameters.
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Page 1-10 Fundamenta ls o f Pro /MECHANICA
NOTES
Maintaining Design Intent using Relations
In Pro/ENGINEER, relations can be created to capture the inter-
relationship among parameters and dimensions.
In Pro/MECHANICA Integrated mode, these relations stay valid and
active in the simulation process. Whenever a design parameter is changed,
the system will re-evaluate the relations and regenerate the model. This
ensure that the model satisfies the design intent.
In this example, the basic shape of the model should be maintained. When
varying the dimension ANG within the allowable range (from 45 degrees
to 90 degrees), the dimension TOP should be adjusted accordingly. To
capture this design intent a relation was created:
top = 62.5 + (45-ang) * 0.5
Due to this relation, when changing the dimension TOP from 45 to 90
degrees, the bracket model maintains its basic shape, as shown in the
following figure.
In Exercise 8, the relation is used to maintain design intent during a
sensitivity study. As a result, eight independent design parameters are
reduced to seven.
Figure 8 Maintain the basic shape of the bracket using relations.
Running Sensitivity Studies
Sensitivity studies are used to determine whether a certain characteristic or
property of the model is sensitive to a design parameter. Specifically, the
system calculates the changes in your model's measures (such as stress and
displacement) when you vary a parameter over a specified range.
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In t roduct ion to Pro /MECHANICA Page 1-11
NOTES
Sensitivity studies can be performed by varying the parameters within a
range (Global sensitivity), or at a specific value (local sensitivity).
Global sensitivity studies serve two primary purposes:
• To rule out the unimportant parameters in the upcoming optimization.
• To determine a good initial value for that parameter to use in theoptimization.
Running Optimization Studies
In an optimization study, the system try to find a set of design parameter
values within the specified ranges that satisfy all of the imposed
constraints, at the same time, try to maximize/minimize certain properties
of the model.
There are several key elements that need to be defined in an optimization
study.
• Goal: A goal is a certain property of the model that will bemaximized/minimized in an optimization analysis.
In this case, the goal is to minimize the mass of the bracket.
• Optimization Constraints: They are constraints that model parametersneed to satisfy.
In this case, the constraints are:
� The maximum von Mises stress is less 93 N/mm2 (MPa).
� The maximum allowable displacement is 0.04 mm.
• Optimization Variables: In an optimization study, the system changesthe variables within a certain range to find the best values that satisfy
the constraints and optimize the goal.
In this case, there are 7 variables shown in Figure 2. The ranges for
these variables can be found in Exercise 10.
Reviewing Optimization Results
The types of results you may want to review are the plots showing von
Mises stress compared to optimization pass. You may also want to review
total mass compared to optimization pass
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USER INTERFACE: INTEGRATED MODE I
In the Integrated mode, there are four ways for you to access the
Pro/MECHANICA commands:
• Commands located under the MECHANICA menu
• Icons in the toolbar located on the right of the graphic pane
• Object sensitive shortcut menu in the MODEL TREE
• Object sensitive shortcut menu accessed from graphic window
Using the MECHANICA Menu
Using Pro/MECHANICA, the user can perform simulation by navigating
the menu structures.
Using Toolbar Icons
You can perform Pro/MECHANICA tasks using icons located on right of
the graphic pane.
The following tables list some commonly used icons.
Table 1 Structural Load Icons
Icon Description
Create a point load.
Create an edge/curve load.
Create a surface load.
Create a centrifugal load.
Create a pressure load.
Create a gravity load.
Table 2 Structural Constraint Icons
Icon Description
Create a point constraint.
Create an edge/curve constraint.
Create a surface constraint.
Create a cyclic symmetry constraint.
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Table 3 Structural Idealization Icons
Icon Description
Define a beam idealization.
Define a shell idealization.
Define a mass idealization.
Define a spring idealization.
Accessing the Object Sensitive Menu from theMODEL TREE
The MODEL TREE displays the entities exist in a simulation model,
including the Simulation Features, Idealizations and Loads/Constraints,
etc.
Figure 9 A typical top-level model tree.
You can expend the junction box to display the detailed list of the entities.
Figure 10 Navigate the Pro/MECHANICA model tree.
Selecting an entity in the MODEL TREE will highlight the entity in the
graphic pane. After an entity is selected in the MODEL TREE, you can
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access the object sensitive shortcut commands by clicking the right mouse
button. The available commands are limited to the selected entity type.
Figure 11 Access the object sensitive menu from the MODEL TREE.
The SELECT_ACTION paradigm streamlines the workflow, increases the
productivity.
Using the Icons in the Graphic Window
Object-sensitive shortcut menu can also be accessed by right-clicking the
icons from the graphic window.
Figure 12 Using the shortcut menu in the graphic window.
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LABORATORY PRACTICAL
Goal
Create a bracket model using Pro/ENGINEER. Set up a static structural
analysis to simulate a loaded bracket. Optimize the bracket design.
EXERCISE 1: Create the Bracket Design
Figure 13 The finished bracket part.
Task 1. Create a new part called BRACKET.
1. Set your working directory to the folder that corresponds to the
name of the current module.
2. Set the environment settings. Click Utilities > Environment. Clear
the Ring Message Bell and Spin Center check boxes. Click OK
to close the dialog-box.
3. Create a new part model:
� Click [New file].
� Select Part.
� Enter [bracket ] as the name.
� Accept the default Use default template.
� Click OK.
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Note:
In Pro/ENGINEER, the models created using the default
templates will contain the information in the template model,
such as the default datum planes and coordinate system.
4. Set up the units.
� From the PART menu. Click Set Up > Units. Select
millimeter Newton Second(mmNs) . Click Set.
� Accept the default Convert Existing Numbers (Same Size).
� Click OK, followed by Close.
Task 2. Create an extruded protrusion as the base feature.
1. From the INSERT pull down menu, click Protrusion > Extrude >
One Side > Done.
2. Select the FRONT datum plane and click OK.
3. Select TOP from the Sket View menu and slect the TOP datum
plane.
4. The system uses the system default feature creation options and
enters the sketcher mode. Close the REFERENCE dialog box.
5. Sketch the section of the base feature as shown in the following
figure.
Note:
The dimensioning scheme captures the design intent, and
provides flexibility for design optimization.
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Figure 14 The base protrusion section.
6. Click [Done] when finish. The system extrudes a defaultdepth and displays the depth value.
7. Select Done.
8. Modify the depth. Double-click the depth dimension and enter
[2.5 ]. Click OK.
9. Switch to the default view. Click View > Default Orientation. The
model should look like the following figure.
10. Save the model.
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Figure 15 The base protrusion.
Task 3. Create one round on the two inner edges shown in the following
figure. The round will have the radius of 5 mm.
Figure 16 Create one round on the two inner edges.
1. Click the [Select Geometry] icon.
2. Select one inner edge. Press <Shift> and select the other edge. You
may need to switch to hidden line mode to see the edges.
3. From the INSERT pull down menu, click Round.
4. A round is created with a temporary value, as shown in the
following figure. You can use the drag handle to dynamically
adjust the round size.
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5. Double click the dimension value. Enter [5].
6. Click the background to implement the changes.
Tips & Techniques
In Pro/ENGINEER to spin, zoom, or pan the model; Press
<CTRL> key and use the three mouse buttons.
Task 4. Create another round on the outer edges, as shown in the
following figure.
Figure 17 Create one round on the outer edges.
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1. Use the same procedures in the previous task to create one round
on the two outer edges.
2. Enter [5] as the round radius.
Task 5. Create and dimension the two bracket holes.
1. From the INSERT pull down menu, click Hole. Accept the default
Straight hole HOLE TYPE option.
2. Enter [12.5 ] for the diameter.
3. Select Thru All for the DEPTH ONE drop down list.
4. Define the hole placement:
� Select the front bracket surface as the PRIMARY REFERENCE.
� Accept the default Linear PLACEMENT TYPE option.
� Select RIGHT and TOP datum plane as the LINEAR
REFERENCE.
� Enter [12.5 ] as the distance from the RIGHT datum plane.
� Enter [0] as the distance from the TOP datum plane.
5. Preview and close the HOLE dialog box by clicking [Done].The hole should appear as shown in the following.
Figure 18 Place a linear hole.
Task 6. Create the second hole as an identical pattern
1. Click Feature > Pattern from the PART menu.
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2. Select the hole you just created as the feature to be patterned.
3. Click Identical > Done.
4. Pick the 0.0 locating dimension as the pattern dimension for the
first direction.
5. Enter [30] for the dimension increment.
6. Click Done from the EXIT menu.
7. Enter [2] for the number of instances.
8. Click Done from the EXIT menu.
9. Save the model. Click [Save]. The model should appear as
the figure shown in the beginning of this exercise.
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EXERCISE 2: Assign the Material Properties
Task 1. Enter Pro/MECHANICA Structure Integrated mode.
1. From the APPLICATIONS pull down menu, click Mechanica.
Click Continue in the UNIT INFO dialog box to confirm your
system of units.
2. Click Structure from the MECHANICA menu.
Task 2. Specify the material properties of the bracket. You will define
the part as steel.
1. Assign the material steel to the bracket. Click Model > Materials.
2. Select STEEL and from MATERIALS IN LIBRARY list, add it to
the MATERIALS IN MODEL list.
3. Select Part From the Assign drop-down list.
4. Select the bracket part and click Done Sel.
5. Close the MATERIALS dialog box.
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EXERCISE 3: Define Constraints
Task 1. Define how the part is constrained. In reality, the bracket is
attached by welding the top and bottom edges to the adjoining hardware.
1. Create an edge constraint. Click [Create an edge/curve
constraint].
2. In the CONSTRAINT dialog box, enter [weld ] as the name of the
constraint.
3. Assign the constraint to a new constraint set.
� In the CONSTRAINT dialog box, click New next to the
MEMBER OF SET to bring up the CONSTRAINT SET dialog
box.
� In the CONSTRAINT SET dialog box, enter [weld ] as the
Constraint set name.
� Click OK to close the CONSTRAINT SET dialog-box.
4. Click the [Select] under the CURVE(S).
5. Select the front top edge and front bottom edge. Click Done Sel.
6. Fix all the DOFs (Degrees of Freedom).
7. Click OK to close the CONSTRAINT dialog-box. The constraint
symbols appear on the model as shown in the following figure.
Figure 19 Constraint the bracket.
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EXERCISE 4: Define Loads
Task 1. Apply the bearing load on the top hole.
1. Create the bearing load. Click [Bearing load].
2. In the BEARING LOAD dialog box, enter [bearing_top ] as the
load name.
3. Assign the load to a new load set.
� In the BEARING LOAD dialog box, click New to bring up the
LOAD SET dialog box.
� In the LOAD SET dialog box, enter [bearing_load ] as the
load set name.
� Click OK to close the LOAD SET dialog box.
4. In the BEARING LOAD dialog box, click [Select] under the
HOLE(S). Select the front bottom edge of the top hole. Click Done
Sel to finish.
Note:
In this case, just like the constraint, the bearing load can beapplied to the surface of the hole.
5. Accept the default option Components from the FORCE drop
down list.
6. Enter [889 ] for the X component, enter [-44.5 ] for the Y
component, keep Z as zero.
7. Click Preview. The system displays the load's distribution, as
shown in the following figure.
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Figure 20 Preview the bearing load.
8. Click OK to finish.
Task 2. Apply the bearing load on the bottom hole.
1. Create another bearing load. Click [Bearing load].
2. In the BEARING LOAD dialog box, enter [bearing_bottom ] as
the load name.
3. Accept the default load set.
4. In the BEARING LOAD dialog box, click [Select] under the
HOLE(S). Select the front bottom edge of the lower hole. Click
Done Sel to finish.
5. Accept the default option Components from the FORCE drop
down list.
6. Enter [-889 ] for the X component, enter [-44.5 ] for the Y
component, keep Z as zero.
7. Click Preview to see the load's distribution.
8. Click OK to finish. The model should appear as shown in the
following figure.
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Figure 21 Apply the bearing load on both holes.
9. Click Done/Return from the LOADS menu.
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EXERCISE 5: Idealize the Model
Task 1. Idealize the model as a shell.
1. Select the model.
2. From the STRC MODEL menu, click Idealizations > Shells >
Midsurfaces > New > Constant.
3. Select the front surface of the model.
4. Click Query Sel and select the back surface.
5. Click Done Sel to finish. Pro/MECHANICA highlights the pairs
in red and yellow.
Task 2. Verify the idealization and visualized the compressed model.
1. Test the mid-surface compression. Click Compress > Shells
only.
2. Click Show Compress to see the created shell. The system
displays only the mid-plane geometry, as shown in the following
figure (displayed in yellow)
Figure 22 The compressed bracket mid-surface.
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Note:
The AutoGEM functionality uses the surface to create
triangular and quadrilateral shell elements. They can be
visualized in the Independent mode.
3. Click Show Original to view the original part (displayed in green).
4. Click Show Both to display both the original part and the
midsurface.
5. Click Done > Done Return > Done Return to finish.
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EXERCISE 6: Define and Run a Static Analysis
Task 1. Define a structural static analysis to determine the stress and
strain caused by the applied loads.
1. Click Analyses from the MEC STRUCT menu to bring up the
ANALYSES dialog box.
2. Create a new static analysis:
� Accept the default Static from m the NEW ANALYSIS type
drop down list.
� Click New. The STATIC ANALYSIS DEFINITION dialog box
appears.
3. In the STATIC ANALYSIS DEFINITION dialog box,
� Enter [bracket_static ] for the name.
� Select weld for the Constraint Set.
� Select bearing_load for the Load Set. Unselect other load set
as necessary.
� On Convergence tab, accept the default Single-Pass
Adaptive.
� Click on the Output tab. Change Plotting Grid to 7.
� Click OK to close the STATIC ANALYSIS DEFINITION dialog-
box.
4. Close the ANALYSES dialog box.
5. Verify that Pro/MECHANICA treat your model as a shell model.
� From the MEC STRUCT menu, click Done/Return.
� From the MECHANICA menu, click Settings and verify that
Use Pairs is checked.
Note:
If you were to clear the Use Pairs check box,
Pro/MECHANICA would treat your model as a solid, which
will take longer to analysis. This setting is automatically
checked when you define pairs.
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Task 2. Run the defined analysis.
1. Click Structure > Run. The RUN dialog box appears.
2. Verify that the analysis BRACKET_STATIC is selected.
3. Click Start.
4. Click Yes when asked "Do you want error detection?".
Note:
Before starting the analysis, it is always helpful to have
Pro/MECHANICA perform error checking on your model.
Task 3. Check to see how the run is progressing by monitoring the
summary file. This file shows you details about each solver pass as the run
progresses.
1. Click Summary. A summary window appears, displaying the
report of the analysis run.
2. Scroll down a little. The report shows the following information:
� Principal System of Units.
� Model type and geometry information.
� Element information.
3. Scroll down a little further the report shows that the solver makes 2
passes.
� In the first pass all of the edges are set to p=3, which is usually
referred to as third order polynomial.
� Based on the results of this pass, the final edge order for all the
edges is determined between three and nine. This polynomial
order distribution is applied to the model and a second pass is
performed.
� Jot down the polynomial order of the second pass __________.
4. Scroll down a little further and review the error estimate. Jot down
the value _______________.
5. Scroll down a little further. The report shows the constraint set and
load set information. Check the values for the total load in X, Y
and Z directions.
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6. Scroll down a little further and review the values of the measures.
Some measures of interest may be the max displacements and
stress components.
Note:
These values can be graphically displayed using the result
interface.
7. Review the Memory and Disk Usage information. You can also
find run time in this section.
8. At the end of the report, it indicates that the run is completed.
9. Click Close to exit the Summary window. Click Done to exit the
RUN dialog box.
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EXERCISE 7: Display and Interpret the Results
Task 1. Create a RESULTS window to look at the distribution of von
Mises stress in the model.
1. Create a RESULT window. Click Results from the MEC STRUCT
menu.
2. Click No when prompted whether you want to save the model. The
result interface is displayed.
3. Create a window to display the stress.
� Click [Insert result window].
� Enter [Bracket_Max_VM ] as the name. The DESIGN STUDY
dialog box appears
� Click the bracket_static\ in the CURRENT DIRECTORY.
� Click Accept to finish.
4. Define the result window contents. In the DEFINE CONTENTS
FOR RESULT WINDOW “MAX_PRINCIPAL” dialog box,
� For the Title, enter [Maximum von Mises ].
� For Quantity, select Stress > Total > Von Mises.
� For Display, select Fringe and clear the Continuous Tone and
Average.
� Select Deform. Accept the Deformed scale 10%.
� Select Animate. Change the number of frames to 16 .
Note:
More frames will result in smoother animation and take longerto generate.
� Select Auto Start and Repeat.
� The dialog box should look like the following figure.
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Figure 23 The stress result window definition dialog box.
5. Click Accept and Show to finish the definition and display the
result window.
6. Use following icons to control the result animation:
� [Stop]; [Play] [Single Step]; [Single Step
Back]
7. Stop the animation when finish.
Task 2. Create a result window to display the displacement by copying
the existing window.
1. Click [Copy window].
2. Enter [Bracket_Displacement ] as the name.
3. Fill out the dialog-box as shown in the following figure.
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Figure 24 The displacement result window definition dialog box.
4. Click Accept to finish.
Task 3. Create a result window to display the Maximum Principal
Stresses by copying the existing window. Maximum Principal Stress
distinguishes tension from compression.
1. Click [Copy window].
2. Enter [Bracket_Principal ] as the name.
3. Enter [Maximum Principal ] as the title.
4. Select Max Principal from the drop-down list.
5. Keep other default settings. Click Accept to finish.
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Task 4. Create a Dynamic Query result window to further investigate
the results.
1. Click [Copy window].
2. Enter [Bracket_vm_query ] as the name.
3. Enter [Von Mises Query ] as the title.
4. Unselect the Animate check box.
5. Keep other default settings. Click Accept to finish.
Task 5. Display the result windows and examine the results.
1. Click [Display Result Windows].
2. In the display result window dialog box, click [Select all],
followed by OK. The system starts to animate all animated
windows.
3. Control individual window separately. Click one window to
activate it. The borders of selected windows should be highlighted
in yellow. Single step the animation.
4. Control multiple windows simultaneously. Press <Shift> and click
all the animated windows.
Note:
Red border indicates an inactivated window.
Task 6. Interpret the result.
1. Jot down the following observations made in the MAX VON
MISES window:
� Locations of the high von Mises stress ____________;
2. Jot down the following observations made in the BRACKET
DISPLACEMENT window:
� Maximum displacement ____________;
� Location of the maximum displacement ____________;
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� Does it satisfy the design requirement? _____________.
3. Stop the animation in all windows. Activate the VON MISES
QUERY window.
4. Determine the von Mises stress and at any point on the model.
� Click Info > Dynamic Query. The QUERY dialog box appears.
� Move the mouse cursor over the fringe plot. Notice that in the
dialog box, the value dynamically updates to show the stress
level at the mouse location.
� Click a location of your interest to place a query tag.
� Click Done to close the QUERY dialog box.
5. Determine the maximum von Mises stress and its location.
� Click Info > Model Max to display the maximum stress
location on the model. Jot down the value ____________.
6. Clear all query tags.
� Click Info > Clear All Query Tags.
� Click Yes when prompted “Do you really want to clear all the
values? ”.
7. Exit the result interface when you finish reviewing the result,
� Click File > Exit Results.
� Choose Yes when prompted to save the result window.
� Enter [Original ] for the name.
� Click Accept to finish.
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EXERCISE 8: Defining Design Parameters UsingRelations
Task 1. Rename the dimensions in Pro/ENGINEER.
1. Return to Pro/ENGINEER. Click Applications > Standard.
2. Display the dimensions. Click Modify and pick on the base feature.
3. Rename the dimensions. From the MODIFY menu, click
DimCosmetics > Symbol.
4. Click the 45 degrees angular dimension, enter [ang ] as the name.
5. Click the 62.5 dimension from TOP datum plane to the tip of the
nose, enter [top ] as the name.
6. Click Info > Switch Dimensions to toggle dimension between the
symbolic name and numerical value. The model should look like
the following figure.
Figure 25 Rename two dimensions
Note:
The initial dimension names may be different due to differentorder of dimension creation.
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Task 2. Create a relation. As the angle changes, the bracket tip must
rotate to maintain the desired part shape. Create a relation that captures
this design intent.
1. From the PART menu, click Relations > Add.
2. Enter the following relations in the message input window:
� Enter [if ang >= 45 & ang <= 90 ]
� Enter [top = 62.5 + (45-ang) * 0.5 ]
� Enter [endif ]
� Click <Return> at a blank line to finish.
3. Pro/ENGINEER creates a file that contains the relations you
entered. To display the file and make any corrections, click Edit
Rel. To close the text editor, click File > Exit.
Note:
The text editor may be different on different platform. You canchange the text editor in the configuration file.
4. Test the relations.
� Click Modify from PART menu and select the base feature.
� Select the 45 degree angular dimension.
� Enter [90] in the message window.
� Click Regenerate from the PART menu. The model should
look like the following figure.
5. Modify the angle back to 45 degrees and regenerate the model.
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Figure 26 Test the relation by modifying the angle.
Task 3. Define the design parameters in Pro/MECHANICA. First, you
add a design parameter to vary the size of the inner fillets.
1. Click Applications > Mechanica > Dsgn Controls > Design
Params > Create. The DESIGN PARAMETERS DEFINITION
dialog box appears.
2. Click Create. The DESIGN PARAMETERS DEFINITION dialog
box appears.
3. In the DESIGN PARAMETERS DEFINITION dialog box:
� Accept the default type Dimension.
� Click Select. Pick on one of the inner round in the model, the
radius dimension with a value of 5 should appear.
� Click the radius dimension.
� Enter [inner_fillets ] for the name of the parameter and
any description you like.
� Define the range. Enter [2.5 ] for the minimum, and [12.5 ] for
the maximum.
4. Click Accept > Done to finish.
5. Test this single design variable. Click Shape Animate from the
DSGN CONTROLS menu.
6. In the shape animate dialog box:
� The inner_fillets check-box is selected by default.
� Change the NUMBER OF INTERVALS to 2.
� Click Animate.
� Press <RETURN> to continue to the next animation step. The
model should change its shape as shown in the following
figure.
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Figure 27 Define a design parameter for the inner round.
7. Click Yes to the message, “Do you want to restore the model to its
original shape? ”.
Task 4. Define more design parameters and animate the shape.
1. Using the procedures in the previous task, create more design
parameters shown in the Figure 2 at the beginning of this chapter.
The name and range of the design parameters can be found in the
following table.
Table 4: The design parameters.
Name Min Current Max
tab_width 25.0 50.0 50.0
tab_top 53.0 62.5 62.5
tab_bottom 26.0 62.5 62.5
mid_curve 46.0 50.0 53.0
ang 45 45 90
outer_fillets 2.5 5 12.5
2. Select Done after creating the parameters.
3. From the DSGN CONTROLS menu, click Shape Animate.
4. In the SHAPE ANIMATE dialog box,
� Select all parameters.
� Change their settings as shown in the following table.
Table 5 Shape Animate settings.
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Parameter Name Settings1: Settings2:
tab_width 50.0 25.0
tab_top 62.5 53.0
tab_bottom 62.5 26.0
mid_curve 53.0 46.0
ang 45 90
inner_fillets 2.5 12.5
outer_fillets 2.5 12.5
� Enter [2] for the NUMBER OF INTERVALS.
� Click Animate.
� Press <RETURN> to continue to the next animation step. The
model should change its shape as shown in the following
figure.
Figure 28 Two design parameter settings.
Note:
Shape Animate simulates what may happen to the geometry
during sensitivity and optimization studies, as the result of
design parameters being updated. It is a good practice to use
shape animate after creating design variables to test the
validity of the geometry.
5. Click Yes to restore the model to its original shape.
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EXERCISE 9: Investigating Parameters with GlobalSensitivity Studies
Task 1. Create a global sensitivity study. Change the inner_fillets radius
within its range (2.5 to 12.5 mm). All other parameters will stay at their
current position during the run.
1. Click Structure > DesignStudies. The DESIGN STUDIES
DEFINITION dialog box appears.
2. In the DESIGN STUDIES DEFINITION dialog box:
� Enter [gs_tab ] for the Study Name.
� Select Global Sensitivity for the type of study.
� For the description, Enter [Sensitivity of the bracket to inner
fillet radius size].
� Verify that BRACKET_STATIC (STATIC) analysis is selected.
� Select INNER_FILLETS parameter and verify that the Start is
Minimum and the End is Maximum.
� Enter [4] for the number of intervals.
� Check the Repeat P-Loop Convergence. The dialog box should
appear as shown in the following figure.
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Figure 29 The DESIGN STUDIES DEFINITION dialog box.
� Click Accept to create the design study.
3. Click Done to close the DESIGN STUDIES dialog box.
Task 2. Run a global sensitivity study.
1. Click Run. The RUN dialog box appears.
2. Verify that GS_TAB (GLOBAL SENSITIVITY) is selected.
3. Reuse elements from an existing study.
� Click Settings. The RUN SETTINGS dialog box appears.
� Select Use Elements from an existing study check-box.
� Click Select and select BRACKET_STATIC.
� Click Accept to close the STUDY DIRECTORY WITH
ELEMENTS dialog box.
� Click Accept to accept and close the RUN SETTINGS dialog
box.
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NOTES
4. Click Start to start running the study.
5. Click Yes for error detection.
6. Click Summary to monitor the study's progress.
7. When the study is complete, click Close > Done.
Task 3. Create a RESULTS WINDOW to graph the von Mises stress vs.
inner_fillet radius.
1. Click Results from the MEC STRUCT menu.
2. Click No when prompted to save the current model. The system
displays the result interface.
3. Create a window to display the stress.
� Click [Insert Result Window].
� Enter [vm_sens ] as the name.
� Click Accept. The DESIGN STUDY dialog box appears
� Click the gs_tab\ in the CURRENT DIRECTORY.
� Click Accept to finish. The DEFINE CONTENTS FOR RESULT
WINDOW “VM_SENS” dialog box appears.
4. Define the result window contents. In the DEFINE CONTENTS
FOR RESULT WINDOW “VM_SENS” dialog box,
� For the TITLE, enter [Max von Mises Stress vs.inner_fillets radius ].
� In the QUANTITY section, click Select next to MEASURE. The
SELECT A MEASURE dialog box appears.
� Scroll down through the list of PREDEFINED measures and
select max_stress_vm from the list.
� Click Accept to return to the DEFINE CONTENTS FOR
RESULT WINDOW “VM_SENS” dialog box.
� In the LOCATION section, click Select next to DESIGN VAR.
� Select INNER_FILLETS followed by Accept.
� Click Accept and Show.
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NOTES
Figure 30 Max VM stress measure vs. inner_fillets dimension graph.
Task 4. Review and interpret the results of a global sensitivity study.
1. The curve quantifies the impact that inner fillets have on stress in
your model.
2. Jot down the INNER_FILLETS value that corresponds to the stress
design constraint __________________. This value can be used as
the initial value of INNER_FILLETS in the optimization.
3. Jot down the range of INNER_FILLETS that von Mises stress is
sensitive to __________________. When there is computer
hardware constraints, this range can be used in the optimization,
instead of using the entire range.
4. Click File > Exit Results when finish.
5. Select No when prompted to save the result windows.
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NOTES
EXERCISE 10: Design Optimization
Task 1. Create the optimization design study. The goal is to minimize
total mass. In addition, there are two limits. Keep the Von Mises stress
below
1. Click Design Studies from the STRUCTURE menu.
2. Click Create in the DESIGN STUDIES dialog box.
3. In the DESIGN STUDIES DEFINITION dialog box, define the name
and type:
� Enter [tab_opt ] for the study name.
� Select Optimization from the TYPE drop down list.
� For the description, Enter [Optimization study for the
bracket ].
4. Set the optimization goal. Verify that GOAL is set to Minimize and
that MEASURE is set to total_mass.
5. Define the optimization limits:
� Click Create underneath LIMITS ON MEASURES. The list of
measures appears.
� Select both max_disp_mag and max_stress_vm from the list.
These are the two limits you want the optimizer to track.
� Click Accept to return to the DESIGN STUDY DEFINITION
dialog box.
� Set the max_disp_mag limit. Accept the default < sign. Enter
[0.04 ] as the limit value.
� Set the max_stress_vm limit. Select the radio button next to
max_stress_vm. Accept the default < sign. Enter [93] as the
limit value.
6. Define the variables.
� In the PARAMETERS section, select all seven buttons under
Parameters. You can use the scroll bar in the PARAMETERS
area to display all the parameters.
� Verify that the MIN is Minimum and the MAX is Maximum for
all parameters.
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NOTES
� Assign the parameters initial values. Enter the INIT value listed
in the following table
Table 6: Set the parameter range and initial values
Parameter Min Init Max
inner_fillets Minimum 3.75 Maximum
outer_fillets Minimum 3.75 Maximum
tab_width Minimum 50.00 Maximum
tab_top Minimum 62.50 Maximum
tab_bottom Minimum 62.50 Maximum
mid_curve Minimum 50.00 Maximum
ang Minimum 45 Maximum
� Enter [2] as the OPTIM CONVERGENCE (%).
� Accept the remaining default values. The dialog box should
look like the following figure.
Figure 31 Optimization design study definition dialog box.
7. Click Accept, followed by Done to finish the optimization design
study definition.
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Task 2. Using the pre-run result, create a result window to display the
graph of von Mises stress vs. Optimization pass. The graph shows how the
stress was reduced during the optimization.
1. Click Results from the MEC STRUCT menu.
2. Click No when prompted to save the current model. The system
displays the result interface.
3. Create a result window to display the graph of von Mises stress vs.
optimization pass:
� Click [Insert Result Window].
� Enter [vm_history ] as the name.
� Click Accept. The DESIGN STUDY dialog box appears.
� The pre-run design study result is in the subdirectory
Fund_structure_320/Integrated/results , navigate to
the directory, select Results from the list and click Change
Directory.
� Double-click on tab, select tab_opt from the list of studies.
� Click Accept to finish. The DEFINE CONTENTS FOR RESULT
WINDOW “VM_HISTORY” dialog box appears.
4. Define the result window contents. In the DEFINE CONTENTS
FOR RESULT WINDOW “VM_ HISTORY” dialog box,
� Enter [Max Von Mises Stress vs. Optimization
Pass ] for the title.
� In the QUANTITY section, select Measure from the list.
� Click Select next to MEASURE. The SELECT A MEASURE
dialog box appears.
� Scroll down through the list of PREDEFINED measures and
select max_stress_vm from the list.
� Click Accept to return to the DEFINE CONTENTS FOR
RESULT WINDOW “VM_ HISTORY” dialog box.
� Click Accept and Show.
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NOTES
Task 3. Create a RESULT window to displays the graph of mass vs.
optimization pass by copying an existing window definition
1. Click [Copy window]. The COPY RESULT WINDOW:
“VM_HISTORY” appears.
1. Enter [mass_history ] as the name the new window followed by
Accept. The DEFINE CONTENTS FOR RESULT WINDOW
“MASS_HISTORY” dialog box appears.
2. Define the result window contents. In the DEFINE CONTENTS
FOR RESULT WINDOW “MASS _ HISTORY” dialog box,
� Enter [Total Mass vs. Optimization Pass ] for the
title.
� In the QUANTITY section, select Measure from the list.
� Click Select next to MEASURE. The SELECT A MEASURE
dialog box appears.
� Scroll down through the list of PREDEFINED measures and
select total_mass from the list.
� Click Accept to return to the DEFINE CONTENTS FOR
RESULT WINDOW “MASS _ HISTORY” dialog box.
� Click Accept and Show.
3. Jot down the following information:
� Initial mass _______________;
� Final mass ________________.
4. Exit the result interface when you finish reviewing the result,
� Click File > Exit Results.
� Choose Yes when prompted to save the result window.
� Enter [bracket_optimization ] for the name.
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Figure 32 The optimization graphs.
Task 4. Replay the optimization process and update the design.
1. Change the working directory to where the optimization design
study is located.
� Click File > Working Directory.
� Navigate to the RESULTS sub-directory.
� Click OK.
2. From the MEC STRUCT menu, click Model > Dsgn Controls >
Optimize Hist > Search Study.
5. Animate the optimization process.
� Select the BRACKET_OPT.
� Press <Enter> when prompted to review the next step.
� Repeat to advance to the next step.
6. Update the design parameters so that the model remains at the
optimized state. Press <Enter> when prompted “Leave the model
at the optimized shape?”. The model should look like the
following figure.
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NOTES
Figure 33 The optimized bracket model.
Task 5. Create a results window to show the von Mises Stress fringe
plot of the optimized model.
1. Change the working directory back to
FUND_STRUCTURE_320/INTEGRATED.
� Click File > Working Directory.
� Navigate to the FUND_STRUCTURE_320/INTEGRATED sub-
directory.
� Click OK.
2. From the MEC STRUCT menu, click Results.
3. Click No when prompted whether you want to save the model. The
result interface is displayed.
4. Create a window to display the stress.
� Click [Insert Result Window].
� Enter [vm_final ] as the name. The DESIGN STUDY dialog
box appears
� Click the bracket_opt\ in the CURRENT DIRECTORY.
� Click Accept to finish.
5. Define the result window contents. In the DEFINE CONTENTS
FOR RESULT WINDOW “VM_FINAL” dialog box,
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� For the Title, enter [Von Mises Stress – Optimized
Shape].
� For Quantity, select Stress > Total > Von Mises.
� For Display, select Fringe. Clear Continuous Tone and
Average.
� Select Deformed and accept the Deformed scale 10%.
� Select Animate. Change the number of frames to 16 .
� Select Auto Start and Reverse.
� Click Accept and Show to finish and display the RESULTS
window.
6. Jot down the following information:
� Maximum von Mises stress ________________;
� Maximum Displacement __________________.
7. Calculate how much the mass has been reduced ___________.
8. Exit the result interface when you finish reviewing the result,
� Click File > Exit Results.
� Choose Yes when prompted to save the result window.
� Enter [final ] for the name.
9. Switch to the standard application. Save and erase the model.
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NOTES
MODULE SUMMARY
You have learned:
• How to setup the model appropriately for static analysis, includingdefining the model idealization, constraints, loads and material
properties.
• Define and run the analysis.
• View and interpret the result.
• Optimization the design.
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Page 2-1
Module
Simplifying Models with IdealizationsIn this module, you learn how to use idealizations in
Pro/MECHANICA. Idealizations are the mathematical
approximation of your model's geometry that Pro/MECHANICA
uses to simulate the behavior of your design.
Objectives
After completing this module, you will be able to:
• Describe the purpose of using idealizations to simplify yourdesigns.
• Describe the types and applications of idealizations.
• Define rigid connection idealizations.
• Define end- and perimeter-weld idealizations.
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IDEALIZATIONS
You can use idealizations as simplifications of your designs when running
analyses. During analysis, Pro/MECHANICA calculates stress and other
values in each model idealization. There are different types of
idealizations available in Pro/MECHANICA. It is important to understand
the following idealization types and how they affect the results you will
get for any given analysis.
• Mass- Used to represent a concentrated or point mass without aspecified shape (Structure only).
• Spring- Used to represent a linear elastic (six degrees-of-freedom)spring connection (Structure only).
• Beam- Used to model a structure that is relatively long compared to itsthickness and width, with a constant cross section.
• Shell- Used to model a structure with a constant thickness which isthin compared to its length and width.
• Solid- Used to model a structure that is as thick and wide as it is long.Its cross section and thickness can vary.
When deciding on which idealization to use, consider the structure you are
modeling and how that structure behaves, rather than the geometry. This
will help you select the type of element for your model.
Using Shell Idealizations
You would typically use a shell model when your part is relatively thin
compared to its length and width. Shells are 3-D idealizations that have
length, width, and thickness. Shell models run faster and require less disk
space than solid models – without sacrificing accuracy.
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NOTES
To meet Pro/MECHANICA's criteria for shell models, your part must
have a constant or multi-constant thickness. In other words, you can not
shell model a tapered part, but your part can have multiple constant
thickness areas. The thickness of the shell idealization is always
distributed symmetrically about the surface on which it is placed. For this
reason, it is important that this surface actually represent the “mid-plane”
of the model.
Creating the Mid-Surface
By default, Pro/MECHANICA treats all Integrated Mode models as solid
models. You can direct Pro/MECHANICA to treat your part as a shell
model by defining “mid-plane” surfaces. The focus of this chapter is to
teach you how to “compress” a solid model to a shell model.
To model your part as a shell model, you must use the following
procedure:
1. Define Shell Pairs – The first step is to define ‘pairs’ of solid
surfaces which will be ‘compressed’ to form the ‘mid-surface’ of
the model. A surface/shell pair consists of two or more parallel
surfaces on opposite sides of a volume.
2. Test the Pairs Compression – Once the pairs have been defined,
Pro/MECHANICA attempts to compress all the pairs to a
continuous surface model representing the ‘middle’ of the part.
You should review this mid-surface model to ensure that it has
compressed to the desired form, i.e. you should ‘test the
compression’.
3. Verify the Use Pairs Setting – To ensure that Pro/MECHANICA
treats the model as a shell, you should verify that the Use Pairs
setting is selected.
Creating Shells
It is important to note that the procedure described above is used only to
define the mid-surfaces on which shell elements will be placed. In the
Integrated Pro/Mechanica interface these shell elements are not manually
created by the user. Rather, they are automatically created when an
analysis is run. In Integrated Mode, all elements are created by the
Mechanica auto-mesher, known as the AutoGEM utility. The most
important difference between Integrated Mode and Independent Mode is
that elements can be manually created in the Independent Mode.
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Using Solid Model Idealizations
A solid model is a part that you model using solid elements like
tetrahedral, bricks, or wedges. In Integrated Mode, Pro/MECHANICA
uses only tetrahedrals for solid modeling. You use solid modeling when
your part is as thick and wide as it is long. Your part's thickness, however,
can vary non-uniformly.
There are three different shapes a solid element can take. The three
different solids can be remembered by the number and type of faces that it
takes to define them.
Table 1 Solid element types.
Solid
Type
Description
Brick Two opposite
Quad faces, (total
of 8 points)
Wedge Two opposite Tri
faces, (total of
points)
Tetra One Tri faces and
one opposite point,
(total of points)
Creating Rigid Connections
A rigid connection connects geometric entities, such as surfaces, curves
and points, so that they remain rigidly connected during an analysis. When
you connect entities in this way,
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NOTES
• They move together as if part of a single rigid body
• They do not deform, but the rigid body can move as a whole.
Because Pro/MECHANICA uses linear constraint equations to enforce the
rigid rotations, rather than equations with trigonometric functions (such as
sine and cosine), you should use rigid connections only for small rotation
angles of rigidly connected entities. Use rigid connections in this way,
even if you intend to use them in a large deformation analysis.
Pro/MECHANICA supports rigid connections for 3-D models only.
Creating Connections
A connection is the point of contact between two or more parts or
subassemblies. In Pro/MECHANICA, you can use two kinds of
connections—end welds and perimeter welds.
End Welds
Use end welds in assembly models to connect plates. Plates can be curved
and placed at oblique or right angles, such as T or L configurations. Using
the end weld, the shell mesh from one plate is extended to meet the mesh
from the base plate.
You can use end welds to join:
• Two thin wall components at a right angle.
• Two thin wall components at an oblique angle.
• Two offset thin wall components mated at a right angle with a gapbetween the compressed surfaces of the components.
• Two offset thin wall components mated at an oblique angle with nocontact between the components.
Perimeter Welds
Use perimeter welds in assembly models to connect parallel plates, which
may be curved, along the perimeter of another plate. During mesh
generation, a sequence of surfaces is automatically created to connect theselected edges of the top plate to the base plate. Pro/MECHANICA creates
shell elements on the selected surfaces. A series of welds on one or more
of the perimeter edges of the top plate connects it to the base plate. In this
case, the components are touching. The resulting compressed surfaces,
however, are parallel to one another and do not touch. For this type of
geometry, you should use a perimeter weld to connect the two plates.
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NOTES
LABORATORY PRACTICAL
Goal
To use idealizations to simplify a design.
Method
In Exercise 1 you examine mass, spring and beam idealizations. The
model you will be working on is a truss. Since you will be defining the
beam section properties (I-beam, solid circle, etc.) in Pro/MECHANICA,all you need to create for the geometry is the datum curve framework to
set up beam idealizations.
In Exercise 2 you learn how to direct Pro/MECHANICA to treat your part
as a shell model by automatically defining mid-plane surfaces. You create
the two intersecting pipes.
In Exercise 3 you learn how the Integrated Mode automatically meshes
solid models using the T-Bracket.
In Exercise 4 you will learn how to define rigid connections.
In Exercise 5 you will learn how to create end and perimeter welds.
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NOTES
EXERCISE 1: Using Mass, Spring, and BeamIdealizations
Figure 1 A truss structure made up of datum curves.
Task 1. Create the truss structure.
4. Set your working directory to the folder that corresponds to the
name of the current module.
5. Click File > New.
6. Select Part from the dialog box. Enter [truss ] for the part name.
7. Leave the Use Default Template check box selected. The new
part will have three defaults, datum planes, and a csys.
8. Turn off the spin center and bell if necessary. Click Utilities >
Environment. Clear both the spin center and ring message bell
check boxes.
9. Change units from Pro/Engineer default to mm N s. Click Setup >
Units. Select mm Ns and click Set. Accept Same Size option.
Click OK > Close.
10. Create a sketched datum curve.
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� Click [Insert a sketched datum curve] on the right. Select
the default.
� Select the FRONT datum plane, click OK.
� Close the REFERENCES dialog box.
11. Sketch the datum curve as shown in the following figure.
Figure 2 Sketch the datum curves.
Note:
With Intent Manager, constraints are established while you
sketch. In addition, your sketch automatically snaps to the
references you specified. When you finish sketching, Intent
Manager creates a default dimensioning scheme. To override
the default weak dimensions, simply create new dimensions.
12. Click [Done] to finish and then click OK.
Task 2. Create the beams.
1. Enter Pro/MECHANICA Structure. Click Mechanica from the
APPLICATION menu.
2. Click Continue in the UNIT INFO window. Click Structure.
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NOTES
3. Accept the default Model from the MEC STRUCT menu. Click
Idealizations > Beams > New. The BEAM DEFINITION dialog
box appears.
4. Enter [hollow_tube ] for the name.
5. Select Edge/Curve from REFERENCE drop-down menu. Click
[Select]. Select all the curves in the model. Click Done Sel.
6. Click More next to the MATERIAL. MATERIALS dialog box
appears. Select Steel. Click the right arrows to assign to the model.
Click OK.
7. From the Y DIRECTION menu, select Vector in WCS and enter
[0,0,1 ] respectively for the X, Y and Z directions.
8. Click More next to SECTION. The BEAM SECTION dialog box
appears. Click New. The BEAM SECTION DEFINITION dialog
box appears.
9. Select Hollow Circle from SECTION TYPE drop-down list.
10. Enter [12.5 ] for R and [8.75 ] for Ri. Click Review > OK.
11. Click OK > OK. Do not define Beam Orientation and Beam
Release. They will be discussed later. Click OK.
12. Click Done/Return.
13. Click View > Default Orientation. Notice that Beam Section icons
appear at intervals along each beam. This gives you a visual idea
of the size and shape of the hollow tubing.
Mass and Spring Idealizations
Task 3. Attach a weight (mass) to the tip of the truss and model a
flexible support (spring) attached at the center of the truss and the ground.
Note:
These Mass and Spring idealizations are placed at datum
points on your model. You will create a datum point inPro/MECHANICA.
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NOTES
1. Switch to the front view. Click the Saved Views icon followed by
Front.
2. Create a datum point at the right most vertex of your model. Click
[Create a datum point]. Click On Vertex.
3. Click the vertex on the top right of the truss, corresponds to the
PNT0 shown in the following figure, followed by Done Sel >
Done.
4. Create another datum point, PNT1, using on vertex as shown in the
following figure.
Figure 3 The Truss Model
5. Create a mass at the point that you just created. Click
Idealizations > Masses > New.
6. Accept the default name. Click [Select] and select PNT0
followed by Done Sel. Accept the default type. Enter [100 ] as the
mass followed by OK. The Mass icon appears.
7. Create a spring between PNT1 and the ground. Click Springs >
New.
8. Accept the default name. Select To Ground from the Type drop-
down list. Click [Select] and select PNT1, followed by Done
Sel.
9. Click More next to PROPERTIES. Click New to create a spring
property.
10. In the SPRING PROPERTIES DEFINITION dialog box, enter the
[10, 1000, 10] for Kxx, Kyy and Kzz respectively and accept other
defaults.
11. Click OK > OK > OK. The spring icon appears.
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NOTES
Figure 4 The truss model with beam, mass and spring idealizations.
Task 4. Blank the idealization icon display.
1. Click Simulation Display from the VIEW pull-down menu. Then
click Visibilities.
2. Clear Beam Sections, Masses and Springs, followed by OK. The
model now is ready for applying load and defining analyses.
3. Select Done > Return from the IDEALIZATIONS menu.
4. Save and erase the model when finished.
Note:
The model is displayed without the Beam Section icons since
it may interfere with visibility when you are working on a
complex model. Adjust these as necessary for ease of use inPro/MECHANICA.
Tips & Techniques
Items, such as Loads/ Constraints, Simulation features are
displayed together with Pro/ENGINEER features in the Model
Tree. You can use the Model Tree as a “shortcut” to
manipulate these items. Right-click an object in the Model
Tree. A pop-up menu will appear. You can then manipulate
these items.
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NOTES
EXERCISE 2: Using Shell Idealizations
Figure 5 Idealize the intersecting pipe as a shell.
Task 1. Create two intersecting pipes.
1. Click File > New.
2. Select Part. Enter [pipes ] for the part name. Use the default
template.
3. Change units from Pro Engineer default to mm N s. Click Setup >
Units. Select mm Ns and click Set. Accept Same Size option.
Click OK > Close.
4. Create a solid protrusion to represent the first pipe.
� Click Insert > Protrusion > Extrude > Done.
� Select the TOP datum plane and click Okay. Select Default
from SKET VIEW.
5. Sketch a circle that is 250 mm in diameter. For a blind depth, enter
[750 ] mm.
6. Change the default attribute to both side protrusion.
� Right-click the protrusion in the MODEL TREE and choose
Redefine.
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NOTES
� Double-click the Attribute. Select Both Side > Done > Done.
Accept the depth value, followed by OK. The protrusion should
appear as shown in the following figure.
Figure 6 Finished base protrusion.
7. Repeat the preceding procedures to create a second solid
protrusion with 200m diameter and 750mm depth to represent the
second pipe. Use FRONT as the sketching plane. Use Both Side
option.
8. Insert a round at the intersection of the two cylinders with a radius
of 25 mm.
9. Click Insert > Round.
10. Click Simple > Done.
11. Click Done to accept the defaults Constant and Edge Chain.
Click the two edges that represent the intersection of the two
cylinders, followed by Done Sel. Enter [25] as the radius.
12. Click OK to finish. The model should appear as shown in the
following figure.
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Figure 7 Unshelled pipe.
13. Shell the pipes with a thickness of 6.25. Click Insert > Shell.
14. Select the four pipe ends as the surfaces to remove, as shown in the
previous figure. Click Done Sel > Done Refs.
15. Enter [6.25 ] as the thickness. Click OK to complete the shell.
16. Save the model.
Task 2. Create the mid-surface of the shell model.
1. Enter Pro/MECHANICA. Click Applications > Mechanica. Read
the unit information and click Continue.
2. Click Structure > Model > Idealizations > Shells.
3. Turn off the Datum Planes, Axes, and Coordinate Systems by
toggling the icons on the toolbar.
4. Shade the model using the icons in the toolbar.
5. Click Midsurfaces > Auto Detect.
Surfaces to remove
Hidden Surfaces to
remove
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NOTES
Note:
Pro/MECHANICA highlights one set of surfaces in red and
the opposing surfaces in yellow. The red surface acts as a point
of reference for the pair. Pro/MECHANICA uses this surface
as a view point when determining which opposing surfaces in
the model are part of the pair.
6. From the SHELLS menu, click Compress > Shells only > Show
Compress to test the mid-plane compression. The pairs get
compressed and display in yellow as shown in the following
figure.
7. Click Done/Return > Done/Return > Done/Return.
Figure 8 Compressed pipe.
Create Shells
Now you will examine the shell element mesh in Independent Mode. This
is NOT a require step. Normally, you will set up an analysis and then run
it without ever leaving the Integrated interface. When you run an analysis
in Integrated Mode, the AutoGEM auto mesher will create the elements.
Task 3. Transfer to Independent mode to manually AutoGEM.
1. From the MECHANICA menu, click Settings.
2. Notice that the Use Pairs option is turned on automatically, as a
result of shell idealization. This setting tells Pro/MECHANICA to
place shell elements on the midsurfaces you just defined. If you
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NOTES
want to model this part as a solid instead, you would turn off this
setting.
3. Click Indep MEC > Structure to quit Integrated mode, and enter
the Independent mode STRUCTURE.
4. Confirm to exit Pro/ENGINEER. Click OK to close the
information window.
5. Save the model with a new name when prompted. Enter
[pipes_2 ] as a new name. Click Accept.
6. Change the model view to isometric. Click View > Iso > Done.
7. When the model displays, click Settings from the DISPLAY pull
down menu to change the settings.
8. Select the DISPLAY TYPE Smooth Shade, the DISPLAY
QUALITY Fine, and the SHADE Geometry. Select Display
Edges, accept other defaults and click Accept.
9. Notice that only the midsurface geometry was imported into
Independent Pro/MECHANICA.
Task 4. AutoGEM the midsurface.
1. Click Model > Elements > AutoGEM > Surface > All, followed
by <Return>.
2. When you mesh the model, AutoGEM creates shell elements. The
type of idealization determines the types of elements that
AutoGEM will create.
3. Read the SUMMARY window and click OK to finish.
4. Change to an isometric view. Click View > Iso > Done.
5. Adjust the element display settings. Click Display > Settings
from the DISPLAY menu:
� Shade the elements. Select Smooth Shade from the DISPLAY
TYPE drop-down list.
� Select Elements from the SHADE drop-down list.
� Select Shrink All Elements check box with a factor of 0.2 .
� Click Accept
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NOTES
6. Visually examine the model. The model should look like the
following figure.
Figure 9 The meshed pipe part.
Task 5. Verify the mid-surface thickness. It is automatically defined
during the shell idealization in the Integrated mode.
1. To verify that the correct part thickness was automatically
assigned, click Edit > Property > Shell Property > Surface.
2. Click the surface mesh lines of any surface. Note that the shell
thickness properties have been assigned.
3. Click Cancel to finish, followed by <Return>.
4. Exit Pro/MECHANICA. Click File > Quit. Answer Yes to
whether or not you want to quit, and No to the saving the model
prompt.
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EXERCISE 3: Using Solid Idealizations
Figure 10 The finished geometry.
Task 1. Create the base for the t_bracket.
1. Start a new Pro/ENGINEER session. Set the current working
directory as directed by your instructor.
2. Create a part called t_bracket. Click File > New. Enter
[t_bracket ] for the name. Use the default template.
3. Set mm Ns as units. Click Set Up > Units. Select mm Ns. Click
Set > Same Size > OK > Close.
4. Create the base of the T-Bracket using a thin protrusion. Click
Insert > Thin Protrusion > Both Sides > Done.
5. Pick FRONT as the sketching plane and click Okay. Pick TOP as a
horizontal reference, and select the TOP datum plane.
6. Sketch the T-Bracket's base as shown in the following figure.
Since the base is symmetrical about DTM1, use a vertical
centerline on the RIGHT datum plane.
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NOTES
Figure 11 Sketch a horizontal line symmetric about RIGHT.
7. Click [Done].
8. Select Both from the THIN OPT menu. Enter [25] for the thin
feature width.
9. Click Blind > Done in the SPEC TO menu. Enter [250 ] as the
extrusion depth.
10. Click OK to complete the feature.
Task 2. Task 2. Create the rib for the t_bracket.
1. The vertical rib can also be created as a thin protrusion. Click
Insert > Thin Protrusion > Extrude > Both Sides > Done.
2. Click Use Prev, followed by Okay.
3. Select RIGHT and the top surface of the first protrusion as
references.
4. Sketch the t-bracket's vertical rib as shown in the following figure.
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Figure 12 Sketch a vertical line on RIGHT.
5. Click [Done].
6. Click Both from the THIN OPT menu. Enter [25] for the thin
feature width in the message window.
7. Click Blind > Done in the SPEC TO menu. Enter [250 ] as the
extrusion depth.
8. Click View > Default > Preview. The part should appear as shown
in the following figure. Click OK to complete the feature.
Figure 13 The finished T-bracket geometry.
9. Save the model. Click File > Save, followed by <Enter>
Task 3. Task 3. Transfer the part to the Independent mode and
manually AutoGEM it.
Note:
This optional step is performed to illustrate the meshed model.
1. Start Independent session of Pro/MECHANICA. ClickApplications > Mechanica
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NOTES
2. Click Continue in the UNIT INFO window. Click Indep MEC >
Structure.
3. Confirm to exit Integrated mode when prompted.
4. Confirm to save the model with a new name when prompted.
5. Enter [t_bracket_2 ] as a new name. Click Accept.
6. To get a better view of your part, click View in the upper right
hand corner, followed by Iso > Done. The model should like the
following figure.
Figure 14 Visualize the T_bracket in the Independent mode.
Task 4. Task 4. Generate the elements.
1. Create the elements by using AutoGEM. Click Model > Elements
> AutoGEM > Volume > All from the DESIGN menu. Click
<RETURN>.
2. A dialog box indicating the number of solid tetrahedral elements
that AutoGEM created will appear. Review the statistics and
record the number of elements and the time below.
� #Elements_________ Time_________ Click OK to finish.
3. To get a better view of the elements, turn off the visibility of all the
entities except the solid elements.
� Click Display > Master Visibilities from the DISPLAY menu.
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� Click All Off from the bottom of the form.
� Select Solids from the ELEMENTS column and click Accept.
4. Change the element display.
� Click Display > Settings from the DISPLAY menu.
� Select Smooth Shade from the DISPLAY TYPE drop-down
list.
� Select Fine from DISPLAY QUALITY drop-down list.
� Select Elements from the SHADE drop-down list.
� Select Shrink All Elements. Set the shrink factor to 0.2 .
5. Accept the settings. Your mesh should resemble the following
figure.
Figure 15 The bracket part meshed with Tetra solid elements.
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NOTES
Task 5. Task 5. Create brick idealizations. Delete the existing Tetra
mesh and all extra points.
Note:
For cases where solution time is critical, it is sometimes
quicker to create idealizations by hand. You hand mesh with
fewer elements than AutoGEM produces, and thus, reduceyour solution time drastically.
1. Re-display all the entities. Click Display > Master Visibilities >
All On > Accept.
2. Delete all the elements you just created. Click Edit > Delete >
Entity.
3. Click Solids > All, followed by <Return>.
4. Click Points > All, followed by <Return>. Click OK when
prompted.
5. Click Main > Geometry > Point > Single Points > Near.
Note:
The Near option places a point on a specified entity near a
projection point.
6. Click the bottom curve of the t_bracket. Then click the point
directly above it, as shown in the following figure.
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Pick this reference
point after selecting
the curve
Pick this curve first
Figure 16 Create a point for hand mesh.
7. Repeat this process to create three more points - your model should
look like the one shown in the following figure.
Figure 17 Create 3 more points.
8. Manually create elements. Click Main > Model > Elements >
Solid > Brick > Curve.
9. Select the curves shown in the following figure to create the first
face of the solid brick element.
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NOTES
Pick these two
curves
First face defined
from curves.
Figure 18 Create the first face of the solid brick element.
10. Select the opposing curves. A solid brick element appears.
11. Create the element in the middle.
� Select Point from the menu.
� Select the 8 points consecutively to form the element in the
middle.
12. Create the rest of the solids using either the Point or Curve option.
When you are completed your model should look like the
following figure.
13. Quit the application when finished. Click File > Quit > Yes > No.
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Figure 19 The finished hand mesh.
In the hand-created mesh, you have only four elements as compared to
sixty created by AutoGEM. Which one do you think will solve faster?
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EXERCISE 4: Using Rigid Connections
Figure 20 A symmetric plastic container is cut in half.
Task 1. Retrieve the container assembly and create a rigid connection.
1. Start Pro/ENGINEER. Set your working directory to the folder
that corresponds to the name of the current module.
2. Retrieve the RIGID_CONNECTION.ASM located in the current
working directory. The model is symmetric. All external load
and constraints are also symmetric about the same center plane.
3. Click Application > Mechanica. Click Continue in the UNIT
INFO dialog box.
4. Click Structure from the MECHANICA menu.
5. Click Idealizations from the STRC MODEL menu followed by
Rigid Connections > Create.
6. In the Rigid Connection dialog box, accept the default name.
7. Click the Select icon under SURFACE(S) and select the both
halves of the two holes surfaces as shown in the following
figure.
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Select these
surfaces
Figure 21 Select the indicated surfaces to create the rigid connection.
1. Click Done Sel > OK to finish.
2. Repeat the procedure on the other pair of tabs. The system displays
the rigid connection icons as shown in the following figure.
Figure 22 The rigid connection icon.
3. Click Done/Return to finish.
4. Save and erase the model.
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NOTES
EXERCISE 5: Using End and Perimeter Welds
Figure 23 The trailer frame assembly.
Task 1. Retrieve the frame assembly and create an assembly cut.
Because the model is symmetric, the analysis can be performed on one
quarter of the model.
1. Retrieve the FRAME.ASM located in the current working directory.
2. From the ASSEMBLY menu, click Insert > Cut > Extrude > Both
Sides > Done.
3. Specify ASM_TOP as the sketching plane by selecting Sel by
Menu. Pick ASM_TOP from the SELECTION TOOLS dialog box
and hit the Select button. Select Okay.
4. Click Right and select ASM_RIGHT as the reference plane by
selecting Sel by Menu. Pick ASM_RIGHT from the SELECTION
TOOLS dialog box and hit the Select button. Select Okay.
5. Specify the appropriate references and sketch the section, as shown
in the following figure.
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Sketch these 4
lines
Figure 24 Sketch the cut section.
6. Click [Done] to finish.
7. Click Flip > OK to remove the geometry outside of the rectangular
section.
8. Select Thru All > Done for depth option of both sides.
9. Click AutoAdd > OK so that the cut intersect all the components
based on the depth definition.
10. Click OK to finish cut definition.
Task 2. Compress the mid-surface of the assembly in the ASSEMBLY
mode.
1. Enter Pro/MECHANICA Structure. Click Mechanica from the
APPLICATION menu. Click Continue in the UNIT INFO window.
2. Click Structure > Model > Idealizations > Shells > Midsurfaces
> Compress > Shell only.
Select as four
references and …
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NOTES
3. The system highlights the MID_BAR.PRT and informs you that the
shell model is not defined in this component.
4. Click Yes > ShowCompress. The system displays the shell
models except the MID_BAR.PRT.
Note:
The shell models have been created in all components except
the MID_BAR.PRT. In the ASSEMBLY mode, you can
compress shell models that have been previously created in
PART mode. However you cannot create the shells in the
ASSEMBLY mode.
Task 3. Create the mid-surface of the shell model in part mode.
1. Retrieve the MID_BAR.PRT.
2. Enter Pro/MECHANICA Structure. Click Mechanica from the
APPLICATION menu. Click Continue in the UNIT INFO window.
Click Structure.
3. Click Model > Idealizations > Shells > Midsurfaces > Auto
Detect > Compress > Shell only > ShowCompress.
4. Click Done/Return > Done/Return > Done/Return.
Task 4. Compress the mid-surface of the assembly in the ASSEMBLY
mode again. Because all the shell models have been created in all the
components in the part mode, the system compresses and shows all
components.
1. Activated the frame assembly window. Click Window >
FRAME.ASM.
2. Click Structure > Model > Idealizations > Shells > Midsurfaces
> Compress > Shell only > ShowCompress.
3. Reorient to the TOP view and zoom in on the area indicated in the
following figure. Notice that there is a gap between the mid_bar
shell and the cross_bar shell.
4. Click Done > Done/Return.
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NOTES
Zoom in to
this area.
Figure 25 The gap between two shell models.
Task 5. Create end welds at one end of a sheetmetal part, as shown in
the following figure. Most end welds have been created for your
convenience.
1. Reorient to the DEFAULT view and zoom in on the area indicated
in the following figure.
Create end welds
at this end.
Figure 26 Create end welds at one end of a sheetmetal part.
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NOTES
2. From the IDEALIZATIONS menu, click Connections > End
Welds.
3. Specify the end weld surfaces:
� Select the hidden end surface of the sheetmetal MID_BAR.PRT,
as shown in the following figure by using Query Sel.
� Select the other surface, as shown in the following figure.
Select these two
surfaces
Figure 27 Select the end weld surfaces.
4. Create 3 more end welds on the end of the MID_BAR.PRT, using
the same procedures. The system displays the weld icons as shown
in the following figure.
5. Click Done/Return.
Figure 28 Create end welds on all 4 surfaces of the sheetmetal part.
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Task 6. Task 6. Compress the mid-surface of the assembly in the
ASSEMBLY mode again to verify the end weld connections.
1. From the IDEALIZATIONS menu, click Shells > Midsurfaces >
Compress > Shell only > ShowCompress.
2. Notice that the mid_bar shell and the cross_bar shell are now
connected. However, if you change your view to RIGHT there is a
gap between the bracket part and the cross bar, as shown in the
following figure.
Figure 29 The shell models of the bracket and the cross bar is not connected.
3. Click Done > Done/Return.
Task 7. Task 7. Create a perimeter weld.
1. From the IDEALIZATIONS menu, click Connections > Perim
Welds.
2. Specify the perimeter weld property. Click Current Props >
Thickness. Accept the default.
3. Click New and specify the end weld surfaces:
� Select the hidden end surface of the bracket part as the doubler
surface, as shown in the following figure using Query Sel.
� Select the edges of doubler to define weld location, as shown in
the following figure. Click Done / Sel.
� Select the base surface, as shown in the following figure.
Gap
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NOTES
Select the hidden bracket
surface as the doubler
surface
Select these edges.
Select this surface as the
base surface
Figure 30 Create the perimeter welds.
4. Click Done/Return.
5. Compress the model again to verify the connections. Click Done /
Return > Done / Return.
6. Save and erase the model.
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MODULE SUMMARY
In this module you learned:
• How to simplify a design using with idealizations.
• How to simplify a design using shell models.
• How to AUTOGEM elements in Independent mode.
• How to define rigid connections.
• How to define end and perimeter welds.
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Page 3-1
Module
Optimizing Models for AnalysisIn this module, you learn how different geometry creation
techniques used in Pro/Engineer integrate with Pro/MECHANICA.
You also learn Pro/Engineer techniques that reduce calculation time
in Pro/MECHANICA while maintaining accurate results.
Objectives
After completing this module, you will be able to:
• Create Pro/ENGINEER models for analysis.
• Use shell elements, solid elements, and regions.
• Model structural assemblies.
• Create 2-Dimensional models.
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INTEGRATED MODE MODELING
The first step in the Pro/MECHANICA analysis process is part creation.
You need to build a part before Pro/MECHANICA can analyze and
optimize it. The feature creation techniques you use when you build your
part will have a significant positive or negative influence on your modeling
experience. The integrated mode of Pro/MECHANICA unites geometry
creation with analysis. Consequently, you need to take into consideration
downstream activities such as analysis, sensitivity, or optimization as you
build your part. You need to think modeling, not just geometry, and you
need to plan ahead to increase efficiency.
To promote a flexible approach to part modeling, Pro/MECHANICA
enables you to define your model as either a solid or shell. The way you
define your model determines the type of elements Pro/MECHANICA uses
to model your part.
Solid Modeling
A solid model is a part that you model using solid elements like tetrahedrals,
bricks, or wedges. In Integrated Mode, Pro/MECHANICA uses only
tetrahedrals for solid modeling. As a rule, you use solid modeling when your
part is as thick and wide as it is long. Your part’s thickness, however, can
vary non-uniformly.
In Integrated Mode, element creation is automatic and transparent, with
analysis beginning immediately after the mesh is created. Although rare,
there are times when you may want to investigate the mesh.
Modeling Shells
A shell model is a part that you model using shell elements like triangles
and quadrilaterals. Typically, you use shell modeling when your part is
relatively thin compared to its length and width. To meet
Pro/MECHANICA’s criteria for shell models, your part must have either a
constant or a “semi-constant” thickness
Defining Midsurfaces
Pro/MECHANICA does not support shell elements that vary non-uniformly
in thickness (tapered), but your part can have multiple constant uniform
thickness areas.
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Using shell elements can result in models with fewer elements that will run
faster and require less disk space than a solid model.
For Pro/MECHANICA to treat your part as a shell model, you typically
need to complete a three-step procedure. The purpose of this procedure is to
direct Pro/MECHANICA to treat the part as a shell model and to specify
how shell elements are constructed. The following is a summary of the
procedure:
• Defining shell pairs – The first step is to define ‘pairs’ of solidsurfaces which will be ‘compressed’ to form the ‘mid-surface’ of the
model. A surface/shell ‘pair’ consists of two or more parallel surfaces on
opposite sides of a volume.
• Test the pairs compression – Once the pairs have been defined,MECHANICA attempts to compress all the pairs to a continuous surface
model representing the ‘middle’ of the part. You can and should review
this mid-surface model to ensure that it has compressed to the desired
form, i.e. you should ‘test the compression’.
• Verify the Use Pairs setting – To ensure that Pro/MECHANICA treatsthe model as a shell, you should verify that the Use Pairs setting is
clicked. Pro/MECHANICA uses this setting to determine whether to
perform solid or shell modeling.
Figure 1 A shell model.
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Automatically Create the Midsurfaces
If you use feature creation methods that implicitly contain a “thickness”
dimension, you can pair these surfaces automatically using the Auto Detect
option. Feature creation methods that implicitly contain thickness type
dimensions are:
• Shells • Ribs
• Ears • Thin Protrusions
• Sheet Metal
Suppressing Cosmetic Features
Pro/ENGINEER allows you to create parts with great detail and precision.
However, there are many features in a model that are irrelevant in analysis
computations. For instance, a part may include a company logo etched on
the surface; although this detail is important for cosmetic purposes and
drawings, it has virtually no effect on stress in the model. Sending features
like this to Pro/MECHANICA serves only to increase solution time and disk
space requirements because AutoGEM has to generate many extra elements
to capture these structurally insignificant features. These features should be
suppressed before you run an analysis.
Preparing Your Part for Static Analysis
To help reduce the number of elements that AutoGEM makes, you can
de-feature a model. Features that you might typically suppress are:
• Small Cuts and Grooves • Rounds and Chamfers
• Locating Holes and Small Counterbores • Ejection Bosses
• Logos
Whether the features in a part are purely cosmetic or structurally significant;
AutoGEM gives them equal importance and will create elements to capture
every small detail. Normally, these types of features can be removed from
the part before the start of a run. This can result in a drastic improvement in
analysis performance, such as faster run times and smaller disk space
requirements without affecting the solution’s accuracy. Usually it is obvious
which features are important to the analysis and which are purely cosmetic.
However, it is up to the user to determine which features are truly
significant to the analysis.
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NOTES
Geometric Symmetry
Another way to drastically reduce run time and disk requirements is to take
advantage of symmetry. It is important to note that your model must not
only have symmetrical geometry, but the loads and constraints must be
symmetric about the cutting plane as well. When this is the case, it is a good
idea to prepare your geometry before you begin the analysis process. In
Pro/ENGINEER, you simply cut away the symmetric portions of the model.
Many models can be cut into halves, quarters, or even smaller sections if the
part’s geometry, constraints, properties and loads are all symmetric about a
cutting plane.
Another time saving type of symmetry supported by Pro/MECHANICA is
Cyclic Symmetry. Cyclic symmetry is fairly specialized and is often used
for analysis of rotating machinery such as turbine blades, pump impellers
etc.
Creating Regions
Regions are used to apply loads and constraints to particular “footprints” on
a model. Surface Regions may be created in Pro/MECHANICA to apply
loads and constraints to specific localized surface areas. Surface region
creation is a two step process.
• Defining the region boundary is accomplished either by creating adatum curve to represent the boundary or by sketching the boundary on
the fly. A separate datum curve feature must be created for each region
that you wish to define. You cannot define multiple boundaries with one
datum curve feature.
• Creating the region consists of splitting the model surface into regionsusing the boundary
As of Release 2000i, features such as Datum Points, Curves and Coordinate
Systems can be created either in Pro/MECHANICA or in Pro/ENGINEER.
You must create your regions before defining Mid Surfaces for Shell
Modeling, because assigning regions can invalidate existing shell pairs.
While Surface Regions may be created in Pro/MECHANICA to apply loads
and constraints to specific localized surface areas, similar functionality
allows solids to be split into three-dimensional regions. This is done by
creating Volume regions. Creation of the Volume Region simulation feature
is similar to that of the Cut feature in Pro/ENGINEER. It can be created in
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NOTES
part or assembly models and inherits the material properties from the solid
geometry within which they are created. Since results may be viewed by
volume, these regions are beneficial in preparing a model for
postprocessing, making it easier to view internal stresses, strains, etc. Since
elements must be created within a volume region, they can also be used as
an effective means of increasing mesh density when required.
Structural Assemblies
While understanding how parts behave individually is important, many
times these parts are bolted or welded to other parts in an assembly. Their
interaction may require analyzing the parts joined together in a structural
assembly. You must understand how to prepare an assembly for a shell
model and for a solid model, as well as how to take advantage of the
differences between shell and solid models.
Layers and Groups
Layer functionality is fundamental to organization and working efficiently
in Pro/Engineer. When a model is transferred to independent
Pro/MECHANICA you have the option of transferring Pro/E layers to
Pro/MECHANICA groups. The advantages of groups in independent mode
are numerous. Groups allow ease of use when clicking or manipulating
entities—especially elements. This is very useful in both model preparation,
as well as in post-processing. For example, if you want to view the stress
fringe results for only one part in an assembly (as opposed to viewing the
results on the entire assembly), you can view results by group.
Mixed Meshing
In some cases, you combine different element types. This is done simply by
providing Pro/MECHANICA with the geometry associated with the desired
element type and by verifying settings. When MECHANICA, Settings,
Use Pairs is checked on, any existing shell pairs will be meshed with shell
elements, while any remaining unpaired part geometry will be meshed with
solid elements.
This functionality works as well on single parts that are partially paired.
Mixing element types is sometimes critical in balancing time savings with
required accuracy.
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NOTES
Interfacing Solids and Shells
How does Pro/MECHANICA handle the intersection of the shell and solid
elements? When the analysis is run in Integrated mode, AutoGEM will
automatically place Links on the edges where shell and solid elements
intersect. Links ensure identical displacements at these locations. If you
were to view a mixed-meshed model in Independent mode, the interface
between the shells and solids would appear as shown in the following figure.
Figure 2 A mixed-meshed model.
The solids are the dark gray, the shell element on the gusset is light gray,
and the links are shown as dotted lines at the intersection of the shells and
solids. They can be created automatically or manually in Independent
modes.
The links are very convenient and are used commonly, but do cause an
increase in run time and can affect accuracy. Therefore, there is an
alternative to links when combining solids and shells, or beams and shells
for that matter. The alternative is to create transition elements between the
shells and solids. This is known as masking. Usually the mask elements are
made of the same material as the solids they interface with. They need to be
very thin so they do not add significant stiffness to the model.
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Modeling in 2-D
It is possible to define 2-D model types in Pro/MECHANICA Integrated
mode. For Structure, the available model types are Plane Strain, Plane
Stress, and 2-D Axisymmetric. For the Thermal module the available model
types are 2-D Plate, 2-D Unit Depth, and 2-D Axisymmetric. The default
model type is 3D.
The suggested procedure to define a model to be used in a 2-D analysis
using Integrated mode is as follows:
• Define a reference coordinate system - To prepare the model for a 2-D analysis, a reference coordinate system must be created before the
model type is changed. The coordinate system can be created in
Pro/ENGINEER or in Pro/MECHANICA.
• Select the model type - The model type should be selected before anyloads, constraints, or material properties are defined on the model.
Changing the model type from 3-D to 2-D causes all modeling entities to
be deleted. The available model types are:
� 3-D - Use this option if any aspect of the model goes out of the
WCS XY plane. Most of your models will be 3D. This is the
default model type.
� Plane Stress (Structure) or 2-D Plate (Thermal) - Model
should be thin and all modeling entities (properties, constraints,
loads, and geometry) must lie in the XY plane of the reference
coordinate system.
� Plane Strain (Structure) or 2-D Unit Depth (Thermal) -
Model should be sufficiently long such that strains in the
transverse z direction are negligible. All modeling entities must
lie in the XY plane of the reference coordinate system.
� 2-D Axisymmetric - Geometry and all modeling entities should
be symmetric about an axis. All modeling entities must lie in the
positive x portion of the XY plane of the reference coordinate
system.
• Select the geometry and reference coordinate system - Once amodel type is selected, the user is required to select the geometry and
reference coordinate system for the model. If either selection is invalid,
the model type will not be changed.
• Define loads and constraints - Once the model type has beenselected, the loads and constraints can be defined. The model should
only be loaded in the XY plane.
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NOTES
• Define shell properties - For a Plane Stress or 2-D Plate model, shellproperties must be defined to assign a thickness to the model. This step
is not necessary for other 2-D model types unless shell elements will be
used. If shell properties are not assigned to the plane stress surface, an
error will be found during error checking.
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NOTES
LABORATORY PRACTICAL
Goal
To learn effective techniques for preparing thick and thin parts for
analysis.
Method
In Exercise 1, you suppress the purely cosmetic features on your part in
preparation for analysis.
In Exercise 2, You create a shell model from a T-bracket and create the
midsurfaces both manually and automatically.
In Exercise 3, you use Auto Detect to shell model the handle part.
In Exercise 4, you create simple sketched and projected regions in order to
understand regions and their affects on pairing.
In Exercise 5, you prepare an assembly for a shell model and for a solid
model.
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NOTES
EXERCISE 1: Suppressing Structurally InsignificantFeatures
Figure 3 A realistic handle.
Task 1. Open the part handle.
1. Set your working directory to the folder that corresponds to the name
of the current module.
2. Open the HANDLE.PRT. The model should appear as shown in the
figure above.
Task 2. Create and review the elements in the Independent Mode. Send
the fully featured model to Independent Pro/MECHANICA and use
AutoGEM to find out how many elements are needed to mesh the part. This
will give you an indication of how model complexity can affect the number
of elements, and consequently solution time, and disk space requirements
for a fully detailed part.
1. Click Applications > Mechanica. Click Continue in the UNIT
INFO window
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NOTES
2. Before enter the Independent mode, verify that the Use Pairs setting
is turned off. Recall that this is found under Settings.
3. Enter the Independent mode. Click Independ MEC > Structure.
Confirm when prompted.
4. Save the model with a new name when prompted. Enter [handle_2 ]
as a new name. Click Accept.
5. Click View > Iso >Done. The model should appear as shown in the
following figure.
6. Note that all the features were transferred, and that you have a clean
single volume part ready for AutoGEM. To confirm that you have a
single volume, click Review > Model Summary from the tool bar
and verify that there is only one volume. Click OK when finish.
Figure 4 Handle part in the Independent mode.
Task 3. Mesh the part using AutoGEM.
1. Generate the elements, click Model > Elements > AutoGEM >
Volume > All. Then press <RETURN>.
2. Record the number of elements and how long it took from the
AUTOGEM SUMMARY dialog box,.
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NOTES
� The number of elements_______________
� Time _______________
� Element type ______________
� Reason for generating this type of element ____________
� Click OK to finish.
3. To get a better view of the elements, turn off the visibility of all the
entities except the solid elements. Click Display > Master
Visibilities from the DISPLAY pull-down menu.
4. Click All Off from the bottom of the form.
5. Select Solids from elements. Click Accept.
6. Shade the elements.
� Click Display > Settings from the DISPLAY pull-down menu.
� Select Smooth Shade for the DISPLAY TYPE.
� Select Fine for the Display Quality.
� Select Elements for the SHADE.
� Select Shrink All Elements check box. Set the Shrink Factor to
0.2 .
7. Accept the settings.
8. Click File > Quit from the top tool bar. Do not save the model.
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NOTES
Chamfers
Locator Holes
Name Plate
recess
Figure 5 Suppress these features.
Task 4. Suppress the structurally insignificant features.
1. Start Pro/ENGINEER and set the working directory to the folder that
corresponds to the name of the current module.
2. Retrieve the handle part.
3. Suppress the locator pin holes, the chamfers, and the recess. Click
Feature > Suppress > Clip, select the chamfer from the MODEL
TREE, followed by Done. The system suppresses all the subsequent
features.
Task 5. Transfer to Independent Mode and AutoGEM.
1. Repeat earlier steps to transfer the part to Independent
Pro/MECHANICA and AutoGEM it. Rename it in MECHANICA to
any name you want. Record the number of elements and time to
mesh.
Number of Elements ________ Time to mesh ___________.
2. Compare this mesh to the previous result.
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Opt imiz ing Models fo r Analys is Page 3-15
NOTES
3. Click File > Quit. Do not save the model.
Note:
When performing a thermal or modal analysis, the round and the
holes may become insignificant and can be suppressed as well,
further reducing the element count.
Task 6. Reduce the element count by removing symmetric geometry. This
technique is only valid under symmetric situations, which will be discussed
in detail in later chapters.
1. Start Pro/ENGINEER and set the working directory to the folder that
corresponds to the name of the current module.
2. Retrieve the handle part. Notice that the features remain suppressed.
3. Restore all the suppressed features. Click Feature > Resume > All >
Done.
4. Close examination of the part shows that it is symmetric about
DTM3. When the load and constraints are also symmetric about
DTM3, the model can be cut in half.
5. Cut the part in half at DTM3. Click Insert > Cut > Extrude > One
Side > Done.
6. Sketch on the bottom horizontal surface of the handle, with DTM3 as
the TOP horizontal reference plane.
7. Sketch a rectangle to encompass the redundant geometry, as shown
in the following figure.
8. Click [Done] to exit the sketching environment.
9. Click Flip if necessary, so that the arrow points to the inside.
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NOTES
Figure 6 Sketch the rectangle to cut away the geometry.
10. Select Thru All for the Depth, then click Done> OK. The model
should appear as shown in the following figure.
Figure 7 Half of the handle.
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NOTES
Note:
When you AutoGEM this fully featured half model, you would
get about half the number of elements. Using these simple, but
powerful, techniques will drastically reduce analysis time.
Task 7. (Optional) Automesh in the Independent Mode and compare the
element count.
1. Repeat earlier steps to transfer the part to Independent
Pro/MECHANICA and AutoGEM it. Record the number of elements
and the time below.
2. Number of Elements ________ Time to mesh _________.
3. Click File > Quit from the top tool bar. Do not save the model.
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NOTES
EXERCISE 2: Shell Modeling by DefiningMidsurfaces
Task 1. Retrieve the T-Bracket. Manually create the first set of pairs.
Define the pairs for the base of the bracket.
1. Start Pro/ENGINEER and set the working directory to the folder that
corresponds to the name of the current module.
2. Retrieve the T_BRACKET.PRT.
3. Enter MECHANICA. Click Applications > Mechanica. Click
Continue > Structure.
4. To prepare the model for shell creation. Click Model >
Idealizations > Shells.
5. Click Midsurfaces > New, accept the default Constant. Select the
two surfaces, shown in the following figure to define the first and
second set of pairs. Use Query Sel as necessary.
Pair #1
Pair #2
Figure 8 Create two surface pairs.
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NOTES
Task 2. Test the midsurface compression to verify that you have defined
the pairs correctly.
1. Click Compress from the MIDSURFACES menu, then click Shells
only.
2. To display the midsurface geometry, click ShowCompress. The
pairs get compressed to their midsurfaces and displayed in yellow.
Figure 9 The midsurface.
3. To display the original geometry, click ShowOriginal.
4. Click Show Both to display both the original geometry and the
compressed midsurface simultaneously.
5. Click Done/Return twice when finished. The meshed model can be
visualized in the Independent Mode, as shown in the following
figure.
Figure 10 Midsurface in the Independent Mode.
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NOTES
Task 3. Use the Auto Detect option to generate midsurfaces in the T –
Bracket.
1. Delete all existing pairs. Click Model > Idealizations > Shells >
Midsurfaces > Delete > Select All > Yes.
2. To automatically create the pairs, click Auto Detect from the
MIDSURFACES menu.
3. Pro/MECHANICA highlights the pairs that it was able to
automatically create. One surface in each pair is red and the other is
yellow.
4. Test the compression. Click Compress > Shells only >
ShowCompress from the MIDSURFACES menu.
5. The midsurface displays in yellow.
Figure 11 Midsurface compressed from Auto Detect.
6. Display the original geometry as necessary.
7. Click Done > Done/Return> Done/Return.
8. Save and erase the file. Click File > Save. Click Applications >
Standard > File > Erase > Current > Yes.
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NOTES
EXERCISE 3: Shell Modeling Using Auto Detect
Task 1. Retrieve the handle part and attempt to Auto Detect and compress
the surface pairs.
1. Open the HANDLE.PRT. Resume all the suppressed features.
2. Click Applications > Mechanica > Structure > Model >
Idealizations > Shells > Midsurfaces.
3. Click Auto Detect > Compress > Shell Only. The system informs
the unpaired geometry.
4. Click Done/Return twice.
Task 2. Suppress the counterbores.
1. Click Applications > Standard. Display the MODEL TREE if
necessary.
2. Suppress the unpaired geometry. Click Feature > Suppress > Clip,
select the HOLE ID 221 from the MODEL TREE, followed by Done.
The system suppresses all the subsequent features. The handle
should appear as shown in the following figure.
Figure 12 The handle without unpaired surfaces.
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NOTES
3. Enter MECHANICA and Auto Detect the midsurfaces. Note that not
all the surfaces paired. The unpaired geometry are the two separately
created rounds.
4. Manually pair the inner and outer rounds. Click New from the
MIDSURFACES menu. Accept the default Constant, then select the
inner and outer round surfaces.
5. Compress again. The model should appear as shown in the following
figure.
Figure 13 The compressed handle.
6. Click Done/Return twice.
7. Switch to the standard application. Save and erase the model.
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Opt imiz ing Models fo r Analys is Page 3-23
NOTES
EXERCISE 4: Creating Regions
In order to constrain or load a specific portion of a part’s surface, you need
to create a region on the surface. You will use the simple 254 x 254 x 25.4
steel plate and create circular regions on each side of the plate where you
want to apply loads.
Figure 14 Create regions for applying the load.
Task 1. Create the first datum curve.
1. Open the REGIONS.PRT.
2. Enter Pro/MECHANICA Structure. Click Application > Mechanica
> Continue > Structure.
3. Create the datum curve on the top of the plate. Click Model >
Features > Datum Curve > Create > Sketch > Done.
4. Select the top surface of the plate as the sketching plane.
5. Flip the arrow so it points out of the plate, followed by Okay.
6. Click Bottom, and pick the bottom side of the plate as the horizontal
reference.
7. Select the top side and the left side for sketching references and
sketch the section as shown in the following figure.
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NOTES
Figure 15 The sketched section.
8. Finish the curve and switch to the default view. Click [Done],followed by OK.
Task 2. Create the second datum curve.
1. Create a second datum curve on the bottom of the plate. From the
SIM FEAT OPER menu, click Create > Sketch > Done.
2. Select the bottom surface of the plate as the sketching plane.
3. Specify the appropriate sketching references and sketch the section
as shown in the following figure.
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Opt imiz ing Models fo r Analys is Page 3-25
NOTES
Figure 16 Sketch another curve on the other side.
4. Click OK to complete the curve.
Task 3. Use the datum curves you to define the regions.
1. Create a surface region. From the SIMULAT FEATS menu, click Surf
Region > Create > Select > Done.
2. Select the top datum curve.
3. Select the top surface as the surface to split, followed by Done Sel >
Done > OK.
4. Follow the same procedure to create the bottom region.
5. Verify the defined regions. From the VIEW drop-down list, click
Model Setup > Mesh Surface. Select the top and bottom circular
regions. The model should appear as shown in the following figure.
Note:
Mesh surface in the previous step is a Pro/ENGINEER
functionality for visualizing surfaces. It has nothing to do withelement generation.
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NOTES
Figure 17 Visualize the surface regions.
6. Close the MESH dialog box and repaint the screen.
Task 4. Manually define the midsurface.
1. Click Done/Return. From the STRC MODEL menu, click
Idealizations > Shells > Midsurfaces > new.
2. Ensure that the model is shaded. Select the top surface of the model
using Query Sel (outside the circular region).
3. Select the bottom surface of the model (outside the circular region).
4. Click Done Sel when finished.
5. Test the compression. Click Compress > Shells only. Notice the
error message in the message box regarding unpaired surfaces, and
also that the COMPRES MDL menu looks different than it usually
does.
Note:
When you created the regions, you actually split the surfaces.
The top and bottom faces now each consist of two surfaces. You
need to include all four surfaces in the pair definition.
6. From the Midsurfaces menu click Edit > Edit Pair. Pick either the
top or bottom surface. Shade the model as necessary.
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Opt imiz ing Models fo r Analys is Page 3-27
NOTES
7. Click Add Surface. The unpaired surfaces are not displayed in red
and yellow.
8. Select the top circular region and the bottom circular region. Notice
the color change.
9. Click Done/Return from the EDIT PAIR menu.
10. Test the compression. Click Midsurface > Compress > Shells only
> Show Compress. The entire model should appear as shown in the
following figure.
Figure 18 The compressed shell midsurface.
Task 5. Automatically define the Midsurface. The plate was created as a
thin feature, you can automatically create the pairs.
1. Delete the existing shell. From the MIDSURFACES menu, click
Delete > Select All to delete the surface pairs that you have already
manually defined.
2. Confirm when prompt.
3. From the MIDSURFACES menu, select Auto Detect to automatically
pair the part.
4. Test the compression. Notice how Auto Pair automatically included
the regions you defined.
5. Return to the top-level menu. Switch to Pro/ENGINEER.
6. Save and erase the model.
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NOTES
Note:
You will see how Pro/MECHANICA interprets loads and
constraints that are applied to overlapping regions in later
sections. But for the time being, you just need to know how to
define them.
EXERCISE 5: Creating Volume Regions
Volume regions can be created in part or assembly models. They inherit the
material properties from the solid geometry within which they are created.
Since results may be viewed by volume, these regions are beneficial in
preparing a model for post-processing, making it easier to view internal
stresses. strain, etc.
Task 1. Open the part VOLUME_REGION.PRT.
1. Open VOLUME_REGION.PRT.
2. Enter Pro/MECHANICA Structure. Click Applications >
Mechanica > Continue > Structure.
Task 2. Create a volume region.
1. Click Model > Features > Volume Region > Create > Extrude >
Done.
2. Select either end face of the shaft as a sketching plane.
3. Click OK to accept the direction of feature direction into the
cylinder, followed by Default.
4. In Sketcher, click [Use edge]. Click both semi-circular edges to
form a circular sketch.
5. Click [Done].
6. Click Done to accept the default depth option Blind. Enter [10].
7. Click OK to finish the definition. Switch to hidden line if necessary,
to see the created region.
8. Verify the defined region.
� Click View > Model Setup > Mesh Surface.
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NOTES
� Select the surfaces of the created region. The system meshes the
selected surfaces.
� Click Close when finished.
9. Save and erase the model.
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NOTES
Exercise 6: Structural Assemblies
Figure 19 the Gusset Assembly
Task 1. Idealize the GUSSET.PRT as a shell.
1. Open the GUSSET.PRT.
2. Enter Pro/MECHANICA Structure. Click Applications >
Mechanica > Continue > Structure.
3. Select surface pair to create the midsurface.
� Click Model > Idealizations > Shells > Midsurfaces > New >
Constant.
� Select the paired surfaces. Spin the model as necessary.
4. Click Done/Return > Done/Return > Done/Return.
5. Switch to the standard application.
6. Save the model.
Task 2. Retrieve the gusset assembly.
1. Retrieve the gusset assembly. This model is created using assembly
constraints, such as MATE and ALIGN. The GUSSET.PRT has been
idealized as shell. The plate is not idealized as shell, hence a solid.
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NOTES
2. Verify that the assembly units have been set to mm N s as necessary.
Click SetUp > Units, select mm N s, click Set.
Task 3. Mix idealize the model.
1. Enter Pro/MECHANICA Structure. Click Applications >
Mechanica > Continue > Structure.
2. Click Model > Idealizations > Shells > Midsurfaces > Compress
> Shells and Solid > Show Compress. The model should appear
as shown in the following figure.
Figure 20 An assembly with mixed idealizations.
3. The interface between the shell GUSSET.PRT and the plate parts are
handled by the system. Had you created and run an analysis in the
Independent mode, then the system will create links between the
solid and shell idealization.
4. Switch to Pro/ENGINEER and erase the model.
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Page 3-32 Fundamenta ls o f Pro /MECHANICA
NOTES
EXERCISE 7: Modeling a 2-D Plane Stress Plate
Task 1. Define the PLATE_2D.PRT as a plane stress model.
1. Open the PLATE_2D.PRT.
2. Switch to the default view. Notice that the back surface of the model
lies in the X-Y plane.
3. Enter Pro/MECHANICA Structure. Click Applications >
Mechanica > Continue > Structure.
4. Specify the model type. Click Model > Model Type.
5. In the MODEL TYPE dialog box, click Plane Stress. The Select
Geometry and Select Coordinate System option becomes
available.
6. Try to define the Plane Stress model using the front surface.
� Click Select Geometry. Select the front surface of the model,
followed by Done Sel.
� Click the Select Coordinate System. Select the only available
coordinate system, followed by Done Sel.
� Click OK to finish. The system informs that the surface does not
lie in the X-Y plane. Close the information window.
7. Define the Plane Stress model using the back surface.
� Click Select Geometry> Unsel Last. Select the front surface of
the model to remove.
� Select the back surface of the model, followed by Done Sel.
� Click the Select Coordinate System and select the only
available coordinate system.
� Click OK > Confirm to finish. The model is defined as a plane
stress model successfully.
Task 2. Define shell properties to assign material and thickness to the
model.
1. Click Idealization > Shells > New. The SHELL DEFINITION dialog
box appears.
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Opt imiz ing Models fo r Analys is Page 3-33
NOTES
2. Define the shell:
� Accept the default name.
� Click [Select]. Select the same surface that is used to define
the plane stress model by using Query Sel, followed by Done
Sel.
� Accept the default type Simple.
� Enter a thickness of [3].
� Assign the material properties to the model. Click More next to
the MATERIAL drop down list. Click AL6061 from the list. Add
it to the model. Click OK to finish material definition.
� Click OK to finish shell definition.
3. Click Done/Return twice to return to the top-level menu.
4. Switch to the standard application.
5. Save and erase the model.
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NOTES
MODULE SUMMARY
You have learned:
• How to simplify a model for analysis by suppressing features and usingsymmetry.
• How to shell models using a midsurface.
• How to create regions for loads and constraints.
• How to prepare an assembly for a shell model and for a solid model.
• How to define a model to be used in a 2-D analysis using Integratedmode.
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Page 4-1
Module
Assigning Material PropertiesIn this module, you learn how to assign material properties to a part
and how to define a library of material properties.
Objectives
After completing this module, you will be able to:
• Assign structural and thermal properties to parts.
• Define linear and nonlinear properties.
• Create materials libraries.
• Define temperature-dependent material properties.
• Edit and delete material properties.
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NOTES
BASIC MECHANICS OF MATERIALS
You must have a thorough understanding of relevant engineering units
when running analyses Pro/MECHANICA.
• What is the value of density? What are its units?
• What is the value of Young's Modulus? What are its units?
• What is Poisson's Ratio, and what are its units?
• What are the units of Coefficient of Thermal Expansion?
.
Yield Stress
Young’s Modulus is the Slope offthe linear portion of Stress/StrainCurve.
Ultimate Stress
Strain ε
Stress σ
Figure 1: Strain-Stress Curve
Young's Modulus
The previous graph shows a sketch of a general stress-strain curve. These
curves are created by applying an increasing axial load to a test specimen
and by measuring the load and deformation simultaneously. From this
data, the stress (the vertical axis) can be plotted against the strain or
percent elongation (the horizontal axis). As the axial load is increased, the
strain increases in a linear fashion. The slope of this line is called Young's
Modulus. The units are stress (load/area) over strain (change in
length/original length).
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Ass igning Mater ia l Propert ies Page 4-3
NOTES
Poisson's Ratio
Poisson's Ratio is the ratio of lateral strain to longitudinal strain. Its value
is between 0.25 and 0.33 for most metals. For example, if you had a round
bar of steel that was 250 mm long and 25 mm diameter, with a Poisson's
Ratio of 0.3, and if you pulled on it so that it deformed 25 mm axially
from 250 mm to 275 mm, the resulting change in diameter would be:
υ = Poisson’s Ratio = axial
lat
εε
where 1.0250
25 ==axialε
so 03.01.03.0 =⋅==υεε lat where d
dlat
∆=ε , d and ∆d are initial diameter
and the change of diameter respectively. then
mmdd lat 75.02503.0 =⋅==∆ ε . The new diameter would be:
mmdddnew 25.2475.025 =−=∆−=
Most materials (when unrestrained) expand when heated and contract
when cooled. The strain due to a 1 degree temperature change is known as
the coefficient of thermal expansion, which is the change in length over
original length over temperature. The units are strain units over
temperature:Fin
in
°,
Cm
m
°
Failure begins whenever the part's actual stress exceeds its Yield Strength.
Pro/MECHANICA always assumes that the Young's modulus has a
constant slope. Analyses that only consider the straight-line portion of the
stress-strain curve (constant Young's Modulus) are considered linear. If
the maximum stress in your model exceeds the material's Yield Stress,
then the reported values are not accurate.
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NOTES
.
Yield Stress
Ultimate Stress
Young’s Modulus is the Slope of thelinear portion of Stress/Strain Curve.
Pro Mechanica is a linear Code.
Stress σ
Strain ε
Figure 2 Linear elastic model.
Systems of Units
When changing the units system for a model, you have the option to
convert existing numbers or interpret existing numbers.
If you build a part in IPS (Inch-Pound-Second; Pound in this system
assumes “Pound Weight”) that is 10 inches long, and then switch to
mmNS using the “Convert Existing Numbers” option (same size), then
Pro/ENGINEER would re-dimension your model to be 254mm long.
If you choose the “Interpret Existing Numbers” option (same dimensions),
then your part would become 10mm long.
IPS and I-lbm-S (Inch-Pound Mass-Second) are different unit systems.
The unit for mass in IPS is lbf-sec^2/in, whereas the unit for mass in I-
lbm-S is lbm. These two systems differ as to whether your model is mass
driven or force driven. If your model is force driven, then your units of
mass are considered to be in Weight density which differs from Mass
density by the gravitational constant, gc= 386.4.
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Ass igning Mater ia l Propert ies Page 4-5
NOTES
LABORATORY PRACTICAL
Goal
To create a library of material properties and assign the properties to a
model.
Method
In Exercise 1, you assign structural and thermal material properties to a
part.
In Exercise 2, you review some basic mechanics of materials.
In Exercise 3, you add your own material to the library.
In Exercise 4, you edit a material properties file and define temperature
dependent material properties.
EXERCISE 1: Assign Structural and ThermalMaterial Properties
Task 1. Define a system of units for your model in Pro/ENGINEER. By
default, Pro/ENGINEER assumes all models are in units of inches-pounds
mass-seconds-Fahrenheit.
1. Set your working directory to the folder that corresponds to the
name of the current module. Open the T_BRACKET.PRT.
2. Change this setting, click Setup > Units.
3. The dialog box displays the available systems of units. Change to
millimeter Newton Second (mmNs) as necessary.
4. Enter Pro/MECHANICA, click Applications > Mechanica. (Note
the units.)
5. Assign the material properties of steel to this part. Click Structure
> Model > Materials.
6. The material window appears. Add STEEL to the MATERIAL IN
THE MODEL.
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NOTES
7. Click Assign> Part, select the part. Click Done Sel.
Task 2. Review the properties.
1. Select STEEL from the Material in model column and click Edit.
2. The MATERIAL DEFINITION dialog box for Steel appears and
gives you the opportunity to review the values for:
• Density • Cost Per Unit Mass
• Young's Modulus • Poisson's Ratio
• Coefficient of
Thermal Expansion
3. Select the Failure Criterion tab in the Material Properties dialog
box. Select the Distortion Energy (vonMises) option from the
drop-down list.
4. Enter [231] for the TENSILE YIELD STRESS.
5. Accept the default N / mm^2 unit from the drop-down list.
6. Click OK when finish.
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NOTES
EXERCISE 2: Adding New Materials to the Library
Task 1. Create a new material that is not in the Pro/MECHANICA
Material library. Assign this new material to the T-Bracket. Save this new
material to your own custom material library.
1. Click New, to open the MATERIAL DEFINITION dialog box.
2. Select the units you want and enter the properties listed below.
You could flip from unit to unit by selecting it, MECHANICA will
do the conversion accordingly.
Material Name NICKEL
Description Nickel Material Properties
Mass Density 8802 kg/m3 or 17.08 slug/ft
3
Young's Modulus 206843 N/ mm^2 or 30E06 psi
Poisson's Ratio 0.31
Coeff of Thermal
Expansion
1.296E-05 /C or 7.2E-06 /F
3. Click OK.
4. Add the new material to the library. In the MATERIAL dialog box,
click on the arrow pointing toward MATERIAL IN LIBRARY. Click
Yes to add the property to library.
5. Assign the new material to the part
� Select the new material.
� Click Assign > Part.
� Click the part.
� Click DoneSel > Yes.
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EXERCISE 3: Edit and Delete Materials
Task 1. Edit all the AL6061 in the Material Library and make Poisson’s
Ratio temperature dependent.
1. Select AL6061 from the Library column and click on the arrow to
place it in the model column.
2. Select it and click Edit.
3. In the Material Properties data form for POISSON'S RATIO type,
click the function button, f(x).
4. In the function definition form, enter the name
[Poisson_Function ], and the description [Temperature
Dependent Poisson’s Ratio ].
5. Select Table from TYPE drop-down list. Select the temperature
drop-down list, and notice that temperature is the only option
available. Material properties can only be dependent upon
temperature.
6. Click Add Row. In the Enter Rows dialog box, click OK to accept
the default values.
7. Enter table values as shown below in the following figure.
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Figure 3 Enter the table values.
8. Click OK. Note the value of Poisson’s Ratio is now the
Poisson_Function you defined.
9. Click OK to accept.
10. Click on the left arrow to place it back in the library.
11. Click Yes > Yes to overwrite existing library.
12. Close the dialog box. Save the model.
13. Return to Pro/ENGINEER and erase the model.
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MODULE SUMMARY
You have learned:
• How to assign structural and thermal properties to a part.
• How to create a materials library.
• How to edit material property files.
• How to define temperature dependent material properties.
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Module
Applying ConstraintsIn this module, you learn how to apply different types of constraints
to your model.
Objectives
After completing this module, you will be able to:
• Create different types of constraints.
• Constrain models in Pro/MECHANICA.
• Set the active coordinate system.
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INTRODUCTION
Constraints and loads are Pro/MECHANICA features that simulate the real-
world environment that you expect your model to encounter.
Pro/MECHANICA uses this information to calculate the behavior of your
model during analyses and sensitivity studies. Your model's optimal shape
and mass will depend on the constraints and loads you define.
A Constraint is an external limit on the movement of a structure or portion
of a structure. A load is a force, pressure, acceleration, velocity or moment
you apply to a structure or portion of a structure. The way you constrain
your model differs depending on whether you are working in Structure or
Thermal.
For Pro/MECHANICA to perform most types of analyses, you must apply
at least one constraint to your model. When you apply constraints in
Integrated Mode, Pro/MECHANICA associates the constraints with the
part's geometry rather than the elements it will create during the analysis
phase.
Before you add constraints to your model, be sure you have all the
necessary geometry and references you need in place. Pay particular
attention to the following items:
• Coordinate Systems – If you plan to make a constraint relative toany coordinate system other than the World Coordinate System
(WCS), then that coordinate system needs to be in place and active.
You can specify constraints relative to a user-defined coordinate
system of the following types:
• Cartesian
� Cylindrical
� Spherical
� Datum Points – If you plan to constrain a specific point on an
exterior curve or surface, your part needs to include a datum
point at that location. As we will discuss later in this class, this
method is generally not recommended because it causes
singularities (infinite stress) to occur in your model. However,
under rare circumstances, you may choose to use this option.
• Regions – If you plan to constrain a specific surface region, yourmodel needs to include the datum curve contours defining that region.
In defining constraints for a Structure model, your goal is to fix portions of
the part's geometry so the part cannot move or can only move in a specific
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NOTES
way. Pro/MECHANICA assumes any unconstrained portion of your part
is free to move in all directions available for that model type.
Fixing your part in space provides Pro/MECHANICA with a basis for
understanding how to treat your part. For most Pro/MECHANICA
analyses, the software evaluates the behavior of your part and the stresses
it experiences in terms of the constraints you apply.
Constraints can also be used to reduce model size by allowing you to take
advantage of symmetry.
Edge Constraints
Before you can run an analysis, you need to constrain your model. The
first step in applying constraints to your model is to select the type of
entity you want to constrain. The next step is to fill out the dialog box that
will determine how these entities will, or will not be allowed to move
during the analysis. After the form is filled out, a constraint icon that
graphically represents the allowable movements will be attached to the
entity and, at a glance, you can visually determine how your part is
constrained.
Constraint Icons
The constraint icon is comprised of 2 rows and 3 columns: the top row
represents translational DOFs, and the bottom row represents Rotational
DOFs. The 3 columns are X,Y, and Z (or R, θ, Z for cylindrical coordinate
systems). Each square represents one of the six DOFs. If one of the
squares in the icon is filled, that indicates that a particular DOF as been
fixed or assigned a fixed displacement value. If the square is not filled,
then the entity is free to move in that DOF. Notice how the information
from the data form was transferred to the icon.
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X Y Z
Translate Row Free Trans X Free Trans Y Fixed Trans Z
Rotate Row Fixed Rot X Fixed Rot Y Free Rot Z
Figure 1 The constraint icon.
• Solid models have only three DOFs that can be constrained (alltranslation). Shell models have six DOFs that can be constrained.
• If you constrain a surface, then you only need to constrain thetranslational degrees of freedom. With edges, you need to constrain thetranslational and rotational degrees of freedom.
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This constraint restrains the translations of
this surface in the X, Y and Z direction, and
the model is fully constrained.
This constraint restrains the
translation of this edge in
the X, Y and Z direction,
but the model is free to
rotate around the X-axis.
This constraint restrains the
translations of this edge in the
X, Y and Z direction, as well
as the rotation around X, and
the model is fully constrained.
Figure 2 Constraining the model.
Symmetry
Symmetry is a special application of constraints. A part is symmetrical if,
when cut into a section, every point reflected from the mirror plane is the
same. Every load, constraint, all the geometry, and the material properties
must be symmetrical in order to perform a valid symmetrical analysis.
Using symmetry reduces meshing and analysis time, as well as required
disk space.
Cyclic Symmetry
A cyclic symmetry constraint allows you to analyze a section of a
cyclically symmetric model that simulates the behavior of the whole part
or assembly. This relational constraint reduces meshing and analysis time.
The original model (part or assembly) that you take a section of must
exhibit cyclic symmetry. That is, copying the cut section about a common
axis a specified number of times reproduces the whole model. (The
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number of times must be an integer.) The model must exhibit cyclic
symmetry in all of the following:
• Geometry
• Loads
• Other constraints
• Material type and orientation
In Pro/MECHANICA, a cyclic symmetry constraint prescribes rotation
and displacement on two boundaries to be the same. In Thermal, a cyclic
symmetry constraint prescribes the temperature distribution on two
boundaries to be the same.
Singularities
Constraints and loads should usually be applied to an entity with area. If
you constrain or load an entity with no area, then stress in your model can
theoretically go to infinity. Recall that the basic equation for stress is:
Stress = Load/Area.
For solid models, surfaces, or regions of surfaces constitute area. For shell
models, surfaces, regions, and edges constitute area. Why do edges have
area in a shell model? For shell compressed models, edges are at the
midsurface of the shell that have a defined thickness. Therefore the “area”
of an edge is the length of the edge times its thickness.
For both solid and shell compressed models it is not recommended that
you constrain points; because in both cases the points have no area. The
following table lists entities that should and should not be constrained or
loaded.
Table 1 Constraining various entities.
Shell Solid
Point NO NO
Edge OK NO
Surface OK OK
As the area approaches zero, the smallest of loads will cause
unrealistically high stress in your model. However, this may not be of
concern if your interest is only in deflections.
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If you apply constraints to datum points or curves, be aware of the
following:
• Point constraints can introduce high stresses and poor stress accuracyin both solid and shell models.
• Curve constraints can introduce high stresses and poor stress accuracyin solid models.
If you cannot avoid a point or curve constraint, and this situation concerns
you, you can work with your model in Linked Mode. Linked Mode
enables you to exclude a small set of elements around the constrained
geometry, thus preventing the stress concentrations from affecting the
analysis.
To avoid stress concentrations in Integrated Mode, you can define a small
region and apply the constraint or load to that region.
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LABORATORY PRACTICAL
Goal
To create model constraints.
Method
In Exercise 1, you fix the edge of a plate by applying an edge constraint to
the specified edge.
In Exercise 2, you apply point constraints to remove all six DOFs from themodel.
In Exercise 3, you apply constraints to a surface of the plate.
In Exercise 4, you create a cyclic symmetry constraint.
In Exercise 5, you learn how to correctly apply constraints to shell models.
In Exercise 6, you learn how to create User Defined Coordinate Systems
and to apply constraints with respect to the new coordinate system.
EXERCISE 1: Using Fixed Edge Constraints
Task 1. Fix the edge of a plate from translating in the Z-direction and
rotating with respect to the X and Y axes. All other Degrees Of Freedom
(DOFs) will be free.
1. Set your working directory to the folder that corresponds to the
name of the current module, and open the PLATE.PRT.
2. Enter Pro/MECHANICA. Click Applications > MECHANICA.
Click Continue in the UNIT INFO window.
3. Apply a constraint. Click Structure > Model > Constraints >
New > Edge/Curve.
4. The constraints dialog box appears. Enter [edge_constraint] for
Constraint name, and leave ConstraintSet1 as a Set name.
5. Click the curve arrow to select the edge. Select the edge of the
plate as shown in the following figure, followed by Done Sel.
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NOTES
Figure 3 Select the edge.
6. Keep WCS as the coordinate system.
7. Free Trans. X, Trans. Y, and RotZ. Fix all other Trans. and Rot.
The dialog box should look like the following figure.
Figure 4 The finished constraint dialog-box.
8. Click OK to complete the constraint.
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EXERCISE 2: Using Point Constraints
Task 1. Delete the edge constraint.
1. Delete the constraint you just created. From the constraint menu
click Delete and select the constraint icon.
2. Click Done/Return.
Task 2. Create datum points at the locations to constrain.
1. Click Model > Features > Datum Point > Create > On Vertex.
2. Select the three vertices shown in the following figure, followed by
Done Sel > Done > Done Return.
DTM Point 1
DTM Point 2
DTM Point 3
Figure 5 Constrain the vertices of the model.
Task 3. Constrain the first point.
1. Click Constraints > New > Point from the STRC MODEL menu.
2. The CONSTRAINT dialog box appears. Enter [Constraint_1]for the constraint name.
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NOTES
3. Leave the default name for the constraint set name,
ConstraintSet1 .
4. Click on the arrow for points. Pick the top left point, PNT0, and
click Done Sel.
5. Keep WCS as the coordinate system.
6. Fix all the translational DOFs and free all the rotational DOFs, as
shown in the following figure. This constraint removes all
translational DOFs, but the part is still free to rotate around the X,
Y, and Z axes.
Figure 6 Constrain the first point.
7. Click OK to close the dialog-box.
Task 4. Constrain the second point.
1. Click New > Point.
2. Enter [Constraint_2] for the constraint name.
3. Leave the default name for the constraint set name,
ConstraintSet1 .
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4. Click on the arrow for points. Pick the bottom left point, PNT1,
and click Done Sel.
5. Keep WCS as the coordinate system.
6. Fix only the X and Z translations.
7. Leave the Y Translation and all three rotational DOFs free as
shown in the following figure.
Figure 7 Constrain the second point.
8. Click OK.
Task 1. Create a point constraint for the third point.
1. Repeat the above steps to constrain the lower right point.
2. Fix point PNT2 only in the Z translation as shown in the following
figure. (Even though this constraint scheme does not explicitly
remove a rotational DOF, the two bottom points cannot translate in
the Z direction, which removes rotation around the Y-Axis.)
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NOTES
Figure 8 Constrain the third point.
Note:
The three translational constraints have removed all six DOFs,
including rotations, even though a rotational box was never
explicitly fixed in any of the CONSTRAINT dialog boxes. It is
not necessary to explicitly fix each DOF in a CONSTRAINT
dialog box in order to remove all six DOFs from a model.
2nd
Constraint removes X and Z
rotations
1st Constraint removes all
translations.
3rd
Constraint
removes Y
rotation
Figure 9 The constrained model.
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EXERCISE 3: Using Surface Constraints
Task 1. Delete the three point constraints.
1. Click Constraints > Delete and click each Constraint icon.
2. Repaint the screen. Click View > Repaint.
Task 2. Create a surface constraint.
1. Click New > Surface.
2. The CONSTRAINT dialog box appears. Leave Constraint1 as
the default constraint name.
3. Leave the default name for the constraint set name,
ConstraintSet1 .
4. Click on the arrow for surface. Select the vertical sides of the plate
and then click Done Sel.
5. Keep WCS as the coordinate system.
6. Fix all the translational DOFs.
7. Leave the rotational DOFs free.
8. Click OK.
9. Click Applications > Standard. Click File > Save and Window
> Close.
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EXERCISE 4: Constraining Shell Models
Task 1. Apply constraints to shell models using the T-Bracket in order
to hold the two ends of the T-Bracket fixed in all DOF for the model.
1. Open the T_BRACKET.PRT and verify that the units are mmNs.
2. Enter MECHANICA Structure.
3. Click Structure > Model > Idealizations.
1. Define the surface pairs and test the midplane compression. ClickShells > Midsurfaces > AutoDetect > Compress > Shells only
> ShowCompress. The model should appear as in the following
figure.
2. Click Done > Done Return > Done Return.
Figure 10 The compressed bracket.
Note:
The first step to constraining a part is to think about how this
part will actually be held in place. Then, apply the appropriate
constraints to the model. In this example, the part is welded on
the right and left edges of the base into a larger assembly.
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Task 2. Fully constrain the two vertical surfaces of the t_bracket.
1. Click Constraints > New > Surface.
2. Enter [Constraint_1 ] for the constraint name.
3. Leave the default name for the constraint set name,
ConstraintSet1 .
4. Click on the arrow for surface. Pick the right and left vertical
surfaces as shown in the following figure. Click Done Sel.
Figure 11 Surface Constraints
5. Keep WCS as the coordinate system.
6. Fix all DOFs in the dialog box and accept the form.
7. Click OK.
8. Switch to the standard application.
9. Save and erase the model.
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EXERCISE 5: Using Coordinate SystemConstraints
Task 1. Create a cylindrical coordinate system aligned with the hole to
define a constraint with respect to.
1. Retrieve the T_BRACKET_HOLE.PRT.
2. Click Applications > MECHANICA > Continue > Structure.
3. Click Model > Features > Coord System > Create > 2 Axes >
Cylindrical > Done.
4. When prompted for the first axis, pick the axis of the first hole.
This reference partially defines the orientation and location of the
coordinate system.
5. When prompted for the second axis, pick the top edge of the plate
as shown in the following figure. With the second reference, the
location of the coordinate system is fully defined.
Figure 12 Select the edge to define the coordinate system.
6. A red arrow pointing downward will appear. Select Z-Axis to
define Z direction.
7. Another arrow is highlighted in red. Select the default Theta=0 to
define the starting point of the Theta direction. The cylindrical
coordinate system is fully defined.
8. Repeat for the other hole to create CS1. Reverse the direction of the
Z-axis arrow as necessary, so that it has the same direction as CS0.
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9. Click Done/Return.
Task 2. Simulate bolted bracket by constraining the edges of the holes.
A bolt in a threaded hole allows the hole to displace radially, but not
translate along or rotate around the bolt.
1. Click Constraints > New > Edge/Curve.
2. In the CONSTRAINT dialog box, enter [bolt1] as the name.
3. Click on the [select] under the CURVES. Select the two top
edges that define the top of the right hole and click Done Sel.
4. Click on the [select] under the COORDINATE SYSTEM. Select
corresponding cylindrical coordinate system, followed by Done
Sel.
Note:
Constraints and Loads are always applied with respect to a
current coordinate system. The Mechanica World Coordinate
System (WCS) is the default. In this case, local coordinate
systems are referenced when constraining the model.
5. Free R and fix other Degrees of Freedom.
6. Click OK to finish.
7. Constrain the second hole on the left hole using the same
procedure and name it [bolt2].
8. Switch to standard application.
9. Save and erase the model.
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NOTES
EXERCISE 6: Using Cyclic Symmetry Constraints
Task 1. Create the cyclic symmetry constraint.
1. Retrieve the WHEEL.PRT.
2. Investigate the last cut by redefining it.
3. Quit redefining without changing anything.
Note:
The wheel part is cyclically symmetric. The last cut is created
to remove geometry, as shown in the following figure. The
geometry you are going to perform analysis on is the one slice
of the entire model.
Figure 13 The cyclic symmetric wheel.
Task 2. Create the cyclic symmetry constraint.
1. Click Application > Mechanica. Click Continue in the UNIT
INFO dialog box.
2. Click Structure from the MECHANICA menu.
3. Click Model > Constraints > New > Cyclic Symm.
4. Click the [Select] icon right next to the FIRST SIDE. Select the
one pie cut surface as the FIRST SIDE as shown in the following
figure. Click Done Sel to finish.
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5. Using the same procedure to select the other pie cut surface as the
SECOND SIDE, as shown in the following figure.
Second Side
First Side
Figure 14 Select the indicated surface to create the cyclic constraint.
6. Click OK to finish.
7. Switch to the standard application.
8. Save and erase the model.
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MODULE SUMMARY
You have learned:
• How to define different types of constraints.
• How to create user defined coordinate systems.
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Module
Simulating Applied LoadsIn this lesson, you learn how to apply the different types of loads
available in Pro/MECHANICA.
Objectives
After completing this module, you will be able to:
• Create different load types.
• Describe the difference between point, edge, and surface loads
• Describe when to use each load type.
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INTRODUCTION
For Pro/MECHANICA to perform most types of analyses, you must load
at least one area of your model. Pro/MECHANICA provides a wide
variety of load types. Below is a list of the types of loads that
Pro/MECHANICA STRUCTURE supports:
• Point • Edge/Curve • Face/Surface
• Bearing • Centrifugal • Gravity
• Pressure • Temperature
Pro/MECHANICA THERMAL supports:
• Heat Loads
You can define as many loads for your model as you like. When you apply
loads in Integrated Mode, Pro/MECHANICA associates the loads with
part geometry, rather than the elements it will create during the analysis
phase.
Before you add loads to your model, be sure you have the geometry and
references you need already in place. Pay particular attention to the
following items:
• Coordinate Systems – If you plan to make a Structure load relativeto any coordinate system other than the World Coordinate System
(WCS), then you must have that coordinate system in place and active.
• Datum Points – If you plan to load a specific point on an exterior
curve or surface, then your part must include a datum point at that
location. Be aware that point loads can introduce high stress
concentrations or theoretically infinite thermal fluxes in your model.
• Regions – If you plan to load a specific surface region, your modelneeds to include the datum curve contours that define the region.
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LABORATORY PRACTICAL
Goal
To create different types of loads on a model.
Method
In Exercise 1, you apply Point, Edge, and Surface Loads. You also review
and verify the created loads.
In Exercise 2, you investigate some of the spatial variations that you canassign to loads using linear, quadratic, and cubic interpolation options.
In Exercise 3, you explore how to apply a load using Direction and
Magnitude.
In Exercise 4, you apply a pressure load that varies as a function of a
coordinate system. You also apply a gravity load.
In Exercise 5, you will create a load distribution using the Total Load at
Point Option.
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EXERCISE1: Applying General Loads
Task 1. Create datum points on the T-Bracket to prepare for loads
creation.
1. Set your working directory to the folder that corresponds to the
name of the current module.
2. Open T_BRACKET_HOLE.PRT.
3. Enter Pro/MECHANICA. Click Applications > MECHANICA >
Continue> Structure.
4. Turn off the display of the constraint symbols.
� Click View > Simulation Display > Visibilities.
� Unselect the constraint sets from the LOAD/CONSTRAINT
SETS list and click OK to finish.
5. Click Model > Features > Datum Point > Create > On Vertex
and add four datum points to the vertices shown in the following
figure.
Figure 1 Points Created For Applying the Load
6. Click Done Sel > Done > Done/Return. Assume for now that you
will model this part as a solid.
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Task 2. Create a point load.
1. Click Loads > New > Point.
2. A FORCE/MOMENT dialog box appears. Click New to create a
new load set. A LOAD SET dialog box appears.
3. Enter [point_load ] as the load set name and click OK.
4. Enter [point0 ] for the load name.
5. Click [Select] under the POINTS and select PNT0. Click Done
Sel.
6. Keep the default coordinate system WCS.
7. Enter [–10 ] for the Y component. Click OK to finish. Note the Load
icon at point PNT0.
Note:
If it is necessary to apply point or curve loads on a solid
model, and the potential effects of this concern you, you can
work with your model in Independent Mode instead. This
mode enables you to exclude elements around the loaded
geometry, thus preventing infinite stress concentrations from
affecting the analysis.
Point loads can introduce theoretically infinite stresses and
distort your results for both solid and shell models.
Curve loads can introduce theoretically infinite stresses and
distort your results for solid models.
To avoid stress concentrations in Integrated Mode, you can
define regions and apply the load to the region instead of the
point or curve.
Task 3. Review the load you applied to the model.
1. Click Rev Tot Load.
2. When the system prompt for the point, select the datum point
PNT0, where you just applied the load.
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3. When prompted for a load to review, click the load symbol for the
point load you just created, followed by Done Sel.
4. The LOAD RESULTANT dialog-box appears. It shows the
summary of the resultant load on the point due to the point load.
Review the dialog-box. Notice that the moments are zero, due to
the zero moment arm.
5. Repeat reviewing the resultant load at PNT1, PNT2, and PNT3 due
to the point load PNT0.
6. Notice that FY is -10 for all the points. The values of the moments
change due to the change of the moment arm.
Task 4. Apply an edge load.
1. Click New > Edge/Curve.
2. A FORCE/MOMENT dialog box appears. Click New to create a
new load set. A LOAD SET dialog box appears.
3. Enter [edge_load ] as the load set name and click OK.
4. In the FORCE/MOMENT dialog box, enter [edge_load1 ] for the
load name.
5. Click [Select] under the CURVES and select edge, shown in
the following figure. Click Done Sel.
6. Keep the default coordinate system WCS.
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Figure 2 Apply load at the indicated edge.
7. Enter [–1] for the X component. The total load of 1 N is uniformly
distributed over the entire edge, producing a unit load of 0.004
N/mm. (The edge length is 250 mm.)
8. Preview the load. Click OK to finish.
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EXERCISE 2: Applying Spatial Load Variations
Task 1. Edit the edge load to linearly interpolate over the edge length.
1. Click the edge load icon, it should turn red.
2. Right-click the edge load icon and choose Edit. Pro/MECHANICA
highlights the referenced coordinate system and edge. The
FORCE/MOMENT dialog box appears.
3. Change the distribution. Click the second DISTRIBUTION drop-
down list and change from Uniform to Interpolated Over Entity.
4. Click Define, the INTERPOLATION OVER ENTITY dialog-box
appears.
5. Enter [0] for point 1 and [1] for point 2. Click Preview, the load
appears as shown in the following figure.
6. Click OK from the interpolation dialog-box and click OK from the
FORCE/MOMENT dialog box. Note: the load icon still remains
even though you selected Interpolated over Entity.
Figure 3 Interpolate over two points.
Task 2. Review the resultant load at the 4 datum points.
1. Click Model > Loads > Rev Tot Load.
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2. Select any one of the four datum points when prompted for point.
3. Click the edge load icon from the model, followed by Done Sel.
4. The Load Resultant dialog-box should report FX = -1. Try
reviewing the load at the other datum points. FX should remain a
constant -1, but the moments will vary.
5. Check the load's value at Point 2.
6. Click Done Sel > Done Return > Done Return.
Task 3. Create three additional datum points on the edge to use as
interpolation points.
1. Click [Insert datum point].
2. Click On Curve > Length Ratio.
3. Click the edge you just applied the load to and click Done Sel.
4. Enter [0.25 ] for the curve length ratio.
5. Repeat to add points at [0.5 ] ratio and [0.75 ] ratio along the
curve.
6. Click Done to finish. The bracket should look like in the following
figure.
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NOTES
Figure 4 Create three interpolation points.
Task 4. Edit the edge_load to change its interpolation scheme to
quadratic.
1. Click the edge load icon, it should turn red.
2. Right-click the edge load icon and choose Edit. The
FORCE/MOMENT dialog box appears.
3. Define the distribution. Click Define.
4. In the INTERPOLATION OVER ENTITY dialog-box, click ADD.
5. When prompted for an interpolation point, click the datum point in
the center of the curve, PNT5, and click Done Sel > Done/Return.
6. Enter [0], [0], [1] for the interpolation point values.
7. Click Preview and note the parabolic distribution of the load along
the edge shown in the following figure.
Figure 5 Parabolic distribution.
Task 5. To develop a cubic interpolation, add additional datum points to
the edge.
1. Click ADD, in the INTERPOLATION OVER ENTITY dialog-box.
2. Click the datum point at 0.25 ratio (PNT4) to the interpolation.
3. Click ADD to add the datum point at 0.75 ratio (PNT6) to the
interpolation. Read the error message.
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NOTES
Note:
When you try to add the 5th interpolation point, you get an
error message. Only 4 points are allowed for interpolated
loads.
4. Click OK to acknowledge the error message.
5. Now set the values for the four remaining points as shown in the
following figure.
Figure 6 fill in the dialog-box.
6. Click Preview and note the cubic distribution as in the following
figure.
Figure 7 Define a cubic interpolation.
7. Click OK from the interpolation dialog-box to complete the review.
Note that the total load is still 1.
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NOTES
Note:
For the Interpolated option of Spatial Variation, specifying two
points results in a linear interpolation, three points in a
quadratic interpolation, and four points in a cubicinterpolation.
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NOTES
EXERCISE 3: Varying Load Direction andMagnitude
Task 1. Enter the edge_load directions and then input a magnitude in
the Load dialog-box.
1. In the FORCE drop-down list, change from Components to Dir
Vector & Mag.
2. Enter [-1 ] for FX, [1] for FY and [10] for the Mag.
3. Click Preview to review the resulting load distribution, and note
how it is now at a 45°°°° angle to the XZ plane as shown in the
following figure. Click OK to accept the Load.
Figure 8 Preview the Load Distribution
Note:
If Components is used to define the same load, the values of
the components are ( )
071.72
102
=== FyFx
4. Verify the components of the direction and magnitude load you
just applied
� Click Model > Load > Rev Tot Load.
� Select any datum point.
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NOTES
� Select the edge load.
� Click Done Sel. The Load Resultant dialog-box should report
Fx = -7.071 and Fy = 7.071 N.
� Click OK to finish.
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NOTES
EXERCISE 4: Using Pressure and Gravity Loads
Task 1. Apply a pressure load on the right side of the vertical plate. This
load will vary with the square of the distance along the Y-axis.
1. Click [Create a pressure load].
2. A PRESSURE dialog box appears. Click New to create a new load
set.
3. Enter [surface_load ] for the load set name. Click OK.
4. Enter [surface_load1 ] for the load name.
5. Click [Select] and select the surface on the right side of the
bracket and click Done Sel.
Figure 9 The Finished Pressure Load Dialog Box
6. From the DISTRIBUTION drop-down list, select Function of
Coordinates.
7. Define the magnitude. Enter [1] for the P.
8. Click f(x) to define the distribution. The FUNCTIONS dialog box
appears.
9. Click on New. The FUNCTION DEFINITION dialog box appears.
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NOTES
10. Enter [y_squared ] for name.
11. Select Symbolic from TYPE drop-down list. Enter [y^2 ] as the
function as shown in the following figure.
Figure 10 Define a load function.
Task 2. Review the function.
1. Click Review, followed by Graph.
2. Enter [12.5 ] as the lower limit (the bottom of the vertical surface)
and enter [250] for the upper limit (the top of the vertical surface).
3. Display the distribution. Click Graph.
4. Zoom in and expand a portion of the graph. Click Utilities > Seg
Graph and select any two points on the graph.
5. Display the full graph. Click Utilities > Full Graph.
6. Display the exact value at a specific point. Click Utilities > Point
Query and select any point. Click OK to confirm.
7. Click File > Exit Graphing when finish.
8. Click Done > OK > OK.
9. Click Preview to view the load distribution. The model should
look like the following figure.
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NOTES
10. Click OK to finish.
Figure 11 Preview the pressure load.
Task 3. Apply a gravity load to your part.
Note:
In a lot of cases, the gravity load is negligible in magnitude
relative to the applied loads; however, vibration analyses, in
particular, often rely on heightened gravity loads to simulate
drop or shock conditions.
1. Click [Create gravity load].
2. The system reminds you that the gravity load is always applied
using the WCS. Click OK.
3. Create a new load set. In the GRAVITY dialog-box, click New.
4. Enter [gravity ] as the Load Set name. Click OK to finish.
5. Enter [gravity1 ] as load name.
6. Enter [-0.00981 ] for Y.
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7. Click OK to accept the dialog-box. .Notice the addition of the G
icon at the default coordinate system origin.
8. Switch to the standard application. Save and erase the model.
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NOTES
EXERCISE 5: Creating Load Distributions
Task 1. Retrieve CRANK.PRT and create datum points on the crank to
prepare for load creation.
1. Retrieve the CRANK.PRT.
2. Click Application > Mechanica > Continue > Structure.
3. Click [Insert datum point].
4. Select the At Center from the DATUM POINT menu.
5. Click the edge as shown in the following figure.
Figure 12 Create a datum point at the center of the indicated edge.
6. Click Done Sel > Done to finish.
7. Create another point offset from the point you just created.
� Click [Insert datum point].
� Select the Offset Point from the DATUM POINT menu,followed by Plane Norm.
� Click the surface as the offset plane reference, as shown in the
following figure. Click Done Sel to finish.
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NOTES
Figure 13 Select the indicated surface as the offset reference.
� Click the point you just created as the point reference. Click
Done Sel to finish.
� Enter [3] as the offset value.
8. Click Done to finish.
Task 2. Create a surface load with the Total Load at Point
DISTRIBUTION option.
1. Click Model > Loads from the STUC MODEL menu.
2. Click New > Surface.
3. Click the [Select] icon under SURFACE(S) and select the hole
surfaces as shown in the following figure.
Figure 14 Select the load surface.
4. Accept the default world coordinate system WCS.
5. Select Total Load at Point from the DISTRIBUTION drop down
list.
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NOTES
6. Select the second point you created as shown in the following
figure.
Figure 15 Select the point for load distribution.
7. Enter [350 ] for the F Z. The dialog box should look like the
following figure.
Figure 16 FORCE/MOMENT dialog box.
8. Preview the load and close the dialog box.
9. Save and erase the model.
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NOTES
MODULE SUMMARY
You have learned:
• How to create different types of loads.
• How to create Interpolated and Function of Coordinates spatiallyvarying loads.
• How to create a load distribution using Total Load at Point option.
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Page 7-1
Module
Running and Evaluating AnalysesIn this module, you define and run an analysis, and evaluate your
results. You learn the differences between Single-Pass Adaptive and
Multi-Pass Adaptive analyses. You also learn how to define run
settings and RAM allocations.
Objectives
After completing this module, you will be able to:
• Set up models for analysis.
• Combine structural and thermal analyses.
• Describe the difference between Single-Pass Adaptive and Multi-Pass Adaptive analyses.
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NOTES
INTRODUCTION
For this exercise, assume that you are working for a toilet manufacturer
who is developing a new portable toilet unit. You are assigned the task of
developing inexpensive seat for the unit. You want to use readily available
materials capable of surviving a harsh outdoor environment; additionally,
the seat must support a 1570 N (160 kg) load without excessive
deformation or stress.
Analysis Options
An analysis is the calculation of your model's response to its boundary
conditions. Pro/MECHANICA STRUCTURE/THERMAL provides 12 types
of analyses that span a wide range of actual experimental conditions. The
following table lists the analysis types.
Analysis Type Product Use it to find
Static Structure Stress/displacements of the structure
Modal Structure Natural frequencies and mode shapes of the
structure (eigenvalues and eigenvectors)
Pre-stress Static Structure Stress/displacements of the pre-stressed
structure
Pre-stress Modal Structure Natural frequencies and mode shapes of the pre-
stressed structure
Buckling Structure The multiplication factor for the load that will
make the structure buckle, and buckle shape.
Contact Structure Possible contact area and pressure. Stresses and
displacement as a function of loading.
Dynamic Time Response Vibration Response versus time of the structure given any
general time or varying load.
Dynamic Frequency
Response
Vibration Response versus frequency of the structure
given any periodic (frequency varying) load.
Random Vibration Vibration Response versus frequency of the structure
given any Power Spectrum Density input. (PSD)
Shock Response Vibration Response versus time of the structure given any
general shock loading condition.
Steady-State Thermal Thermal Temperature throughout the structure given heat
loads, and convection conditions
Transient Thermal Thermal Temperature throughout the structure given
time-varying heat and/or convection conditions.
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NOTES
LABORATORY PRACTICAL
Goal
To define an analysis, run the analysis, and review the results.
Method
In Exercise 1, you are concerned with the comfort of the seat design.
Therefore, you perform and determine the resulting temperatures, thermal
deformations, and stresses.
In Exercise 2, you define a thermal analysis on the seat. A steady-state
thermal analysis calculates thermal response to specified heat load, subject
to specified prescribed temperatures and/or convection condition. Since all
Pro/MECHANICA modules (Structure, Thermal, and Motion) share a
common database, you do not have to reassign the material properties.
You only need to set up the thermal boundary conditions and define the
thermal analysis.
In Exercise 3, you set up a combined thermal and structural static analysis.
Assuming you already have a defined thermal analysis, this is a four steps
process that requires a special load type called a MEC/T load.
In Exercise 4, you develop three Load Sets: the mechanical load, the
temperature load, and the combined temperature/mechanical load. This
ensures convergence on the combined loading, but also allows you the
flexibility of superimposing and scaling the results from each load set in
the post-processor.
In Exercise 5, you learn about the difference between Single Pass
Adaptive and Multi Pass Adaptive convergence algorithms methods
through the seat example. You create a Multi-Pass static analysis and
compare the resulting answers with those of a Single-Pass.
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NOTES
EXERCISE 1: Running a Structural Analysis
Figure 1 A symmetric toilet seat is cut in half.
Task 1. Retrieve the seat model. Create datum curves for region
creation.
1. Set your working directory to the folder that corresponds to the
name of the current module.
2. Open SEAT.PRT.
Tip & Technique:
The model in the preceding figure is symmetric about DTM1
in terms of geometry, properties, constraints, and loads;
therefore using symmetry is recommended. Symmetry takes
advantage of the fact that important model features and
boundary conditions are symmetric about a plane.
3. Insert a datum curve by clicking [Insert a sketched curve].
4. Select the top surface of the seat and click Okay.
5. Select BOTTOM and pick DTM3 datum plane.
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NOTES
Figure 2 Sketch the section with two dimensions.
6. Click [Done] to finish, then click OK.
Task 2. Create a datum plane referencing DTM3. This datum plane will
be used in the region creation.
1. Click [Insert a datum plane].
2. Click Through, set the filter to AxisEdgeCurv.
3. Display axis as necessary. Click the A_1.
4. Click Angle, select DTM3, and click Done.
5. Click Enter Value and enter [-55 ].
Task 3. To create the first support's datum curve.
1. Insert a datum curve by clicking [Insert a sketched curve].
2. Select the bottom surface of the seat.
3. Remove the default references and specify DTM4 and A-1 as the
references.
4. Sketch a circle with the center aligned to the DTM4.
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NOTES
5. Create the dimension scheme referencing the datum axis, as shown
in the following figure.
6. Click [Done] to finish.
Dimension to the
Datum AxisAlign the
sketched circle
to DTM4
Figure 3 Dimension the circle.
7. Repeat the procedures to create a second datum plane and curve 45
degrees from DTM3, the sketch should look like the following
figure.
Figure 4 Create the second datum curve.
8. Save the model.
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NOTES
Task 4. Enter MECHANICA and create the regions.
1. Enter MECHANICA. Click Applications > Mechanica >
Continue > Structure.
2. Add the regions to the model, before defining the surface pairs.
3. Click Features > Surf Region > Create > Select > Done.
Tips & Techniques
You can also sketch a Region directly in Pro/MECHANICA
using Features, Surf Region from the STRC MODEL
menu then using Sketch instead of Select option.
4. Select one of the two circles representing the seat's support.
5. Select the bottom surface as the surface to split. Click Done Sel >
Done > OK.
6. Repeat the procedures to define the region on the bottom surface
with the other circle.
7. Repeat the procedures to define the region on the top surface.
8. Click Done/Return to finish.
9. Visualize the surface regions.
� From the VIEW pull-down menu, click Model Setup > Mesh
Surface.
� Click inside the circles. The model should appear as shown in
the following figure. Select Close to complete.
Figure 5 Visualize the regions.
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NOTES
Task 5. Compress the midsurfaces
1. Click Done/Return.
2. Click Model > Idealization > Shells > Midsurfaces > New.
3. Select all five surfaces to be projected onto the compressed
midsurface.
� Select the three new regions
� Then select the two larger remaining surface areas on the top
and bottom of the seat, followed by Done Sel.
4. Click Compress > Shells only > Show Compress. The model
should appear as shown in the following figure.
5. Click Done > Done/Return > Done/Return.
Figure 6 The compressed midsurface with regions.
Task 6. Assign the material properties.
1. Click Model > Materials, the MATERIAL dialog box appears.
2. Select PVC from the Materials in Library column and click on the
right arrows to place it in MATERIALS IN MODEL column.
3. Click Assign > Part and click the model, followed by Done Sel.
4. Click on Edit while PVC in highlighted in MATERIALS IN
MODEL column.
5. Click Thermal tab. For the thermal conductivity value, type
[0.667527 ].
6. Click OK > Close.
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NOTES
7. Save the model.
Task 7. Apply the support constraint.
1. Apply the support constraints that restrain the seat from moving up
and down. Click Constraints > New > Surface. The
CONSTRAINT dialog-box appears.
2. Click [Select] the two small circular surfaces on the bottom of
the seat representing the supports using Query Sel, followed by
Done Sel.
3. Fix the Y translation only, leaving all other DOFs free, followed
by OK.
Task 8. Apply the hinge constraint.
1. Click New > Edge/Curve.
2. Click [Select]. Select the edge as shown in the following
figure, followed by Done Sel.
Figure 7 Constrain the back edge to simulate the hinge.
3. Free the TransX and RotX and fix all other DOFs, followed by OK.
Task 9. Apply the symmetric constraint to the edge/curve on the cutting
plane.
1. Click New > Edge/Curve.
2. Click [Select]. Select the two top edges on the cutting plane,
followed by Done Sel.
3. Fix X translation, Y and Z rotations. Leave others free.
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NOTES
Note:
Since the cutting plane is in the Y-Z direction, the direction
normal the TransX must be fixed. However, an object is free to
move horizontally and/or vertically meaning TransY and
TransZ must be free. Rotation is more difficult to imagine. Of
course, RotX is allowed because you are free to spin an object
as long as its spin axis is normal to the mirror. However, if you
try to spin that object in RotY or RotZ, the object will try to
pass through the symmetry plane, which is not allowed.
Therefore, RotX is free while RotY and RotZ are fixed.
4. Click OK > Done/Return when finished. The model should appear
as shown in the following figure.
Figure 8 The fully constrained seat.
Task 10. Load the seat, designing it to support a 160 kg user. Apply a 80
kg which corresponds to 785 N load to the cheek region.
1. Click Loads > New > Surface.
2. The FORCE/MOMENT form appears, for the load name enter
[one_cheek ].
3. Create a new load set. Click New and enter [one_cheek ],
followed by OK. You have created a load one_cheek and a load set
one_cheek.
4. Click [Select]. Select the cheek region, followed by Done Sel.
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NOTES
5. Apply a total load of 785 N, uniformly distributed over the region
in the negative Y direction. Enter [-785 ] for Y FORCE component,
followed by OK > Done/Return.
Task 11. Set up a static analysis with the previous created loads and
constraints.
Tips & Techniques:
A static analysis calculates deformations, stresses, and strains
in your model in response to specified constraints and loads. A
static analysis tells you if your model will withstand stress or
break, where the part will break, and how much the part will
move.
1. Click Analyses from the MEC STRUCT menu.
2. The ANALYSIS dialog box appears, select Static and click New.
3. The STATIC ANALYSIS DEFINITION form appears, for the name
Enter [static_seat ].
4. For description, enter [Static analysis of the seat with
a 160 Kg person on it ].
5. Verify that the Constraintset1, one_cheek, are highlighted. Un-
highlight LOADSET1 as necessary.
6. Click on Convergence Tab and select Single-Pass Adaptive.
7. Click on Output Tab and set the Plotting Grids to 7.
8. Click OK > Close to finish.
Task 12. Create a standard design study by running multiple analyses on
a single part.
Tips and Techniques:
You can group analyses together under one standard design
study, and just run the study. If you are running multiple
analyses on a model, this may make file management easier.
The results from all the analyses will be contained within a
single design study result directory.
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NOTES
1. Click DesignStudies from the MEC STRUCT menu. The
DESIGN STUDY DEFINITION dialog box displays.
2. For the Study Name, enter [standard_seat ].
3. For the description, enter [Design Study to run a static
analysis of the seat ].
4. For the Analyses, select static_seat.
5. Click Accept followed by Done.
Task 13. Run your study.
1. Click Run from the MEC STRUCT menu.
2. Accept the default Standard_seat(Standard) design study.
3. Click Settings.
4. Change the RAM allocation.
� Click Settings and select Ram Allocation.
� Change it to half the RAM on your machine. (Consult the
instructor as necessary.)
� Click Accept.
Task 14. Start the analysis run and check the Run Status.
1. Click Start.
2. Click Yes when prompted for error checking.
3. Click Summary to monitor the progress of your design study.
4. Click Close > Done when the run is finished.
Task 15. Review the results by creating a fringe plot of stresses.
1. Create a RESULT window. Click Results from the MEC STRUCT
menu.
2. Click No when prompted whether you want to save the model. The
result interface is displayed.
3. Create a window to display the stress.
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NOTES
� Click [Insert result window].
� Enter [vm_static ] as the name, followed by Accept. The
DESIGN STUDY dialog box appears
� Click the Standard_Seat\ in the CURRENT DIRECTORY.
� Click Accept to finish.
4. Define the result window contents. In the DEFINE CONTENTS
FOR RESULT WINDOW “MAX_PRINCIPAL” dialog box,
� For the Title, enter [Static Analysis Von Mises
Stress on Seat ].
� For Quantity, select Stress > Total > von Mises.
� For LOCATION, select All > Maximum > of shell top/bottom.
� For DISPLAY, select Fringe and clear the Continuous Tone
and Average.
� Accept the Deformed scale 10%.
� Select Animate. Change the number of frames to 16 .
Note:
More frames will result in smoother animation and take longer
to generate.
� Select Auto Start and Reverse.
� Click Accept and Show.
5. Use following icons to play and control the result animation:
� [Stop]; [Play]; [Single Step]; [Single Step
Back].
� Stop the animation when finish.
Task 16. Create an animation of the seat displacement. The quickest way
to create a result window that is referencing the same study or analysis as
a result window that has already been defined, is to copy the predefined
results window and then edit its contents.
1. Click [Copy window].
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NOTES
2. Enter [disp_animate ] as the name, followed by Accept.
3. Fill out the dialog-box as shown in the following figure.
Figure 9 Define a displacement result window.
4. Click Accept.
Task 17. Generate a third result window to display the displacements
along the outer edge of the seat.
1. Stop the current animation if necessary. Click [Copy window].
2. Enter [edge_disp ] as the name, followed by Accept.
3. Fill in the dialog-box as shown in the following figure.
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NOTES
Figure 10 Define another result window.
4. Click Select to define the LOCATION.
5. Reorient the model in 3D using the <Ctrl> key and the mouse
buttons.
6. Click the outer edge as shown in the following figure.
Select this edge.
Figure 11 Generate the displacement graph of the select the edge.
7. Click the middle mouse button to finish. Click OK when prompted.
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NOTES
8. Click Accept.
Task 18. Display multiple windows.
1. Click [Display Result Windows].
2. In the display result window dialog box, click [Select all],
followed by OK. The system starts to animate all animated
windows.
Note:
To control multiple animated windows simultaneously, selectthe windows using <Shift> first.
3. In the selected window, switch the model to the isometric view.
Click View > Spin/Pan/Zoom > Isometric > OK.
Task 19. Edit the legend of the stress result window. Assume the
maximum allowable stress is 35 Mpa. Display higher stress in red.
1. Select the stress result window. Click inside the stress result
window. The system highlights its boarder in yellow.
2. Click Edit > Legend Value.
3. Click the second value from the top in the legend.
4. Enter [35], followed by OK.
5. Click Yes when prompted for linear redistribution.
Task 20. Examine the displacements of the outer edge of the seat.
1. Select EDGE_DISP window.
2. Zoom in on a specific range of the plot.
� Click Utilities > Segment Graph.
� Pick any two points on the graph.
3. Display the entire graph, click Utilities > Full Graph.
4. Change the format of the table.
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NOTES
� Click Format > Result Window.
� Clear the Labels and Titles check boxes followed by OK.
Observe the changes in the window.
5. Write the graph data to a file on disk.
� Click File > Export > Graph Report.
� Save in the current directory. Enter [my_data ] for the file
name. Click Accept.
� Click No when prompted for saving the legend information.
Note:
Pro/MECHANICA will write the data to disk in an ASCII filewith a .GRT extension.
6. Click File > Exit Results. Answer No when prompted to save the
window.
7. Click Done/Return to return to the top-level menu.
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NOTES
EXERCISE 2: Defining Thermal Analyses
Task 1. Enter Pro/MECHANICA Thermal. Apply a heat load.
1. Click Thermal.
2. Click [Define a heat load on surface]. The HEAT LOAD dialog-
box appears.
3. Enter [thermal_load ] for the name.
4. Create a new load set.
� Click New for load set.
� Enter [therm_load ] as the load set name.
� Click OK.
5. Click [Select]. Select the two circular regions on the bottom of
the seat representing the supports using Query Sel. Click Done
Sel when finished.
6. Enter [-50 ] for Q.
7. Click OK to finish the load definition. Note the addition of the heat
load icons to the display.
Task 2. Apply the fixed temperature of 37° C to the cheek region.
1. Click [Prescribed temperature on surface].
2. Enter [body_temp ] for the name.
3. Create a new constraint set.
� Click New.
� Enter [thermal_const ] for the set name.
� Click OK.
4. Click [Select]. Select the cheek region on the top surface of
the seat. Click Done Sel when finished.
5. Enter [37]. Click OK to finish. Notice the addition of the fixed
temperature “T” icon.
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NOTES
Task 3. Apply the convection conditions.
1. Click [Surface convection condition]. The CONVECTION
CONDITION dialog box appears.
2. Enter [side_conv ] for the name.
3. Accept the default therm_const constraint set.
4. Click [Select]. Select the larger region on the bottom of the
seat followed by Done Sel. Do not select the small regions that
already have heat loads applied to them.
5. Enter [0.2 ] for the CONVECTION COEFFICIENT.
6. Enter [25] for the BULK TEMPERATURE to simulate 25 °C air.
7. Click OK to finish. Notice the addition of the convection icon.
Figure 12 Thermal boundary conditions.
Task 4. Define a thermal analysis.
1. Click Analyses. Accept the default Steady State type.
2. Click New. The STEADY THERMAL ANALYSIS dialog box
appears.
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NOTES
Figure 13 Define a thermal analysis.
3. Click OK > Close > Done/Return.
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NOTES
EXERCISE 3: Running Combined Analyses
Task 1. Create a MEC/T load for a static analysis. The temperature
distribution of the MEC/T load is the result of the previously defined
thermal analysis.
1. Click Structure > Model > Loads > New > Temperature >
MEC/T Temp.
2. Enter [temps1 ] as the name.
3. Create a new load set.
� Click New.
� Enter [temps ] as the name.
� Click OK.
4. Uncheck the “Use previous design study” if necessary.
5. Enter [25] for the Reference Temperature.
6. Click OK and note the addition of the MECT icon.
Task 2. Create a load set that contains both thermal and structural load.
First, create the thermal load in the set.
1. The thermal load in the combined load set is identical to the load
created in the previous task. Click New > Temperature > MEC/T
Temp.
2. Enter [temps2 ] as the name.
3. Create a new load set.
� Click New.
� Enter [mech_and_therm ] as the name.
� Click OK.
4. Uncheck the “Use previous design study” if necessary.
5. Enter [25] for the Reference Temperature.
6. Click OK and note the addition of the MECT icon.
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NOTES
Task 3. Create the structural load in the thermal/structural load set.
1. Click [Create a surface load]. The FORCE/MOMENT dialog-
box appears.
2. Enter [one_side ] as the load name.
3. Assign the load to the MECH_AND_THERM load set created in the
previous task. Select mech_and_therm from the load set drop-
down list as necessary.
4. Click [Select]. Select the cheek region, followed by Done Sel.
5. Enter [-785 ] for Y FORCE component.
6. Click OK. Note the addition of a new load icon in the cheek region.
The model should appear as shown in the following figure.
Note:
It may appear that the loads are doubled on the model. But as
you will soon see, you are not.
Figure 14 Apply a thermal/structural combined load set.
Task 4. Create a static analysis that calculates the thermal stresses as
well as the combined thermal/mechanical stresses.
1. Click Analyses.
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NOTES
2. Select Static > New.
3. Fill in the dialog box as shown in the following figure.
4. Click OK > Close.
Figure 15 Define analyses.
Task 5. Run the static analyses.
1. Click Run.
2. Select the analysis, THERMAL_MECH(STANDARD/STATIC).
3. Click Start.
4. Click Yes to when prompted for error detection.
5. Click Summary to monitor the progress of your runs.
6. When the analysis is finished running, scroll up through the
summary file and review the information for all four runs. Review
the Summary file carefully.
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NOTES
� How much disk space did it take?
� How long did it take?
� What is the maximum temperature in the seat?
� What is the maximum stress for each case?
� What are the error estimates?
� How many elements did AutoGEM create?
� What are the resultant loads?
7. Click Close > Done when finish.
Note
You have created a single analysis, thermal_mech, and you
selected three Load Sets. Two of these Load Sets need
temperatures from the thermal analysis, thermal_seat, you
defined earlier. Consequently Pro/MECHANICA runs
thermal_seat first and then runs three static analyses, one for
each Load Set. One of these loads, temps, is the stresses due
only to the non-uniform temperature distribution in the seat,
while mech_and_therm is stress due to both the non-uniform
temperature distribution and the 250 lb. person sitting on the
seat. One_side is the stress due to just the person, exactly as onyour first run with the one_cheek load.
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EXERCISE 4: Combining Loads in Results
Note
When you run an analysis, you may toggle on more than one
load in the Load Sets column. Pro/MECHANICA will analyze
and converge the model on one load set at a time. You can ask
for combined loading in the results section; and the software
superimposes the results from each load case. It is important to
note, if you want to converge on combined loading, you should
have both loads defined under one Load Set name.
Task 1. Examine the temperature distribution due to the heat loads from
the sun and the user.
1. Click Results. Click No when prompted to save current model.
2. Create a window to display the temperature distribution.
� Click [Insert result window].
� Enter [temperature ] as the name, followed by Accept.
� Click the thermal_mech\ in the CURRENT DIRECTORY.
� Click Accept to finish.
� In the SELECT ANALYSIS dialog-box, click the
thermal_seat, followed by Accept.
3. Define the result window content
� Select Temperature from the QUANTITY drop down list.
� Select All from the LOCATION drop-down list.
� Select Fringe from the DISPLAY drop down list.
� Clear Animate if necessary.
� Accept other defaults.
� Click Accept and Show.
Task 2. Define and view the convergence graph of the MPA thermal
analysis.
1. Click [Copy window].
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NOTES
2. Enter [flux_gradient ] as the name, followed by Accept.
3. Define the result window content.
� Select Measure from the QUANTITY drop down list to plot a
measure. Click Select.
� Select energy_norm and click Accept.
� Accept other defaults.
� Click Accept and Show.
4. Hide the convergence graph window.
� Click the FLUX_GRADIENT window.
� Click [Hide result window].
5. Hide the temperature result window using the same procedures.
Task 3. Investigate the stresses due to the thermal expansion.
1. Create a result window to display the thermal stress.
� Click [Insert result window].
� Enter [therm_stress ] as the name, followed by Accept.
� Click the thermal_mech\ in the CURRENT DIRECTORY.
� Click Accept to finish.
� In the SELECT ANALYSIS dialog-box, click the thermal_
mech, followed by Accept.
2. Select the load set. In the LOAD SET COMBINATION dialog box,
� Clear the Combine Load Sets if necessary.
� Select temps, followed by Accept.
3. Define the result window content.
� Enter [Seat Thermal Stresses ] for the name.
� Display Total von Mises Stress.
� Display the Fringe plot.
� Select Deformed > Animate and accept other defaults.
� Click Accept and Show.
4. Play the animation and pay attention to the maximum stress and
the location of the stress concentration.
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NOTES
5. Stop the animation when finished.
Task 4. Create a fringe plot of the combined thermal/mechanical stress.
1. Create a new result window.
� Click [Insert result window].
� Enter [combined_loads ] as the name, followed by Accept.
� Click the thermal_mech\ in the CURRENT DIRECTORY.
� Click Accept to finish.
� In the SELECT ANALYSIS dialog-box, click the thermal_
mech, followed by Accept.
2. Select the load set. In the LOAD SET COMBINATION dialog box,
� Clear the Combine Load Sets if necessary.
� Select mech_and_therm, followed by Accept.
3. Define the result window content.
� Enter [Therm/Mech Stress from Combined Loads ] as
the title.
� Display Total von Mises Stress.
� Display the Fringe plot.
� Select Deformed > Animate and accept other defaults.
� Click Accept and Show.
4. Play the animation and pay attention to the maximum stress and
the location of the stress concentration.
5. Stop the animation when finished.
Task 5. Create a von Mises stress fringe plot for the combined
thermal/mechanical loads, but the loads will be combined in the result
section.
1. Create a new result window.
� Click [Insert result window].
� Enter [combined_results ] as the name, followed by
Accept.
� Click the thermal_mech\ in the CURRENT DIRECTORY.
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NOTES
� Click Accept to finish.
� In the SELECT ANALYSIS dialog-box, click the thermal_
mech, followed by Accept.
2. Select the load set. In the LOAD SET COMBINATION dialog box,
� Select the Combine Load Sets if necessary.
� Select one_cheek and temps. Keep the default factors.
Note:
The scale factors can be used to magnify/shrink the effects of
the load sets.
� Clear the mech_and_therm.
� Click Accept.
3. Define the result window content.
� Enter [Therm/Mech Stresses from Combined
Results ] as the title.
� Display Total von Mises Stress.
� Display the Fringe plot.
� Select Deformed > Animate and accept other defaults.
� Click Accept and Show.
4. Reorient the view in multiple windows.
� Select multiple windows using the <Shift>.
� Click View > Spin/Pan/Zoom > Isometric > OK.
5. By comparing the combined result and combined load windows,
we conclude that the maximum stresses and stress distributions in
the two plots are almost identical.
6. Exit the result interface. Click File > Exit Results.
7. Save the result window when prompted for saving the result
windows.
� Choose Yes.
� Enter [SPA], followed by Accept.
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EXERCISE 5: Comparing MPA to SPA
Task 1. Define and run the Multi-Pass analysis.
1. Click Analyses from the MEC STRUCT menu.
2. Make sure Static is selected. Click New.
3. Define the analysis:
� Enter [seat_mpa ] as the name.
� Verify that the Constraint Set ConstraintSet1 is selected.
� Select the Load Set one_cheek.
� Select Multi-Pass Adaptive from METHOD drop-down list.
� Set the Polynomial Order minimum to 1 and the maximum to
9.
� Enter [2] in the PERCENTAGE CONVERGENCE field.
� Select Local Displacement, Local Strain Energy and Global
RMS Stress for the convergence criteria.
� Click Output tab and change the Plotting Grid to 7.
� Click OK > Close.
4. Run the analysis.
� Click Run.
� Select the seat_mpa(Standard/Static) if necessary.
� Click Start to begin the analysis.
5. Monitor the analysis. Click Summary. Notice the following
changes as the analysis run progress.
� Multiple passes are made.
� Each time, the polynomial orders of the equations used in the
solution are increased. Each pass reports fewer “elements not
converged” and more equations than the pass before.
� Eventually, all elements will converge to the specified
percentage and the run will be complete.
Note:
If the analysis does not converge to the specified accuracy,
Pro/MECHANICA will report that, and allow you to look at
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NOTES
the non-converged results. In either case, the overall solution
quality of every run is known and can be controlled by
changing the convergence percentage on the analysis form.
Review the Summary file carefully.
6. Click Close > Done when finish.
Task 2. Define a result window to display a convergence plot and a
fringe plot for the Multi-Pass run.
1. Click Results. Choose No when prompted to save the model.
2. Create a new result window.
� Click [Insert result window].
� Enter [conv_stress ] as the name, followed by Accept.
� Click the seat_mpa\ the CURRENT DIRECTORY.
� Click Accept to finish.
3. Define the result window content.
� Enter [Von Mises Stress vs. P-Pass ] as the title.
� Select Measure from the QUANTITY drop-down list.
� Click Select and select max_stress_vm from the list.
� Click Accept.
� Accept other defaults.
4. Click Accept and Show.
Task 3. Create a fringe plot of von Mises stress for the Multi-Pass run.
1. Click [Copy window].
2. Enter [vm_stress_mpa ] as the name, followed by Accept.
3. Define the result window content.
� Enter [Von Mises Stress Multi-Pass ] as the title.
� For Quantity, select Stress > Total Von Mises.
� Display von Mises Stress.
� Display the Fringe plot.
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� Select Deformed > Animate and accept other defaults.
� Click Accept and Show.
4. Retrieve the previously saved single pass adaptive result windows
for comparison. You will lose the two previously created results,
and you may need to recreate the MPA result.
� Click [Open file].
� Select SPA, followed by Accept.
� Click [Display result windows].
� Select the COMBINED_RESULTS window, followed by OK.
5. A close examination of the result windows shows:
� The Multi-Pass Adaptive analysis converges very well.
� The fringe plots of the Single-Pass Adaptive analysis and
Multi-Pass Adaptive analysis are very close.
6. Exit the result interface. Switch to the standard application. Save
and erase the model.
Note:
The answers with the Multi-Pass Adaptive (MPA) and Single-
Pass Adaptive algorithm (SPA) are within 10% of each other.
For larger models SPA can be up to ten times faster and use up
to two-thirds less disk space than MPA. As a default, you
should use SPA as a solution method. MPA is good for cases
where you would like to specify the convergence, and you
want to manually control the convergence percentage.
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MODULE SUMMARY
You have learned:
• How to define an analysis.
• How to define a combined analysis.
• How to review the results.
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Module
Analysis and Results: ExamplesIn this module, you will apply Pro/MECHANICA modeling
techniques to real-world examples.
Objectives
After completing this module, you will be able to:
• Describe how to build a Pro/MECHANICA model.
• Analyze models for stress and heat distribution.
• Design models around frequency (repetitions per unit time)requirements.
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INTRODUCTION
When you begin applying Pro/MECHANICA, you may select large,
complex models to analyze. However, it is recommended that you initially
attempt to apply Pro/MECHANICA to simple, basic models in order to
learn the process of building and analyzing Pro/MECHANICA models.
Analyzing Models
You must apply the following steps when running Pro/MECHANICA
analyses:
1. Create or import geometry
2. Assign material properties
3. Define loads
4. Apply constraints
5. Create elements
6. Define the analysis
7. Run the analysis
8. Review the results
9. Assign design parameters
10. Run a sensitivity study
11. Run an optimization study
12. Update the part geometry
Steps 1 through 8 define an engineering analysis in order to understand
how a model behaves under certain boundary conditions. Steps 9 through
12 enable you to improve a design.
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LABORATORY PRACTICAL
Goal
• Review the basic steps of building a Pro/MECHANICA model.
• Analyze a roller mill bearing.
• Analyze a pan assembly under heat load and gravity.
• Perform a modal analysis and determine the natural frequency of atuning fork for the musical note "G".
Method
In Exercise 1, you will de-feature a model and then set up and run an
analysis. Understanding the Pro/MECHANICA Structure process will
enable you to expand your skills into more advanced techniques such as
optimization.
In Exercise 2, you will analyze the thermal and structural response of a
Pro/ENGINEER assembly.
In Exercise 3, you will design a tuning fork, run a modal analysis, and
then optimize the model.
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EXERCISE 1: Analyzing Roller Mill BearingMechanical Properties
The model you will be analyzing in this exercise is a mill bearing part.
First, notice that the model contains a large number of features,
specifically, many holes that will increase the size of the
Pro/MECHANICA model. Remember that suppressing features that are
inconsequential to the analysis is recommended practice. Also note that
the model is symmetric and that the boundary conditions are symmetric as
well. Consequently, you will perform two tasks before entering
Pro/MECHANICA:
• Remove features from the part.
• Cut the model in half.
Figure 1: Mill Bearing
Task 1. In Pro/ENGINEER, open the model.
1. Set the working directory to the folder that corresponds to the
name of the current module.
2. Open the MILL_BEARING.PRT.
3. Check that units are mm, Newtons and Seconds.
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Task 2. De-feature the production model to create a simulation model.
The production model is carefully constructed. All the features after Cut
id 2826 can be suppressed.
Note:
There are many pin-holes in your model that will not transmit
any load but will increase the number of elements in the
Pro/MECHANICA model significantly.
Note:
The model is symmetric. It can be cut in half to reduce the
element count. The model is actually constructed in half, and
merged to create the whole model.
1. Display the MODEL TREE if necessary. Click [Toggle model
tree display] to display the MODEL TREE.
2. Click Feature > Suppress > Clip.
3. Click the first Pattern(Hole).
4. Click Done.
Task 3. Enter Pro/MECHANICA Structure and apply material
properties.
1. Enter Pro/MECHANICA. Click Applications > Mechanica >
Continue > Structure.
2. Apply steel material properties to the part.
� Click Model > Materials. The MATERIALS dialog box
appears.
� Select STEEL from MATERIALS IN LIBRARY and add to
MATERIALS IN MODEL.
� Click Assign > Part, then click the part. Click Done Sel >
Close.
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Task 4. Create two loads that belong to the same load set.
1. Create a bearing load of 1,000,000 Newtons applied to the large
inner cylindrical surface in the positive Y-direction.
� Click [Create a bearing load].
� Click [Select] under the HOLE(S).
� Click the surface as shown in the following figure, then click
Done/Sel.
Figure 2: Bearing Load Surface
� Enter [1000000 ] fort the Y component
� Click Preview. The message displayed is a warning that
Pro/MECHANICA was expecting an entire cylindrical surface
for the bearing load. Click OK since this model has been cut at
the plane of symmetry.
� Click OK > OK.
2. Create a surface load of 500,000 Newtons in the positive Z-
direction applied to the lip of the inner protrusion
� Click [Create a surface load].
� Click [Select] under the SURFACE(S).
� Use Query Sel to select the surface as shown in the following
figure.
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NOTES
Figure 3: Surface Load in the Z-direction
� Click Done Sel.
� Enter [500000 ] for the Z-direction.
� Click Preview > OK. The model should appear as shown in the
following figure.
Figure 4: Finished Loads
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Task 5. Create three constraints that belong to the same constraint set.
1. Create a sliding constraint on the pin hole surfaces.
Note:
A sliding constraint allows a constrained surface to slide in its
own plane but not perpendicular to it. Therefore, the
translation normal to the plane is fixed.
� Click [Create a surface constraint].
� Click [Select] under the SURFACE(S).
� Select the bottom flat surface of all three pin holes, followed by
Done/Sel.
� Fix the Y-direction translation and free the other DOFs. Click
OK when finished.
2. Create another sliding constraint.
� Click [Create a surface constraint].
� Click [Select] under the SURFACE(S).
� Select the flat surface as shown in the following figure.
Figure 5: Second Sliding Constraint
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� Fix the Z-direction translation and free the other DOFs. Click
OK when finished.
3. Create a symmetric constraint.
� Click [Create a surface constraint].
� Click [Select] under the SURFACE(S).
� Select the plane of symmetry.
� Fix the X-direction translation and the Y and Z-direction
rotation. Free the other DOFs. Click OK when finish.
Task 6. Define and run the analysis.
1. Create a static SPA analysis named mill_static . Accept the
other default options when defining the analysis.
2. Run the analysis and monitor the process.
3. Review the summary file. Note the following information.
� Total Elapsed Time ________________
� Total CPU Time _______________
� Solution "efficiency", CPU Time divided by Total Elapsed
Time ______________%.
� Working Directory Disk Usage _________________ Mb.
� Result Directory Size ___________________ Mb.
� Maximum Memory Usage ___________________ Mb.
� How many elements are in the model? __________________
� What is the error of the solution? ______________ %.
� Measure: max_disp_mag __________________
� Measure: max_stress_vm __________________
4. Click Close > Done when finish.
Task 7. View and interpret the results.
1. Create two result windows:
� Repeated displacement animation (for the display, select
animation instead of fringe).
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� Repeated von Mises stress animation fringe plot over the entire
model.
2. The result windows should appear as shown in the following
figure.
3. Switch to the appropriate orientations to visually verify the effects
of the boundary conditions.
Figure 6: Displacement and Stress Results
4. In the stress results window, notice the "hot" spots (in red) near the
symmetric boundary.
5. Also notice the few "green" spots near the sliding constraints.
Constraints can often introduce artificially high stresses at the
constraint boundary. These high stresses can typically be
disregarded.
Task 8. Focus on the "hot" spots(von Mises stress higher than 100
MPa).
1. In the stress window, change the fringe legend so that any stress
above 100 MPa (N/mm2) is indicated in red.
� Click Edit > Legend Value.
Note:
If the yield stress of steel is 200 MPa and you want to maintain
a safety factor of 2, no stress in the model should exceed 100
MPa.
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� Click the first value beneath the Maximum stress.
� Enter [100 ], followed by OK.
2. Exit the result interface. Switch to the standard application. Save
and erase the model.
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NOTES
EXERCISE 2: Analyzing Frying Pan ThermalProperties
In this exercise, you will use Pro/MECHANICA to ensure that a frying
pan distributes heat evenly and is structurally strong.
The model consists of two simple parts—the pan itself and the handle. The
bolts have been removed to simplify the assembly.
Figure 7: Frying Pan
You will perform two types of analysis:
• A thermal analysis will simulate the pan sitting on a hot stove.
• A static analysis will determine if the handle is strong enough towithstand the weight of the pan.
Task 1. Retrieve the pan. Create the datum curves for region creation.
The region is used to represent the ring of heat from a gas stove.
1. Open PAN.PRT. Make sure that unit system is millimeter Newton
Seconds(mmNs).
2. Create circular datum curves on the bottom of the pan.
� Click [Insert a sketched curve].
� Select the bottom surface of the pan.
� Sketch a 177.8 mm diameter circle concentric to the pan.
� Click [Done] to finish.
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3. Create another circular datum curve with a 127 mm diameter using
the same procedures. The model should appear as shown in the
following figure.
Figure 8: Bottom of The Pan With Two Datum Curves
Note:
The datum curves will be used for regions and must be applied
to the part, not to the assembly. In addition, the curves must becreated as separate features or the region creation will fail.
Task 2. Create two surface regions in Pro/MECHANICA.
1. Enter Pro/MECHANICA. Click Applications > Mechanica >
Continue > Structure.
2. Split the bottom surface into two surface regions.
� Click Model > Features > Surf Region > Create > Select >
Done.
� Select the outer datum curve, when prompted.
� Select the bottom surface of the pan, when prompted.
� Click Done Sel > Done > OK. The bottom surface is split into
two surfaces.
3. Split the surface again using the other curve.
� Click Create > Select > Done.
� Select the inner curve.
� Select the bottom, inner surface of the pan.
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� Click Done Sel > Done > OK. The bottom, inner surface is
split into two surfaces (for a total of 3 surfaces on the bottom
of the pan).
4. Click Done/Return twice.
5. Switch to the standard application. Save and close the window.
Task 3. Retrieve the handle. Create the datum curves for region
creation. The region will represent the area held by hand.
1. Open PAN_HANDLE.PRT. Make sure that unit system is
millimeter Newton Seconds(mmNs).
2. Create a datum plane offset from the end of the handle 116 mm
towards the pan.
� Click [Create a datum plane].
� Select Offset. Select the end surface of the handle.
� Select Enter Value. Enter [-116 ], followed by Done.
3. Create datum curves.
� Click [Create datum curve].
� Select Intr.Surfs > Done > Whole.
� Select the top surface of handle.
� Select Single and select DTM4 that was just created.
4. The model should appear as shown in the following figure.
Figure 9: Datum Curve Created On The Handle
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Task 4. Enter Pro/MECHANICA and create a region on each of the four
sides of the handle.
1. Enter Pro/MECHANICA. Click Applications > Mechanica >
Continue > Structure.
2. Split the top handle surface into two surface regions.
� Click Model > Features > Surf Region > Create > Select >
Done.
� Select the datum curve, when prompted.
� Select the top, bottom, and side surfaces of the handle, when
prompted.
� Click Done Sel > Done > OK. The four surfaces are each split
into two surfaces, for a total of eight surfaces.
3. Verify that four regions have been created. Click Show All. Do
not worry about which surfaces highlight. What is important is
that there are now separate surfaces on which loads or constraints
may be applied.
4. Click Done/Return.
5. Switch to the standard application. Save and close the window.
Task 5. Open the frying pan assembly model. Create a datum curve on
the pan where it intersects with the handle. The datum curve will be used
for surface region creation.
1. Open the FRYING_PAN.ASM. Make sure that unit system is
millimeter Newton Seconds (mmNs).
2. Click [Select primary item].
3. Right-click the pan from the Model Tree and choose Insert
Feature.
4. Click [Create datum curve].
5. Select Composite > Done > Exact > Done.
6. Click the four edges of the handle part that are in contact with the
pan.
7. Click Done > OK to finish.
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Task 6. Create a surface region where the handle intersects the pan.
1. Enter Pro/MECHANICA. Click Applications > Mechanica >
Continue > Thermal.
2. Click Model > Features > Surf Region > Create.
3. Select the pan, when prompted for component.
4. Choose Select > Done.
5. Select the rectangular datum curve, when prompted for curves.
6. Select the outer surface of the pan that intersects the handle, when
prompted.
7. Click Done Sel > Done > OK > Done/Return.
Task 7. Assign the material properties.
1. Apply material properties. Click Model > Materials.
� Assign the pan AL6061
� Assign the handle STEEL.
Note:
Aluminum has more than 4 times the thermal conductivity of
steel, making a good material for cooking. On the other hand,
steel has lower thermal conductivity, making it a good
candidate for the handle because of the high thermal
resistance.
Task 8. Simulate the cooking heat with the appropriate boundary
conditions.
1. Simulate the cooking heat from the gas stove (12,500 BTU/hr)
with a heat load.
� Click Model > Heat Loads > New > Surface.
� Enter [cooking_heat ] as the name.
� Click [Select] and select the ring shape surface region.
Click Done Sel.
� Select Total Load from the DISTRIBUTION drop-down list.
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� Enter [3661000 ].
Note:
The value is calculated by converting 12,500 BTU/hr into N
mm/sec.
N mm/sec is the unit for heat flux in the mmNsec unit system.
� Click OK > Done/Return to finish.
2. Simulate the heat loss due to ambience air with a convection
boundary condition.
� Click Model > Bndry Conds > New > Conv Cond > Surface.
� Enter [cool_air ] as the name.
� Click [Select] and select the following surfaces:
• The narrow top surface.
• Internal and external surfaces of the round.
• Internal and external surfaces of side.
Note:
When selecting the external side surfaces. The rectangular
region where the pan intersects the handle is excluded.
� Click Done Sel.
� Enter [0.4 ] for CONVECTION COEFFICIENT.
� Enter [25] for BULK TEMPERATURE.
� Click OK to finish.
3. Simulate the heat loss due on the cooking surface with a
convection boundary condition.
� Click New > Conv Cond > Surface.
� Enter [cooked_food ] as the name.
� Click [Select] and select the interior bottom surface where
the food is cooked.
� Click Done Sel.
� Enter [0.5 ] for CONVECTION COEFFICIENT.
� Enter [100 ] for BULK TEMPERATURE.
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� Click OK to finish.
4. Simulate the heat loss through the handle surfaces not held by the
cook's hand with a convection boundary condition.
� Click New > Conv Cond > Surface.
� Enter [handle_heat_loss ] as the name.
� Click [Select] and select the handle surfaces that are not
touched by hand.
� Click Done Sel.
� Enter [0.35 ] for CONVECTION COEFFICIENT.
� Enter [25] for BULK TEMPERATURE.
� Click OK > Done/Return to finish.
Task 9. Create a steady-state thermal analysis.
1. Click Analyses. Accept the default Steady Thermal analysis type.
2. Click New. Enter [pan_therm ] as the name.
3. Make sure you select the correct constraint and load sets and
accept all other default options.
4. Click OK > Close > Done/Return when finish.
Task 10. Simulate the structural aspect of the pan model. The materials
have already been defined in the previous tasks. Define the constraint
(where the cook is holding the handle) and the load (gravity).
1. Enter Pro/MECHANICA Structure. Click Structure.
2. Define a surface constraint that simulates the holding hand.
� Click [Create a surface constraint].
� Click [Select] under the SURFACE(S).
� Select the four surface regions held by hand.
� Fix X, Y and Z-direction translations and free the other DOFs.
� Click OK when finish.
3. Define a gravity load.
� Click [Insert a gravity load].
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NOTES
� Enter [-9810 ] for Z.
� Preview and click OK to finish.
Task 11. Create a static structural analysis.
1. Click Analyses. Accept the default Static analysis type.
2. Click New. Enter [pan_static ] as the name.
3. Make sure you select the correct constraint and load sets and
accept all other default options.
4. Click OK > Close when finish.
Task 12. Create a design study that includes the structural and thermal
analyses.
1. Click DesignStudies.
2. Enter [pan_study ] as the name.
3. Select both the pan_therm and the pan_static .
4. Click Accept > Done to finish.
Task 13. Run the analysis and monitor the process using the summary
file. Note the following information when the analysis is finished.
1. Total Elapsed Time ________________
2. Total CPU Time _______________
3. Working Directory Disk Usage ___________________ Mb
4. Result Directory Size ___________________ Mb
5. Maximum Memory Usage ___________________ Mb
6. How many elements are in the model? __________________
7. What is the error of the solution? ______________ %
8. What is the maximum displacement magnitude? __________mm
9. What is the maximum Von Mises stress? ____________ N/mm2
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10. What is the maximum temperature? ____________ oC
Task 14. Create result windows to display the results.
1. Create an animated result window to view the displacement. Use
"animation" as the display instead of fringe.
2. Create an animated fringe plot to display von Mises stress.
� As expected, high stresses occur at the junction between the
handle and the mounting plate. However, since these stress
values are much lower than the material's yield strength, these
stresses are not a big concern.
3. Create a result window to display temperature distribution.
� Notice that the temperature is evenly distributed around the
thick aluminum bottom.
4. Exit the Results window. Save and erase the model.
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NOTES
EXERCISE 3: Analyzing a Tuning Fork
Tuning forks produce a sound by vibrating at specific resonant
frequencies. If the resonant frequency is within the audible range of 20 Hz
to 20,000 Hz, then the frequency can be classified as a musical note. For
example, the note, middle-C, a vibrates at 256 Hz, whereas the note, E,
vibrates at a frequency of 320 Hz. Piano tuners and guitar players use
tuning forks to tune their instruments to certain musical notes.
In this exercise, you tune a fork to the musical note "G", which vibrates at
384 Hz.
Task 1. Build the simulation model.
1. Open the part FORK.PRT. Make sure the units are in mm,
Newtons, and seconds.
2. Enter Pro/MECHANICA Structure and apply steel material
properties to the tuning fork part.
3. Fully constrain the handle surface of the fork (the cylindrical
protrusion).
Task 2. Run the modal analysis.
1. Click Analyses > Modal (from the drop down list) > New.
2. Enter [fork_mode ] for the analysis name. Change the number of
modes to [1], because we are interested in the lowest, or primary
mode.
3. Accept all other defaults.
4. Run the analysis.
Task 3. Verify the accuracy of the model and note the following:
1. Total Elapsed Time ________________
2. Total CPU Time _______________
3. Working Directory Disk Usage ________________ Mb
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4. Result Directory Size ___________________ Mb
5. Maximum Memory Usage ___________________ Mb
6. How many elements are in the model? __________________
7. What is the error of your solution? ______________ %
Task 4. Now that you understand the resources the analysis required and
the error it produced, you are ready to start reviewing the results. In the
summary file, you may find the calculated modal frequency.
1. What is the modal frequency? _________________ Hz. You have
determined that this frequency is approximately G# (G-sharp)
which is close, but half a note from your desired frequency of G.
2. Create a displacement animation result window.
Task 5. Define a design parameter. The length of the tuning fork will
dictate its resonant frequency. .
1. Assign a design parameter to the length of the fork. Click Model >
Dsgn Controls > Design Params.
2. Click Create > Dimension > Select. Pick the fork feature. Pick
the 91.24mm dimension as shown in the following figure. Enter
[Fork_length ] as the new name for design parameter.
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NOTES
Figure 10: Design Parameter On The Tuning Fork Length
3. Define the range from a minimum of 90 to a maximum of 110.
4. Click Accept > Done.
Task 6. Optimize the model. To achieve the desired note of G, the
resonant frequency must be 384 Hz. This will be accomplished by varying
the length of the fork.
1. In Pro/MECHANICA Structure, define an optimization. Click
DesignStudies.
2. For the optimization name, enter [fork_opt ].
3. Select Optimization from the TYPE drop-down list.
4. Clear the Goal check box.
5. Define the Limits on Measures.
� Click Create
� Select modal frequency from the pre-defined measure list
� Click Accept.
� Set modal_frequency equal to [384 ].
6. Select the Fork_length parameter in the parameters section.
7. Accept all other defaults.
8. Run the optimization.
Task 7. Verify the results of the optimization.
1. Enter the total Elapsed time. ____________________ sec
2. What is the final value of design parameter? ____________ mm
3. What is the optimized modal frequency? _______________ Hz
4. Is this within the 1% specified in the optimization convergence?
________________
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Task 8. Update the model using the optimized design parameter.
1. Click Model > Dsgn Controls > Optimize Hist > Enter Study.
Enter [fork_opt ] when prompted and answer Y to all questions.
2. When you have completed this process, the fork will be tuned to G.
3. Create a plot of the modal frequency vs. optimization pass. It
should look like the following figure.
Figure 11: Modal Frequency vs. Optimization Pass
4. Exit the result interface. Switch to the standard application. Save
and erase the model.
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MODULE SUMMARY
You have learned how to:
• Set up and run a Pro/MECHANICA structural analysis.
• Set up and run a thermal analysis and a structural analysis,simultaneously.
• Set up and run a modal analysis and an optimization design study.
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Page 9-1
Module
Running Sensitivity and Optimization StudiesSo far, you have learned how to model and analyze a part in
Pro/MECHANICA. In this lesson, you will learn the tools that
enable you to determine how sensitive measures such as stress,
displacement, and mass are to changes in model parameters. You
will also learn how to optimize your model by setting goals and limits
on measures, while varying model parameters.
Objectives
After completing this module, you will be able to:
• Set up and run design and optimization studies.
• Describe the purpose of design parameters.
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INTRODUCTION
Sensitivity studies enable you to more fully understand the effects of
varying the design parameters on your model. You can use these studies to
determine how sensitive a particular quantity, such as von Mises stress, is
to variations of a particular dimension parameter. Pro/MECHANICA
provides the following sensitivity capabilities:
Running Global Sensitivity Studies
Global sensitivity studies are used to generate a picture of how measures
respond to changing a design parameter over a specified range (usually a
large range, hence the name global). Global sensitivity studies provide the
big picture and will be most useful in understanding the overall effect of a
given parameter.
Running a global sensitivity study helps you understand in detail how
changes are affecting your part. You will then use this information to set
up the optimization study.
Normally you would run global sensitivity studies on all the parameters
that survived the local sensitivity study, but in the interest of time, you
will run global sensitivity studies for limited parameters.
In the exercise, you will run a global sensitivity on the slot length
parameter to get a better understanding of its impact on your model.
However, by doing so, you can only determine the optimal value for a
given parameter if it were varied alone. But would this optimal parameter
value be the same if other design parameters were changed
simultaneously? The answer is most likely no. This is why you need the
optimizer. However, this does give you a good starting position for the
optimizer.
Running Local Sensitivity Studies
Local Sensitivity Studies are used to calculate the sensitivity of your
model's measures to perturbations (very slight changes) in parameters.
Pro/MECHANICA uses local sensitivity to perturb a dimension parameter
by 1% to estimate the derivative of your measure with respect to the
parameter. Thus, for a given location in parameter space, you may take a
"snapshot" of the sensitivity of your model subject to all parameters. If
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NOTES
parameter A induces a slope of your measure of 100, while parameter B
induces a slope of your measure of 0.01, then you may postulate that
changing the parameter A will have a bigger effect than working with
parameter B. Therefore, you use local sensitivity to narrow your selection
of dimension parameters to the most important ones.
Running Optimizations
An optimization study adjusts one or more parameters to best achieve a
specified goal or to test feasibility of a design, while respecting specified
limits.
To create an optimization study, you define the following components:
Goal – You select a measure to minimize or maximize as the study's goal.
Limits – You define limits on one or more measures that
Pro/MECHANICA cannot violate during the optimization.
Parameters – You select one or more design parameters you want
Pro/MECHANICA to adjust to achieve the goal. You will also define a
range and initial value for each parameter.
The goal and limits are each optional, but you must have at least one goal
or one limit.
Pro/MECHANICA adjusts the model's parameters in a series of iterations
through which it tries to move closer to the goal while satisfying any
limits. If you have no goal, Pro/MECHANICA simply tries to satisfy your
limits. An optimization with no goal is sometimes called a feasibility
study. If you do not define a goal, you must define limits. Without a goal,
Pro/MECHANICA searches for the first feasible design that satisfies the
limits you define.
When defining a goal and limits, you can select measures associated with
different analysis types. You can set up an optimization that would
perform any of Pro/MECHANICA's analysis types except motion and
contact. For example, you could optimize the clip for stress, displacement,
natural frequencies (modes), and temperature simultaneously.
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LABORATORY PRACTICAL
Goal
To use sensitivity and optimization design studies to view the effects of
design variables and find an optimized model.
Method
In the first exercise you will create a Pro/MECHANICA model and define
design parameters.
In the second exercise, you will run a sensitivity study to view the effects
of varying the design parameters on specific aspects of your model.
In the third exercise, you will run an optimization study to find an
optimized set of dimensions for your model. The goal is to reduce the
stress in this model while increasing the maximum deflection to a value
greater than 7 mm, but less than 9 mm. You will also attempt to reduce the
weight of the current design.
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NOTES
EXERCISE 1: Optimizing a Belt Clip
The belt clip model you will be optimizing, as shown in the following
figure, fits onto a portable electronic device. The part is inserted and
released from its latch by applying a 2.5 N force downward on the tab.
The catch that protrudes down from the curved tip moves up and must
clear a latch that is 7 mm high, but the maximum deflection cannot exceed
9 mm. In addition, the stresses must be kept to a minimum without
increasing the weight of the part.
Catch
7 mm <displacement < 9 mm
Press down the
tab with 2.5 N
Constrain the
Flange
Clip Body
Curved Tip
Figure 1 The Clip Part
Task 1. Build the simulation model by cutting away half of the
symmetric model.
1. Set your working directory to the folder that corresponds to the
name of the current module.
2. Open the part CLIP.PRT. Check that units are mm, Newtons and
Seconds.
3. Cut away half of the part. Click Insert > Cut > Extrude. Click
Both Sides > Done.
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4. Select DTM2 as the Sketching Plane and click Default as
orientation reference. Create a sketch to remove the left half of the
clip and complete the feature. When finished the clip should look
like the following figure.
Figure 2 The Symmetric Clip Cut in Half
Task 2. Create a datum point for the measure. One of your big concerns
is, for the given load, will the catch displace enough to clear the latch on
the mating part? You will now add a measure to track the displacement of
a point on the tip of the catch, but first you need to create the datum point
at the point of interest.
1. Create a datum point as shown in the following figure.
� Click [Insert a datum point].
� Select On Vertex.
� Click the vertex of the catch to create the point, as shown in the
following figure.
� Click Done Sel > Done when finish.
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Figure 3 Create a datum point at the tip of the catch.
Task 3. Create a Region in Pro/MECHANICA to apply the load. The
load on the tab will be applied by a finger pressing on a localized area
represented by a region.
1. Enter MECHANICA. Click Applications > Mechanica >
Continue > Structure.
2. Create surface region for load. Click Model > Features > Surf
Region > Create > Sketch > Done.
3. Sketch the section of the region.
� Select the top surface of the tab as the sketching plane.
� Select Bottom and select DTM3 as the reference plane.
� Specify the appropriate sketching references and draw a
horizontal line across the tab as shown in the following figure.
� Dimension the curve 6.35 from the edge of the tab.
� Click [Done] to finish.
4. Select the top surface of the clip, where the sketch resides on, to
split. Click Done Sel > Done > OK.
5. Verify the created region.
� Click View > Model Setup > Mesh Surface.
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� Click the region. The region should appear as shown in the
following figure.
Figure 4 Create the Region
Task 4. Create the midsurfaces.
1. Click Done/Return.
2. To create the surface pairs, click Idealizations > Shells >
Midsurfaces > Auto Detect.
3. Test the compression to verify a successful pairing. Click
Compress > Shells only > ShowCompress. The midsurfaces
model should look like the following figure.
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NOTES
Figure 5 The Midsurface Clip
Task 5. Set the material properties.
1. Assign NYLON material properties to the clip.
2. Edit the NYLON properties to assign values for failure criteria.
� Click the Failure Criterion tab in the MATERIAL DEFINITION
dialog box.
� Select the Distortion Energy (von Mises) option from the
drop-down list. Enter [85] for the TENSILE YIELD STRESS.
Note:
The tensile yield strength entered does not affect the
calculations that Mechanica makes during the analysis. The
purpose of this value is to provide a more convenient option
for plotting stress results.
� Select [N/mm^2] for the units of the tensile yield strength.
Task 6. Define the constraints.
1. Apply a symmetry constraint to the model.
� Select the 5 edges shown in the following figure.
� Constraint the X translational dof, Y and Z rotational dof on
the plane of symmetry. Free other dofs.
2. Create a second constraint. The clip is glued to the appliance at the
flange location. Fix all dofs of the bottom surface of the flange,
shown in the following figure.
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Constraint these edges
Constraint this surface
Figure 6 Constrain the clip.
Task 7. Define a surface load to simulate a finger pushing on the tab.
1. Apply a 1.25 N surface load (half of the total load, due to the
symmetry), in the negative Y-direction on the created region. After
the load is applied, the model should appear as shown in the
following figure.
Figure 7 Apply a surface load.
Task 8. Define the measures. Because the tip of the catch must clear a 7
mm latch, you will want to track the displacement at the bottom of the
catch with a measure.
1. Define the measures. Click Model > Measures.
2. Pro/MECHANICA informs you of the coordinate system that the
measure will reference. Click OK.
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NOTES
3. Enter [Y_disp_clip_tip ] for the measure name.
4. Select Displacement for QUANTITY.
5. Click Select/Review and select PNT0.
6. Accept other defaults and close the dialog boxes.
Task 9. Create and run a static analysis.
1. Create a static analysis called CLIP_STATIC.
� Click Analyses from the STRC MODEL menu.
� Leave Static as the TYPE and click New.
� Enter [clip_static ] as the name. Accept all the defaults and
click OK> Close.
2. Click Done/Return > Settings and verify that Use Pairs is
selected.
3. Run the structure analysis.
Task 10. Checking the results.
1. Examine the summary file and the key statistics regarding the
model, such as the number of elements, the elapsed time, and
required disk resources.
2. Look for maximum von Mises and principal stresses, maximum
displacement, resultant loads, and error estimates.
� Did the run complete without any errors? ________
� What is the value for Y_disp_clip_tip? ___________mm
Task 11. Display and interpret the results.
1. Create an animated result window to display the displacement
fringe plot.
2. Create an animated result window to display the von Mises Stress
fringe plot. Notice that the high stress area is near the inner tab
fillet area.
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Task 12. Create a Failure Criteria results window.
1. Create a failure index result window by copying the stress window.
� Enter [failure_index ] as the name.
� Select Failure Index as the QUANTITY.
� Unselect Animate.
� Accept other defaults.
2. The results indicate that the failure index is below 1.0 for the entire
model. This means there are no areas in the model where the
stresses will surpass yield stress of the material.
3. (Optional) Set the color legend to display the area that is above 1
in red. The model should have no red spot.
4. Exit the result window interface.
Task 13. Define design parameters. Design Parameters change the shape
of the model within a specified range during a sensitivity or optimization
design study.
1. Create the Design Parameters. Click Model > Dsgn Controls >
Design Params > Create. The DESIGN PARAMETER
DEFINITION dialog box appears.
2. Select the design parameter.
� Leave the TYPE as Dimension and click Select.
� Select the slot feature. Use Query Sel if necessary.
� The dimensions associated with the slot feature will then
appear. Select the R0.89 dimension. This dimension controls
the width of the slot.
3. Change the name to [slot_radius ].
4. Enter [0.8 ] for the minimum and [1.5 ] for the maximum. Click
Accept to complete the design parameter definition.
5. Repeat this process to create the design parameters shown in the
following table.
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NOTES
Table 1: Design Parameters
Dimension Minimum Maximum
slot_length, d32 (orig=31.75) 19.05 44.45
slot_width, d50 (orig=7.62) 2.54 7.62
body_width, d51 (orig=20.32) 17.78 25.4
Task 14. Shape Animate the clip.
Note:
Use Shape Animate to vary the parameters across different
ranges and in different combinations, to anticipate problems
that might arise during the optimization process, and to make
sure the parameter ranges are causing the part to change as
intended.
Also, use Shape Review to review the model at specific
settings for each parameter and to identify conflicting design
changes within dimension ranges.
1. Click Shape Animate.
2. Select on all four of the design parameters, and set the NUMBER
OF INTERVALS to 2. Click Animate. When prompted, press
<Return> to continue.
3. The clip is regenerated at the initial and final configuration shown
in the following figure.
Figure 8 Shape Animation
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NOTES
4. When prompted to restore the model to its original shape, click
Yes.
Task 15. Shape Review the clip. Shape Review modifies the current
value of any or all of the design variables.
1. Click Shape Review.
2. Select all of the design parameters and click Review.
3. When prompted to restore the model to its original shape, click
Yes.
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NOTES
EXERCISE 2: Running Sensitivity Studies
Task 1. Create a local sensitivity.
1. Click DesignStudies from the MEC STRUCT menu.
2. In the DESIGN STUDY DEFINITION dialog-box, enter [clip_ls ]
for the study name.
3. Select Local Sensitivity from the TYPE drop down list.
4. Verify that clip_static is selected.
5. Click Set Parameters and select all parameters by checking all
the check boxes next to the parameters.
6. Set the parameter values as shown in the following figure.
Figure 9 Define a Local Sensitivity Design Study.
7. Accept all the defaults. Click Accept > Done to finish.
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Task 2. Run the design study.
1. Click Run. Click Settings in the RUN dialog box.
2. Reuse elements from an existing study.
� Select “Use elements from an existing study” and click
Select.
� Select clip_static, followed by Accept > Accept.
3. Click Start. Use the summary file to monitor the process.
4. Pay attention to the run times, convergence behavior, and
information dealing specifically with local sensitivity.
Task 3. Review local sensitivity results. Create four result windows to
compare how much of an effect each of the four parameters is having on
maximum von Mises Stress.
1. Click Results from the MEC STRUCT menu.
2. In the result interface, click [Insert a result window].
3. Name the window [slot_rad_stress ].
4. Select the clip_ls results directory, and click Accept.
5. For the MEASURE select max_stress_vm, followed by Accept.
6. For the DESIGN VAR, select slot_radius, followed by Accept.
7. Clip Accept and Show the result window definition.
8. Copy the result window to create and display three more windows.
� The names are [slot_wide_stress ], [slot_len_stress ]
and [body_wide_stress ].
� Keep the max_stress_vm as the MEASURE.
� Select slot_width, slot_length, and body_width as the
DESIGN VAR respectively. Display all four windows.
9. By default, the four windows will all have different Y-axis scales.
To compare the four parameters, you will tie the graphs together.
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� Click the SLOT_LEN_STRESS window that has the largest Y-
axis scale.
� Click Utilities > Tie > Graphic Quantity and select another
window.
� Repeat for the other two windows. When finished, all graphs
should have the same Y-axis range.
Note:
The von Mises stress should always be non-negative.
The local sensitivity plot extrapolates the von Mises stress
over a parameter range, using the sensitivity at a specific
parameter value. Therefore, the graphs may indicate
“negative” von Mises stress.
Task 4. Create four windows to see the effect of the parameters on the
displacement measure Y_DISP_CLIP_TIP.
1. Copy the body_wide_stress window to [body_wide_y_disp ].
2. Change the MEASURE from max_stress_vm to Y_disp_clip_tip.
3. Blank all the von Mises stress windows.
4. Create and show other three windows by copying the
body_wide_y_disp window. Use the following result window
names, measures and design parameters:
� slot_wide_y_disp: Y_disp_clip_tip vs. slot_width
� slot_len_y_disp: Y_disp_clip_tip vs. slot_length
� slot_rad_y_disp: Y_disp_clip_tip vs. slot_radius
5. Tie all the Y-axes together.
6. Review the plots and determine the following information.
� Which parameter has the greatest effect on the tip's
displacement? _______________________
� Which parameter has the least, or perhaps no effect?
______________________
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7. The following observations can be made:
� The tip displacement is most sensitive to slot length and slot
width.
� Slot radius appears to have less effect.
� Body width has no effect at all.
8. The following conclusions are made:
� The slot length and slot width have a big impact on the
maximum von Mises stress and clip tip displacement.
� Slot radius has less effect.
� Body width has no effect on the maximum von Mises stress
and clip tip displacement.
� Since body width has no effect on any quantity of interest, it
will be excluded from future studies.
Note:
The calculated slopes are strictly relevant to the single
geometry state called for in the Local Sensitivity Study
definition form. The slopes will be different for differentcurrent values of your parameters.
9. Exit result interface when finished.
Task 5. Define and run a global sensitivity design study called CLIP_GS
to study the effect of slot_length over its range.
1. Click DesignStudies > Create.
2. Enter [clip_gs ] for the design study name. Select Global
Sensitivity for the TYPE.
3. Verify that clip_static is selected.
4. Select slot_length and unselect all other parameters.
5. Change the NUMBER OF INTERVALS to 4.
6. Verify that Repeat P-Loop Convergence is selected. The dialogbox should appear as shown in the following figure.
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NOTES
7. Click Accept > Done to finish.
Figure 10 Define a global sensitivity.
8. Run the global sensitivity study clip_gs. Monitor the process using
the SUMMARY file.
Task 6. Review the global sensitivity results. Look at sensitivity plots of
mass, von Mises Stress, and tip displacement versus the slot length
parameter.
1. Create a results window:
� Name the window [slot_len_mass ], referencing the clip_gs
design study.
� Select clip_static analysis.
� Select total_mass for the MEASURE and slot_length for the
DESIGN VAR.
2. Create and show three more windows by copying the
slot_len_mass window. Use the same DESIGN VAR slot_length.
� Name: slot_len_vm; MEASURE: max_stress_vm
� Name: slot_len_disp; MEASURE: Y_disp_clip_tip
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Page 9-20 Fundamenta ls o f Pro /MECHANICA
NOTES
� Name: slot_len_maxd; MEASURE: max_disp_mag
3. The following observations can be made from the result windows:
� Increasing the slot length decreases mass.
� Increasing the slot length also increases maximum
displacement and the clip tip deflection
� Increasing the slot length increases the maximum stress.
4. The observations above will help us prepare the optimization,
where our goal is to find the value for the slot_length that
decreases stress, and mass, and results in a clip tip deflection
between 7 mm and 9 mm.
5. Exit result interface when finished.
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Running Sens i t i v i ty and Opt imizat ion Studies Page 9-21
NOTES
EXERCISE 3: Optimizing the Clip
Task 1. Define an optimization.
1. Click DesignStudies from the MEC STRUCT menu.
2. Click Create and enter [clip_opt ] as the name.
3. Select Optimimization for the TYPE.
4. Define the GOAL: Minimize max_stress_vm.
5. Define the LIMITS: Y_disp_clip_tip > 7, Y_disp_clip_tip < 9,
and total_mass < 2.2e-6.
Note:
When the unit system is mmNsec, the mass unit is a metric
tonne.
6. Define the parameters that will be used in the optimization. Check
the check boxes next to the slot_radius, slot_length and
slot_width parameters.
7. Since the parameter body_width does not impact stress or
displacement as seen in the local sensitivity analysis, make sure the
check box is CLEARED. You may have to scroll through the
parameter list.
8. Define the parameter initial values. Set all parameters (except
body_width) to the middle numeric value.
9. Converge to 2% with a max number of iterations of 20. Verify that
Repeat P-Loop Convergence is selected.
10. The dialog box should look like the following figure. Click Accept
> Done when finish.
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Page 9-22 Fundamenta ls o f Pro /MECHANICA
NOTES
Figure 11 Optimization Study Definition
Task 2. (Optional)Run the optimization.
1. Run the optimization. Monitor the process using the summary file.
2. Alternatively, you can retrieve the provided result to save time.
Task 3. Create four result windows showing the optimization history of
displacement, tip displacement, von Mises stress and mass.
1. If you have run the optimization, use those results to create result
windows. Otherwise, use the results provided to create result
windows. Consult the instructor for the “stored results” location, if
necessary.
2. Create the following result windows to display the measure
variation vs. Iteration during the optimization.
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Running Sens i t i v i ty and Opt imizat ion Studies Page 9-23
NOTES
� NAME [vm_opt_pass ]; MEASURE: max_stress_vm
� NAME [disp_opt_pass ]; MEASURE: Y_disp_clip_tip
� NAME [mass_opt_pass ]; MEASURE: total_mass
� NAME [maxd_opt_pass ]; MEASURE: max_disp_mag
3. Examine the windows.
� The results show the measure variation during the
optimization. Notice the maximum von Mises stress changes
from 66 M Pa to approximately 50 M Pa.
� The optimized model satisfies all constraints.
� As Pro/MECHANICA approaches the optimal shape, the
values for stress, displacement, and mass stop fluctuating; and,
as soon as all of the values are within 2% of the goal and
limits, the optimization is complete.
Task 4. Create result windows for von Mises and displacement stress
fringe animations.
1. Create von Mises stress fringes without animation.
2. Click Info > Model Max to display the maximum von Mises stress
on the model.
3. Create an animated displacement result window. Review the
results window carefully.
4. Exit the result interface when finished.
Task 5. Update the current part design dimensions to those of the
optimized design.
1. Click Model > Dsgn Controls > Optimize Hist > Search Study.
2. Select clip_opt from the list. Pro/MECHANICA begins an
animation of the shape changes.
3. Click <Return> when prompted to review the next shape.
4. Click <Return> to confirm when prompted to leave the model at
the optimized shape.
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NOTES
5. Compare the original design to the new one. In the original design,
the catch displacement was not sufficient to clear the latch, the
stresses were higher, and it was heavier. The new design has
sufficient displacement, less stress, and is lighter.
6. Switch to the standard application. Save and erase the model.
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Running Sens i t i v i ty and Opt imizat ion Studies Page 9-25
NOTES
MODULE SUMMARY
You have learned:
• How to run local sensitivity and global sensitivity studies tounderstand the effects of shape change on the model.
• How to run an Optimization Study and replace the Pro/ENGINEERpart with the optimized shape that Pro/MECHANICA developed.
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Page 10-1
Module
Running AnalysesIn this module, you will apply all you have learned to analyze and
optimize a plate-with-a-hole part.
Objectives
After completing this module, you should know how to:
• Define and run static analyses.
• Create design parameters.
• Define and run global sensitivity studies.
• Define and run optimization studies.
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Page 10-2 Fundamenta ls of MECHANICA STRUCTURE/THERMAL
NOTES
Model Description
The part is a 10 x 10 x 0.125” steel plate, with a 2” diameter hole through
its center. The hole can move along a 45° line from the upper left hand
corner, 2” from each edge, to the lower right hand corner, 2” from each
edge. The plate is subjected to a tensile load of 10,000 lbf on its vertical
sides. The model is shown in the following figure.
Figure 1: A Plate with A Hole
Task 1. Perform a static analysis on the design.
1. Perform a static analysis on the design as it exists. Your instructor
will review your results and modeling technique with you.
Task 2. Create a design parameter.
1. Create a design parameter to move the hole along the 45° line.
Task 3. Run a global sensitivity study.
1. Run a global sensitivity study to learn how von Mises stress is
affected by the hole’s location.
2. Record the hole location for minimum stress. Show your
instructor the results.
� Hole Location for Minimum Stress _______________
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Running Analyses Page 10-3
NOTES
Task 4. Define and run an optimization study.
1. Define and run an optimization study to find the hole location that
minimizes von Mises stress.
� Test the optimizer by starting the optimization far from the
minimum value determined in the global sensitivity study. Start
the optimization with the hole’s design parameter value at
minimum of its range.
� Record the hole location for minimum stress. Show your
instructor the results.
� Hole Location for Minimum Stress ________________
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Page 11-1
Module
Advanced ExercisesIn this lesson, you will work with additional exercises to help further
your development in Pro/MECHANICA.
Objectives
After completing this module, you will be able to:
• Describe the purpose of spot-welding.
• Desiree the purpose of contact analysis.
• Desiree the purpose of transient thermal analysis.
• Desiree the purpose of large deformation analysis.
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NOTES
INTEGRATED MODE CONTACT FUNCTIONALITY
You can use contact analysis to solve design problems where parts come
into contact, but the exact regions that touch are unknown. Examples of
these parts are rollers pressing against each other, press fits, rotating gears
or shaft assemblies. Contact analysis is applicable whenever the model
stiffness or load path changes as a function of the applied load.
Before running a contact analysis, you first must define contact regions.
Contact regions indicate which curves or surfaces may touch during a
contact analysis. Pro/MECHANICA ignores contact regions for analysis
types other than contact. Additionally, contact regions are frictionless and
will only transfer normal forces.
When running a contact analysis, Pro/MECHANICA calculates the
detailed stress gradients and deformations found in contact regions that in
some cases may cause the part failure. Determining stresses and
deformations in a contact analysis is a non-linear problem requiring an
iterative solution scheme. The non-linearity is due to the contact area
varying non-linearly with the applied load.
Pro/MECHANICA uses advanced P-element technology and geometric
elements with a penalty solution method for achieving a converged contact
solution. This procedure is fully adaptive and automated and requires no
artificial constraints such as the gap elements used in conventional finite
element codes.
Running Contact Analyses
Contact analysis in Pro/MECHANICA is considered frictionless; the
interface in contact is assumed to be perfectly lubricated.
When using contact analysis on your own models, you should be aware of
the following limitations:
• You cannot use enforced displacements on contact regions.
• You can only run standard or global sensitivity design studies andoptimization with a contact analysis; local sensitivity design studies
can not be run.
• You can not use the iterative solver.
• You cannot combine results from two load sets.
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NOTES
• The contact solution is computed for solid elements only.Pro/MECHANICA will not create contact regions on surfaces with
shell or beam elements.
Pro/MECHANICA Structure handles moderate displacements and
rotations. These displacements and rotations are small enough so that the
Small Displacement Theory is adequate for element calculations, but large
enough that significant rotation of element normals or significant relative
tangential motion of the two surfaces of contact occurs. For 3D models,
the allowable inter-penetration tolerance is one-half the minimum “length”
of the two surfaces defining a contact region, where “length” represents
the square root of the surface area.
Defining Contact Regions
You can define the contact regions manually or automatically. However, if
you use the automatic option, and the assembly is complex (many possible
contact surfaces), some contact regions that are not needed may be
defined. To prevent longer run times, you should delete the excess contact
icons. For a complex model, this can be cumbersome, thus, use this option
with care.
Defining Contact Analysis Measures
There are two default global measures that are calculated for every contact
analysis:
• contact_area: Sums the total area of all the contact regions in themodel.
• contact_max_pres: Tracks the maximum pressure in any of thedefined contact regions.
You can also set up user-defined measures to track five attributes of a
single contact region. These are very helpful when your assembly contains
multiple contact regions:
• Contact area • Maximum contact pressure
• Average contact pressure • Contact load
• Force
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NOTES
Setting Contact Analysis Options
The following options are available when defining contact analyses.
Specifying Load Increments
For contact analyses, you can enter a value for the Number of Load
Increments which specifies the steps at which Pro/MECHANICA
calculates results. This enables you to see how measures vary with the
load. This is similar to performing a global sensitivity with a design
parameter on the load (if that were possible in Structure).
You will use the default of 1 for number of load increments. This option
tells Pro/MECHANICA how to apply the loads or enforced displacements
to the model incrementally. You can set the number of load increments to
more than 1 if you want to view any contact measures as a function of the
applied load. For example, use a value larger than 1 if you need a plot of
contact area vs. applied load.
In conventional FEA (h-codes), the contact solution accuracy is dependent
on the load increment. Pro/MECHANICA, on the other hand, gives you
solution accuracy regardless of what load increment you specify.
Refining the Localized Mesh
Localized Mesh Refinement is available for achieving accurate contact
pressures in the model.
If Localized Mesh Refinement (often called h/p adaptive refinement) is
selected, the mesh will automatically be refined near the contact region to
improve the pressure accuracy. However, Localized Mesh Refinement
does increase analysis run time.
Contact analyses are run for a variety of reasons. One reason to define a
contact analysis is to calculate stresses at an interface of two parts that are
contacting each other. Another reason to run a contact analysis is to
accurately simulate the load transfer between parts, where the maximum
stress in the model is not at the contact zone. For this type of analysis,
localized mesh refinement is not needed, and should be turned off to save
run time.
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Advanced Exerc ises Page 11-5
NOTES
TRANSIENT THERMAL ANALYSIS
For engineering processes that involves heating and cooling, the
transitional period of time is of great interest. The analysis must be
modified to take into account the change in internal energy of the body
with time. In Pro/MECHANICA, this type of data is obtained through a
Transient Thermal analysis.
Fundamentals
When evaluating a design, you may need to investigate what will take
place between material bodies as a result of a temperature difference. This
energy transfer between two bodies (commonly referred to as heat) may
be considered in steady-state or in a transient state.
Thermodynamics deals with systems in equilibrium - it may not be used to
predict how fast a change will take place. Systems in equilibrium are
considered to be in steady-state.
Heat transfer is used to predict the rate at which this exchange will take
place under specified conditions. Bodies not in equilibrium are considered
to be in a transient phase.
Transient Heat Transfer
When bodies are suddenly subjected to a change in environment, some
time may elapse before an equilibrium temperature condition will exist in
the body. Until then, the body is in an unsteady state.
Many engineering problems are concerned only with the steady-state heat
transfer of a part or assembly. This type of information can be obtained by
running a Steady-State Thermal analysis in Pro/MECHANICA.
However, for engineering processes that involve heating and cooling, this
transitional period of time is of great interest as well. The analysis must be
modified to take into account the change in internal energy of the body
with time. In Pro/MECHANICA, this type of data is obtained through a
Transient Thermal analysis.
Whenever there exists a temperature difference in a medium or between
media, heat transfer must occur. This exercise deals with two modes of
heat transfer: conduction and convection.
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NOTES
Thermal Conduction
Conduction is the heat transfer mode that occurs when a temperature
gradient exists in a stationary solid or fluid. Conduction is the transfer of
heat through materials without net mass motion of the material.
The general equation for heat transfer by conduction is:
q =-kA dT/dx where:
q is the rate of heat flow in x-direction
k is the thermal conductivity
A is the area normal to x-direction through which heat flows
dT/dx is the temperature gradient in the x-direction
dT is the temperature change in the x-direction and dx is increment in
length in x-direction
Thermal Convection
Convection is the heat transfer mode that occurs between a surface and
moving fluid when they are at different temperatures. It is the process inwhich thermal energy is transferred between a solid and a fluid flowing
past it. The general equation for heat transfer by convection is:
q = hA ∆T
where:
q is the rate of heat flow via convection
h is the heat-transfer coefficient (also known as the film coefficient)
A is the surface area through which heat flows (convection area)
∆T = Tw -T∞, (temperature potential for heat flow away from surface)
Tw is the wall (surface) temperature and T∞ is the bulk temperature
(average fluid temperature far away from wall)
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NOTES
Defining the Measures
The Transient Thermal analysis has three default measures that are
evaluated over the model at each time step. They are:
• min_dyn_temperature
• max_dyn_ temperature
• max_ flux_ mag
Any information that you want graphed against time, other than these
measures, has to be specified as a user-defined measure before an analysis
is run.
The options for Quantity are:
• Temperature
• Heat Flux
• Temperature Gradient
• Driven Pro Parameter
• Time
The options for Spatial Variation are:
• At Point
• Max Over Model
• Range Over Model
• Min Over Model
• Max Abs Over Model
The options for Time Evaluation are:
• At Each Time Step
• Maximum
• Minimum
• Maximum Absolute
• At Time
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NOTES
LABORATORY PRACTICAL
Goal
To gain more experience with idealizations and analyses.
Method
In the first exercise, you will create and analyze the spot welded sub-
assembly. The overall stress in the sub-assembly can be determined, as
well as any excessive stress concentrations at the location of the spotwelds
In the second exercise, you will use Pro/MECHANICA to determine:1)
The stress on the mounting surface of the pin. 2) The values for the
contact area and contact pressure. 3) Any unreasonable hot spots in the
latch mechanism.
In the third exercise you will set up and run a transient thermal analysis.
In the fourth exercise, you will set up and run a large deformation
analysis.
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NOTES
EXERCISE 1: Creating and Analyzing Spot WeldedSub-Assemblies
Overview
A spot weld consists of a beam that is fused to a surface over an area
defined by the diameter of the weld. You can use spot welds to model
welded structures and bolted connections. When you use spots welds, you
must specify both the diameter of the weld and the material. The length of
the weld is determined by the location of the fusion points on each surface.
Spot welds can be used in both part mode and assembly mode, but patterns
and zero-length spot welds are not supported.
In this lesson, imagine the following scenario. You are the lead engineer
for a company that makes motor-controlled robots for picking up heavy
objects. Due to marketing demands, engineering has decided to use a
heavier, more powerful motor. The current motor rests in a u-channel that
is spot welded to an electronics barrier shelf. This shelf then slides into the
framework of a larger assembly. The team you are working with is
worried that the added weight of the new motor will cause excessive
deflection in the u-channel (the new motor weighs 1000 N). A deflection
of more than 2.54 mm would cause the motor to come in contact with the
lower level of the assembly. For this reason, they want to move to a
continuous seam weld instead of spot welds. From a labor point of view,
that option is very expensive and your boss wants you to make sure it is
absolutely necessary.
The motor has a 152 mm x 406.4 mm base attached to the bottom of the
U-Channel. The four spot welds are placed at 152.4 mm intervals between
them. Because the parts are thin, you will define the assembly as a shell
model. The spot welds are 25.4 mm diameter and 6.35 mm long.
Task 1. Define the surface pairs in part mode to model the assembly as
a shell model.
1. Set your working directory to the folder that corresponds to the
name of the current module.
2. Open the SPOT_WELD.ASM. The units are mmNs. Notice the
there is a 6.35 mm gap between the parts.
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Page 11-10 Fundamenta ls o f Pro /MECHANICA
NOTES
3. Enter Pro/MECHANICA Structure to test the sheet metal
compression. Notice no midsurfaces have been defined.
Note:
Recall that when simulating an assembly as a shell model, the
midsurfaces have to be defined at the part level.
4. Open the part U_CHANNEL.PRT. Enter Pro/MECHANICA
Structure. Auto-detect and compress the surface pairs. Save the
part and close the window.
5. Repeat the procedure to compress the SHELF.PRT.
Task 2. Idealize the assembly as a shell model. Assign material
properties.
1. Switch to the assembly window.
2. Enter Pro/MECHANICA. Click Applications > Mechanica >
Continue > Structure.
3. Compress the surface pairs. Click Model > Idealizations > Shells
> Midsurfaces > Compress > Shells only > ShowCompress.
4. Return to the STRC MODEL menu when finished.
5. Assign STEEL as the material for both parts.
Task 3. Create the spot welds.
1. Click Idealization > Spot Welds > Create.
2. Define the references.
� For the first surface, select the bottom surface of the shelf to be
welded.
� For the second surface, select the top right flange surfaces of
the U channel.
� For the points, select the 4 datum points on the right side of the
shelf and the 4 datum points on the right side of the U channel.
� Click Done Sel to finish.
3. Define the weld diameter. Enter [25.4 ].
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Advanced Exerc ises Page 11-11
NOTES
4. Assign STEEL as the material for the spot welds when prompted.
The system displays the spot weld icons.
5. Repeat the steps above to create spot welds on the left-hand side.
Task 4. Define the boundary conditions. The surface regions for the
boundary conditions have already been defined for your convenience.
1. Create a surface constraint to represent the slot that clamps the
edges of the shelf.
� Click [Create a surface constraint].
� Enter [slot ] as the name.
� Select the two surface regions that represent the clamp area on
the shelf part, as shown in the following figure.
� Fix all 6 DOFs.
2. Create a load to simulate the motor.
� Click [Create a surface load].
� Enter [motor ] as the load name.
� Select the rectangular surface region on the bottom of the U
channel.
� Enter [-1000 ] as the FORCE component in the Y direction.
Figure 1: Assembly With All The Boundary Conditions And Spot Welds Defined
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Page 11-12 Fundamenta ls o f Pro /MECHANICA
NOTES
Task 5. Create and run a static analysis.
1. Define a static analysis named [spot_weld ]. Accept all the
defaults.
2. Run the spot_weld analysis.
3. A confirmation window warns that there are originally 2 disjoint
bodies in the model. They should be properly connected by spot
welds. Click Confirm to proceed.
Task 6. Display and interpret the results.
1. Create and show a displacement result window. Note the
maximum displacement in the model.
Figure 2: Displacement Fringe Plot
2. Create and show a von Mises stress result window. Note the
maximum stress in the model.
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Advanced Exerc ises Page 11-13
NOTES
Figure 3: Von Mises Fringe Plot
3. Do the spot welds create any excessive stress concentrations on the
shelf?
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Page 11-14 Fundamenta ls o f Pro /MECHANICA
NOTES
EXERCISE 2: Contact Problems
Overview
The following figure shows a latch mechanism used to secure a small
electronic box on an airplane. When the front compartment door to this
box is closed, the latch is subjected to a horizontal force of 400 N. Further
movement is prevented when it comes into contact with a pin that is
completely fixed to the interior skin of the aircraft.
As an engineer, you are concerned about stresses on the mounting surface
of the pin due to this contact. In addition, you want to check for any
unreasonable stresses in the latch or pin due to the contact pressure.
Finally, some of your team thinks the mechanism is over designed and that
mass should be taken out of the latch.
Figure 4: Latch Mechanism
Task 1. Retrieve the latch model and enter MECHANICA.
1. Open LATCH.ASM. Verify that the units are mmNs.
2. Enter Pro/MECHANICA. Click Applications > Mechanica >
Continue > Structure.
Task 2. Assign STEEL as material for both parts.
1. Click Materials. Add STEEL to the model.
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Advanced Exerc ises Page 11-15
NOTES
2. Click Assign > Part. Select both parts, followed by Done Sel.
3. Click Close when finish.
Task 3. Constrain the latch assembly.
1. Constraint the bottom of the latch so that the latch can only move
freely in the x-direction.
� Click [Create a surface constraint].
� Select the bottom surface of the latch as shown in the following
figure.
� Free translation in x-direction. Fix all other DOFs. Click OK to
finish.
Figure 5: Latch Surface Constraint
2. Constrain the back of the pin.
� Click [Create a surface constraint].
� Select the back surface of the pin as shown in the following
figure.
� Fix all 6 DOFs. Click OK to finish.
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Page 11-16 Fundamenta ls o f Pro /MECHANICA
NOTES
Figure 6: Pin Surface Constraint
Task 4. Apply the load.
1. Apply a load of 400 N in the x direction as shown in the following
figure.
Figure 7: Surface Load
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Advanced Exerc ises Page 11-17
NOTES
Task 5. Define the contact regions.
1. To define a contact region, click Model > Contacts > Create >
Face/Surface.
2. Select the surfaces that may be in contact (meshed in the following
figure).
3. Click Done Sel. Note that the contact icon appears.
4. Review the contact region.
� Click Review.
� Click the contact icon. The system highlight surfaces in red.
Figure 8: Contact Region Surfaces
Task 6. Define the measures.
1. Set up any relevant measures you need for this analysis. Two
contact measures are automatically defined for the contact analysis
pressure area.
Task 7. Define the contact analysis.
1. Click Analyses > Static > New.
2. Enter [contact_spa ] as the name.
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NOTES
3. Click the Convergence tab.
� Make sure the Convergence Method is Single-Pass Adaptive.
� Select Localized Mesh Refinement.
� Click OK > Close.
4. Run the CONTACT_SPA analysis.
5. Confirm when prompted for error checking.
6. Click Confirm when system warns that there 2 disjoint bodies in
the model. Since there is a contact region defined between the 2
bodies, the model is sufficiently constrained.
7. Monitor the process using the summary file. Notice that the
Pro/MECHANICA recognizes the contact area is small and
automatically refines the mesh in that area.
Task 8. View and interpret the results.
1. Create and display an animated displacement fringe plot. Verify
that the loading is causing the latch to come into contact with the
pin. Note that the latch may appear to pass through the pin. This
happens because the magnitude of the displacement is magnified
(scale factor).
Figure 9: Displacement Result Window
8. Create and display a non-animated von Mises stress fringe plot.
Edit legend scale for clearer display as necessary.
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NOTES
Figure 10: Von Mises Stress Fringe Plot
9. Notice that the contact area is very small. Is this an effective latch
mechanism? From the stress level, you can conclude that the latch
mechanism is over designed.
Task 9. The values at the mounting surface are reasonable. However, if
the team makes design changes to reduce mass in the mechanism, these
stress concentrations could pose problems. Take a closer look at the
contact area and pressure on the latch.
1. Create a cutting surface to look at the inside of the model.
� Click Insert > CuttingSurfs.
� Accept the default WCS as well as the XY plane.
� Enter [30%] for the cutting depth.
� Click Accept to finish.
10. Dynamically modify the cutting plane.
� Click Edit > Cutting Plane.
� Click the Dynamic option.
� Drag left mouse button to move the cutting plane.
� Click the middle mouse button to finish.
� Click Accept to finish.
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NOTES
Figure 11: Stress Inside Of The Model Using The Cutting Plane
11. Exit the results interface.
12. Switch to the standard application. Save and erase the model.
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Advanced Exerc ises Page 11-21
NOTES
EXERCISE 3: Running Transient Thermal Analyses
Overview
The following figure shows a rocket-engine nozzle for a prototype shuttle
between Earth and the new Space Station. At the time of ignition, this
nozzle will be subjected to hot gases at 1648.8 °C. The gases combine and
reach their maximum temperature over time.
The part is coated with a ceramic material having the following properties:
Thermal Conductivity k=10,781 W/m o
C
Specific Heat c=1.624 kJ/kgoC
Density ρ=4.52 103 kg/m
3
The convective heat-transfer (film) coefficient between the nozzle and the
gases is 4 103 kW/ m
2 oC . The nozzle is initially at –17.7
oC.
Figure 12 A Rocket-Engine Nozzle Prototype
Your job as engineer is to determine if the rocket's engine is on too long
before launch, thus, over-heating the nozzle. The engine is on for 100
seconds before lift off. There is an electronic warning switch located on
the inner surface of the nozzle that will alert launch control if the nozzle
temperatures are higher than 1371°C. In addition, you need to ensure that
the temperature gradients in the coating are not too large during the initial
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NOTES
start-up. There can be no more than a 400°C difference between the inner
and outer surfaces of the nozzle. Finally, the thermal protection engineerswould like to correlate data with your analysis and have asked you to
provide complete temperature profiles for two points during the count-
down; one half-way through ignition (50 seconds), and one right before
lift-off (100 seconds). You will use Pro/MECHANICA to determine:
• How long after start up will it take for the temperature on the ceramic
coating's surface to reach 1371°C.
• If there are any large thermal gradients during ignition that mightcause the ceramic coating to crack.
• What the temperature profile looks like half-way through ignition andright before lift-off.
Considerations for Transient Thermal Analyses
Some issues to consider when using Transient Thermal Analysis in
Pro/MECHANICA are as follows:
• The model cannot contain multi-point constraints.
• It is available for 3D models with isotropic elements only (noshells/beams).
• It is available for standard analyses only (no sensitivity oroptimization).
The time dependence is a multiplier function, so the user can only enter
loads that also have a spatial variation as the product of two functions. For
example:
f(x,y,z) * f(time)
NOT f(x,y,z,time)
Task 1. Retrieve the model and assign the material properties.
1. Open NOZZLE.PRT. Note that the unit system is mmNs.
2. Enter the Pro/MECHANICA Thermal module.
3. The material properties of the ceramic file and the convection
coefficient are as follows:
� Thermal Conductivity k=10,781 W/m o
C
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Advanced Exerc ises Page 11-23
NOTES
� Specific Heat c=1.624 kJ/kgoC
� Density ρ=4.52 (103) kg/m
3
� Young’s Modulus E = 400,000 N/mm^2
� Convection Coefficient h = 4 (103) kW/ m
2 oC
Using the units found in the strategy guide, the above information can
be converted as follow:
� Specific Heat Capacity c = 1624 m^2/sec^2C
� Thermal Conductivity k =10781 N/secC
� Density ρ== 4520 kg/m^3
� Convection coefficient h = 4000 mW/mm^2C
� Young's Modulus E = 400,000 N/mm^2
4. Create a new material named CERAMIC and assign the material
properties to the part using the information shown above.
Task 2. Apply the convection boundary conditions with a variable bulk
temperature. The gasses flow in at a rate such that temperature values per
unit of time are defined in a text file..
1. Click [Surface convection condition]. The CONVECTION
CONDITION dialog box appears.
2. Enter [flame ] for the name.
3. Accept the default constraint set.
4. Click [Select]. Select the inside nozzle surface, followed by
Done Sel.
5. Enter [4000 ] for the CONVECTION COEFFICIENT.
6. Enter [1] for the BULK TEMPERATURE.
7. Select the Time Dependant option.
Note:
In this case, the Bulk Temperature is only a factor. The actual
time dependent temperature is defined in the next step.
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NOTES
8. Select Time Dependent > f(x).
9. Select Table from the TYPE drop-down list.
10. Click Import and retrieve the CONVECTION.TXT located in the
current directory.
11. Review the graph.
12. Finish the definition.
Task 3. Define and run a Transient Thermal analysis.
13. Click Analyses.
14. Choose Transient Thermal from the NEW ANALYSIS drop-down
list and name the analysis NOZZLE_THERM.
15. Name the analysis [nozzle_transient].
16. Select the constraint set.
17. On the Temperature tab, enter [-17.7 ] as the initial temperature.
18. On the Output tab,
� Select calculate Heat Flux.
� Choose User-defined Output Intervals.
� Set the number of Master Intervals to 3.
� Select the User-defined Steps button.
� For Interval 0, enter 0 seconds; for interval 1, enter 50 seconds;
for interval 2, enter 100 seconds; for interval 3, enter 120
seconds. Check the Full Results box next to each interval.
19. Click OK > Close to finish.
20. Run the analysis. Monitor the process using the summary file.
Task 4. Review the results.
1. Create a graph for max_dyn_temp measure vs. time. The result
window should appear as shown in the following figure.
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Advanced Exerc ises Page 11-25
NOTES
2. Using the following graph, determine at what time the nozzle
reaches a temperature of 1371 °C: ____________ . Is it prior tolift-off (100 seconds)? _______________
3. Create a temperature gradient fringe plot at 50 and 100 seconds.
Does the temperature gradient exceed 400 degrees C anywhere in
the model?
4. Create a temperature distribution fringe plot at 50 and 100 seconds.
This fringe plot could be used to correlate to experimental data.
5. Exit the results interface.
6. Switch to the standard application. Save and erase the model.
Figure 13: Maximum Dynamic Temperature vs. Time
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Page 11-26 Fundamenta ls o f Pro /MECHANICA
NOTES
EXERCISE 4: Analyzing Large Deformation
Overview
The following figure shows an implant for an eye. As an engineer, you
are concerned about stresses and displacement around the tips of the
implant.
Task 1. Investigate the symmetric model.
1. Retrieve the EYE_IMPLANT.PRT located in the current
working directory.
2. The model is cut in half to take advantage of its symmetry.
Investigate the last cut by redefining it.
Figure 14: Symmetric model of Implant
3. Quit redefining without changing anything.
Task 2. Assign the material properties.
1. Click Application > Mechanica. Click Continue in the UNIT
INFO dialog box.
2. Click Structure from the MECHANICA menu.
3. Click Model > Materials.
4. Select Nylon from the MATERIALS IN LIBRARY.
5. Add the Nylon to the model.
6. Click Assign > Part.
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Advanced Exerc ises Page 11-27
NOTES
7. Select the eye implant part, followed by Done Sel.
8. Close the MATERIALS dialog box.
Task 3. Create a constraint for symmetry
1. Click Constraints > New from the CONSTRNTS menu followed
by Surface.
2. Enter [symmetry ] as the constraint name.
3. Click the [Select] icon under SURFACE(S) and select the cut
surface as shown in the following figure.
Figure 15: Surface for Symmetry Constraint
4. Click Done Sel to finish.
5. Click the [Select] icon under COORDINATE SYSTEM and
select the locate coordinate system CS1 previous created, as shown
in the following figure.
Figure 16: Coordinate System for the Symmetry Constraint
6. Fix Z Translation and choose Free for all the DOF's. The data form
should look like the following figure.
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NOTES
Figure 17: Symmetry Constraint Data Form
7. Click OK to finish.
Task 4. Create a constraint on bottom of the implant.
1. Click New from the CONSTRNTS menu followed by Surface.
2. Enter [eyeball ] as the constraint name.
3. Click the [Select] icon under SURFACE(S) and select the
bottom surface as shown in the following figure.
Figure 18: Eyeball Surface Constraint
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Advanced Exerc ises Page 11-29
NOTES
4. Click Done Sel to finish.
5. Change the coordinate system to the World Coordinate System by
selecting WCS from the SIM CSYS SEL menu.
Figure 19: WCS for the Eyeball Constraint
6. Fix X, Y, Z Translation and choose Free for all the DOF's. The
data form should look like the following figure.
Figure 20: Eyeball Constraint Data Form
7. Click OK to finish.
Task 5. Create a load at the end of the long segment
1. Click Loads from the STUC MODEL menu. Click New > Surface.
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NOTES
2. Click the [Select] icon under SURFACE(S) and select the
surface region as shown in the following figure.
Figure 21: Tip Load Surface
3. Select the world coordinate system WCS from the SIM CSYS SEL
menu.
4. Select Total Load > Interpolated Over Entity from the
distribution drop down list.
5. Click Define to specify the interpolation points.
� Turn on the datum point display as necessary.
� Click Add in the INTERPOLATED OVER ENTITY dialog box.
� Select PNT0, PNT1, PNT2, as shown in the following figure.
Figure 22: Interpolation Points
� Click Done Sel > Done/Return when finish.
� Enter [1] for the second point and preview the load. The load
should look like the following figure. Click OK to finish.
6. In the FORCE/MOMENT data form, enter [-0.0008 ] as the Y
force component. The FORCE/MOMENT data form should look
like the following figure.
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NOTES
Figure 23: Interpolation Points for the Tip Load
Figure 24: Tip Load Data orm
7. Click OK to finish.
Task 6. Define a large deformation analysis.
1. Click Analyses. Accept the default Static from the NEW
ANALYSIS drop down list.
2. Click New to define a new static analysis. In the STATIC
ANALYSIS DEFINITION dialog box, accomplish the following
steps:
� Enter [large_def ] as the analysis name.
� Accept the default constraint set.
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NOTES
� Accept the default load set.
� Check the Calculate Large Deformations check box under
the NONLINEAR OPTIONS.
� Accept the default Single-Pass Adaptive from the METHODS
drop down list on the CONVERGENCE tab.
� Click the LOAD INTERVALS tab, and examine the options.
You can use the Number of Intervals to run the analysis at
certain load intervals. To save time, accept the default interval
1.
� Click OK to close the STATIC ANALYSIS DEFINITION dialog
box.
3. Click Close to close the ANALYSES dialog boxes.
Task 7. Run the analysis.
1. Click Run from the MEC STRUCT menu.
2. Click Start in the RUN dialog box.
3. Click Yes, when prompted whether you want error detection.
4. Click Summary in the RUN dialog box and monitor the analysis
process.
5. When the analysis run is finished, close the summary window and
click Done to close the Run window.
Task 8. Create the result windows.
1. Click Results from the MEC STRUCT menu.
2. Click No when prompted whether you want to save the model. The
result interface is displayed.
3. Create a window to display the displacement.
� Click Insert > Result Window.
� Name the result window DISPLACEMENT.
� Click the large_def\ in the CURRENT DIRECTORY.
� Click Accept.
� Fill out the data form as shown in the following figure.
� Click Accept to finish.
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NOTES
Figure 25: Definition for the Displacement Result window
4. Create a result window to display the stress using the same
procedure. Fill out the data form as shown in the following figure.
Click Accept to finish.
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NOTES
Figure 26: Definition for the Stress Result Window.
Task 9. Display the result window and examine the results.
1. Click View > Display from the UNTITLED window.
2. Select both windows and click OK.
3. Select both windows. Press <Shift> key and click both windows.
The borders of both windows should be highlighted in yellow.
4. Play the animate. Stop when finished.
5. Notice there are only two frames for each result window. Had you
specified more intervals when you defined the analysis, there
would have been more frames generated for the result window.
6. Click File > Exit Results.
7. Choose No when prompted.
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NOTES
8. Save and erase the model.
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MODULE SUMMARY
You have learned:
• How to define spot weld idealizations.
• How to include contact regions in an analysis.
• How to define a transient thermal analysis.
• How to define a large deformation analysis.
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Page 12-1
Module
Fatigue AdvisorThis module presents the fundamentals of Fatigue Advisor, as well
as a tutorial demonstrating how to conduct a fatigue analysis.
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NOTES
OVERVIEW
Pro/MECHANICA offers a tool called Fatigue Advisor, which can be
used to evaluate the potential of a model to fail due to fatigue damage. The
solving engine behind Fatigue Advisor is a product of nCode
International, a world leader in fatigue analysis. Through a partnership
between nCode and PTC, Fatigue Advisor is now accessible from within
the Pro/MECHANICA interface.
In general, fatigue may be defined as:
• Failure under a repeated or otherwise varying load, which neverreaches a level sufficient to cause failure in a single application.
• The initiation and growth of a crack or growth from pre-existing defectuntil it reaches a critical size.
As this definition suggests, to address the entire phenomenon of fatigue,
we must consider both the initiation and growth of a crack. The focus of
Fatigue Advisor is to predict the initiation of cracks. It uses a strain based
analysis (EN analysis) to predict this initiation. It does not address the
Linear Elastic Fracture Mechanics (LEFM) associated with crack growth.
The goal of Fatigue Advisor is to accomplish one of the following:
• Ensure an engineer that a particular model will not fail due to fatiguedamage throughout it’s desired life.
• Allow the engineer to optimize the model to eliminate fatigueproblems.
• Alert the engineer that, if the problems can not be eliminated throughoptimization, the model should be given to a fatigue expert for
additional attention.
To perform and analysis in Fatigue Advisor the following input is
required:
• Material properties (additional)– Ultimate Tensile Strength (UTS)
• A previously defined Pro/MECHANICA static analysis
• Load history information – characteristics of the loading
• Desired Life of the component
• Correction factors for surface treatment (optional)
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NOTES
The results available from Fatigue Advisor are:
• Log life
• Log damage
• Confidence of life
• Factor of safety
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NOTES
LABORATORY PRACTICAL
EXERCISE 1: Piston Fatigue
Figure 1: A Petrol Engine Piston
You are designing a petrol engine for a new range of small cars. It is a 4-
cylinder unit of 1100cc capacity with 90 ft.lb. torque. One of the
components that need analyzing is the new piston. Pistons have never been
known to fail through fatigue in the past but you are now required to prove
this before the component progresses to the next stage in the design.
Your colleague has provided you with Pro/ENGINEER geometry of ¼ of
the piston. The chief engine designer has estimated that each piston has a
force of 900 lbf. applied to the crown (i.e. 225 lbf. total on ¼ piston
model.) The material chosen is an aluminum alloy (details given in the
following table). The new engine has a target life of approximately
200,000 miles or 600 million cycles under a peak-to-zero loading.
Method
• Determine whether the piston is likely to suffer a premature fatigue
failure.
• Find the location that any cracks will start to form so the test engineerknows where to inspect after the tests are completed.
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Fat igue Advisor Page 12-5
NOTES
• Determine the permitted factor of safety on load to determine howsensitive the piston is to overstress.
Table 1 Fatigue Parameters
Material Loading
Units lbf, in Desired Endurance 6e+008
Name AL2014 Load type Constant Amplitude
Material Type Aluminum Alloys Amplitude Type Peak-zero
Surface finish Polished Distribution Total load
Cut-off 2e+016 Force component Y = -225
UTS 70051
E 1.06e+007
µ 0.33
Kf 1
Goal
This is a typical example of an analysis where fatigue failure is not
expected but verification is still required. The piston will have to endure a
very high number of cycles; most fatigue analysis is only strictly valid for
less than 1E8 cycles. You will learn the following procedures:
• How to apply material fatigue properties to a Pro/MECHANICA solidmodel.
• How to apply fatigue load cases to the model.
• How to set up a static stress and fatigue analysis run.
• How to enable the Factor-of-Safety calculation using the Edit Session
option.
Task 1. Set the fatigue material properties.
1. Set your working directory to the folder that corresponds to the
name of the current module.
2. Open PISTON.PRT and familiarize yourself with the model.
3. Enter MECHANICA. Click Applications > Mechanica >
Continue > Structure. Notice that the model is properly
constrained for your convenience.
4. Assign material properties to the piston.
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NOTES
� Click Model > Materials.
� Add AL2014 to the MATERIALS IN MODEL.
� Click Assign > Part.
� Select the piston part, followed by Done Sel.
5. Define the fatigue properties.
� Click Edit, and click the Fatigue tab.
� Enter the properties given in the previous table. The dialog box
should appear as shown in the following figure.
� Click OK > Close to finish.
Figure 2: Fatigue Definition Form
Task 2. Define a surface load. The load simulates repetitive combustion
that causes fatigue.
1. Click [Create a surface load].
2. Enter [Combustion ] as the name.
3. Click [Select] under the SURFACE(S).
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Fat igue Advisor Page 12-7
NOTES
4. Click the surfaces (meshed in the following figure) that make up
the piston crown.
5. Click Done Sel to finish.
Figure 3: Combustion Load Surfaces on Piston (shown meshed).
6. Enter [–225 ] as the Y force components.
7. Click OK to finish.
Task 3. Setup a static analysis.
1. Click Analyses > Static > New.
2. Enter [piston_static ].
3. Accept the defaults. Click OK > Close to finish.
Task 4. Run the static analysis and display the result.
1. Run the analysis. Monitor the process using the summary file.
2. Create a result window to display the von Mises stress fringe plot.
3. Exit the result interface when finished.
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NOTES
Task 5. Create a fatigue analysis.
1. Click Analyses and select Fatigue from the NEW ANALYSIS
drop-down list
2. Click New. Enter [piston_fatigue ] as the name.
3. Click the Load History tab. Enter the following information.
� Enter [6e8 ] for the DESIRED ENDURANCE.
� Select Constant Amplitude for the LOADING TYPE.
� Select Zero-Peak for the AMPLITUDE TYPE.
4. Click the Previous Analysis tab. Enter the following information.
� Check the Use static analysis results from previous design
study check box.
� Accept the default piston-static for both the DESIGN STUDY
and the STATIC ANALYSIS.
� Set the load to loadset1.
5. Set the PLOTTING Grid to 4. Click OK to finish.
Task 6. Run the analysis.
1. Run the piston_fatigue analysis. Monitor the process using the
summary file as it proceeds.
Task 7. View and interpret the results.
1. Create a result window for the piston_fatigue analysis to display
the Log Life plots.
2. Notice where the fatigue cracks is likely to form. The minimum
life is 1013.544
or 3.5E13, do you think this safety factor is OK?
3. Create a result window for the piston_fatigue analysis to display
the Confidence of Life plots.
4. Notice how the Confidence of Life is all green.
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Fat igue Advisor Page 12-9
NOTES
5. Create a result window for the piston_static analysis to display
the animated von Mises stress plots.
6. Exit the result interface when finish.
Figure 4: Stress and Log Life Plots
Task 8. Enable the FACTOR OF SAFETY option and rerun the analysis.
The Factor of Safety option is switched off by default because it requires
longer run time. Had you created a Factor of Safety result window, the
value would be zero.
1. Turn on the Factor of Safety option using the session
configuration file.
� Return to the top-level menu. Click Configuration > Edit
Session.
� Add the keyword Fatigue_FOS_Calculation. Use <F4> as
necessary.
� Set the value to ON. Use <F4> to view options, as necessary.
� Click Exit when finish.
� Click Save Session As. Accept the default name.
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NOTES
� Click Load File and load the saved file.
2. (Optional) Re-run the Fatigue Analysis. It could take long time
depending on the hardware. Alternatively use the results found in
the same directory generating the result windows.
3. Create and display a Factor of Safety result window.
4. View the Factor of Safety results. The minimum Factor of Safety
suggests a permissible overload of 2.8 times before the fatigue life
is jeopardized.
5. Change the legend for easier interpretation as necessary.
� Click Edit > Legend Value, and select the appropriate value to
edit.
� Use the FOS minimum (2.8 in this example) as the legend
minimum.
� Use around 10 times the minimum as the legend maximum.
6. Exit the result interface.
7. Switch to the standard application. Save and erase the model.
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Fat igue Advisor Page 12-11
NOTES
MODULE SUMMARY
In this module, you learned how Pro/Pro/MECHANICA can be used to
calculate the fatigue life of a typical component.
• If this safety critical component were designed for a life of 10000cycles, would you pass this onto a fatigue expert or would you trust
this analysis?
• If you only required 5000 cycles what would you do?
• What is the value of Fatigue Advisor in this instance?
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Page 13-1
Module
Student ProjectsIn this module you measure your basic Pro/MECHANICA
Structure/Thermal knowledge.
Objectives
After completing this module, you will be able to:
• Assign properties.
• Apply constraints.
• Define loads.
• Run static, thermal, and modal analyses.
• Modify the shape your part with design parameters.
• Use measures.
• Run sensitivity and optimization studies
• Evaluate your results.
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NOTES
STUDENT PROJECTS
Each of the following design projects is outlined in detail. They vary in
degree of difficulty. Choose a project that most closely reflects you area of
interest.
• Flagpole • Driveshaft
• Wing spar • Valve Housing
• Heat Sink • Buckling Ring
• Beverage Can
Hints on how to design the projects are provided in the second half of the
module.
Designing a Flagpole
Design a horizontal flagpole, minimizing mass while keeping maximum
stress safely below yield.
The flag pole must be 4 meters long and extend in the z-direction. It must
be fully constrained at one end to represent the connection to the side of a
building. The other end must have a 100N downward load in the y-
direction representing the weight of the attached flag, and a 15N lateral
load in the x-direction representing wind loading on the flag (we can
ignore wind loading on the pole). Earthquake codes require that the pole
be able to carry 2G's worth of downward seismic loading in addition to the
regular 1G weight of the pole, for a total gravity load of 3G.
Build your model out of the "Steel" found in the Pro/MECHANICA
material library”, which is a general HS low-alloy steel. Shigley &
Mischke list the yield stress of 1212 Hot-Rolled steel to be 193 MPa. We
need a safety factor of 4 on this project. Choose a convergence value for
your static analyses of 10%, and an optimization convergence of 1%. Do
not build the model with beam elements, since we want very specific
stress information across the entire cross-section of the flagpole.
After validating that you've built a good model, incorporate design
variables on geometry and/or material properties to add design flexibility.
Optimize for minimum mass, while maintaining the other design criteria.
Any design with a total mass below 20 kg is acceptable, although there are
some designs with significantly less mass.
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Student Pro jects Page 13-3
NOTES
No picture is shown because there could be many solutions to this
exercise. Your job is to find the one you think is the best and willing to put
into production.
Designing a Driveshaft
Design the lightest truck drive shaft that meets static and modal design
requirements.
You must design a 4 meter long driveshaft that is constrained at one end,
and has a 25,000 Nm axial torque at the other end. Although the loaded
end of the shaft is free to twist about its axis, for the purposes of looking at
realistic mode shapes, it should not be able to move radially or axially
since it represents the end of the shaft connected to the truck's
transmission. Due to packaging constraints, the shaft can have a radius no
greater than1 meter at any point.
The first mode of the shaft needs be greater than 60 Hz, so that engine and
ground terrain loading do not create destructive resonance in the shaft that
would shorten the shaft life.
Build your model out of the "Steel" found in the Pro/MECHANICA
material library, which is a general HS low-alloy steel. Shigley & Mischke
list the yield stress of 1212 Hot-Rolled steel to be 193 MPa. We need a
safety factor of 4 on this project.
Use sensitivity and optimization studies to find the design with the lowest
mass that meets these criteria. Choose a convergence value for your static
analyses of 10%, and an optimization convergence of 1%. Feel free to use
the single-pass adaptive algorithm where appropriate.
After you find the best design, run a pre-stress modal analysis to see if the
stress stiffness (and subsequent frequency of the first mode) is affected by
the torsion load.
No picture is shown because there could be many solutions to this
exercise. Your job is to find the one you think is the best and willing to put
into production.
Designing a Wing Spar
A Wing Support needs to be designed for low weight and displacement
resilience. The loads have been derived from wind tunnel experiments and
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NOTES
have been given to the engineer as a boundary condition for the problem.
Stresses for fatigue failure are also a concern in the design.
Create the part as a shell model, using surfaces to represent the mid-plane
geometry. The part dimensions, in inches, are shown below. Each surface
should have a .2" thickness. The holes' axes must intersect the line that
connects the midpoints of one end of the beam web to the other. The holes
are equally spaced along this line.
Define loads and boundary conditions. The left (or larger) end of the spar
should be immovable. The part is loaded on the top surface(s) with a total
load of (100, -200, 0) in x, y, and z directions, respectively. Run a static
analysis, using convergence of .05%.
Place design parameters on the three holes, allowing them to vary in
radius from .25” to .4”. Using the existing static analysis, run sensitivity
studies and/or an optimization to minimize mass while keeping the
maximum Von Mises stress below 1900 psi and the maximum
displacement magnitude below .0025 inches.
Figure 1: Wing Spar
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Student Pro jects Page 13-5
NOTES
Designing a Valve Housing
ABC Valve Company has an existing line of valves that have been in
production for over 35 years. They have an excellent safety record with
these valves. Lately, ABC Valve Co. has been losing some existing
accounts due to cost. ABC refuses to skimp on quality and safety, but
must find a way to reduce cost. ABC makes over one million valves a
year, and the ability to reduce material costs was judged to be imperative.
As a new engineer with the company, you were sent to Pro/MECHANICA
training. You were asked to evaluate the existing line of valves. After
evaluating each valve you were asked to propose improvements that
would reduce cost, increase valve life, and maintain the current safety
record.
The first part you are to evaluate is a small brass valve that is shown in the
following figure. This valve must be manufactured out of brass, due to the
environment to which it is exposed.
• Naval Brass Material Properties:
• Specific Weight = 0.304 lb/in3
• Modulus of Elasticity = 15,000 ksi
• Poisson's Ratio = 0.35
• Yield Stress = 60 ksi
• Ultimate Stress = 85 ksi
This design meets all OSHA's safety requirements. OSHA allows for
pressure valves to yield at 1.5 times their designed operating pressure.
This little valve is designed to a maximum operating pressure of 600 psi.
Under pressure testing the valve began to yield between 900 - 1,000 psi,
thus meeting the limits. Your assignment is to:
• Build this valve and confirm these test results.
• Propose changes that would reduce material costs while keeping thefailure pressure the same or higher.
There are certain design constraints that your final design must not violate.
You may not reduce the volume that is free inside the valve. For example,
the inside height must remain 0.875 inches, and the ID must remain 1.812
inches. The inside corner radii's can be as large as 0.075 inches. The 0.275
inch base must remain this thick, and top thread length must not change.
The overall height can not change either, due to current design constraints.
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NOTES
The top outside thread is capped with a plastic cap to allow the housing to
hold pressure. This adds essentially no structural strength, so it need not be
modeled.
The bottom inside thread is where the pressure feed is attached, and
should be fixed from translating in all three directions.
A uniform pressure should be applied to all inside areas.
Use Failure due to yielding as your failure criteria on this valve. This is
Max. Distortion Energy Theory (or Von Mises - Henckly Theory). Max
distortion energy theory has been found to agree best with available test
data for ductile materials.
Figure 2: Valve Housing
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Student Pro jects Page 13-7
NOTES
Designing a Heat Sink
You must attach a heat sink to a 20W CPU that has been running too hot
in past designs. This CPU will be mounted to a circuit card assembly for a
flight control computer box in an aircraft. An engineer looks in a vendor
catalog to find a simple “heat sink” that will fit the profile of the CPU. He
discovers that there are 40 different types to choose from that also vary in
price and availability. There is no forced air moving over this heat sink.
The challenge is to select the best heat sink for the job.
The engineer must use Pro/MECHANICA to validate a base line heat sink,
then use sensitivities and optimization to decrease the mass of the part
while maintaining a maximum temperature of 135 degrees F. These
studies will assist the engineer in selecting the proper heat sink for the
application at hand. The initial model will have a 20W heat source placed
on the bottom surface, and a convection of 0.01 placed on the long vertical
faces of the fins.
hstart = 0.01 (lbf /in degree F sec) => free convection or no forced air.
Q = 20 (Watts) = 14.75 (lbf in/sec).
Figure 3: Heat Sink Drawing
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Page 13-8 Fundamenta ls o f Pro /MECHANICA
NOTES
Analyzing a Buckling Ring
Determine the best way to simplify the buckling analysis of a disk under
radial compression.
You are designing components for a jet engine. One of your components
is a complex ring that undergoes a radial (inward) load. You wish to see if
that load is at or above the critical load that will induce linear buckling.
The complex model would take a long time to run, so you would like to
simplify the model, using shells, symmetry, and/or axisymmetric
modeling. Not knowing your buckling mode shapes ahead of time,
however, you're not sure what kinds of simplifications are appropriate. So
you should build a full 3D solid test model with the approximate shape of
your ring, look at the mode shapes, estimate what types of simplification
that you can put on the model, build a simplified test model, and then run
that simplified model to confirm validity.
If the simplified test model gives the same answers as the full test model,
then you can be reasonably confident that the complex model can be
simplified in the same way.
The test model with the same approximate shape as your real-world part
would be an annulus with an outer diameter of 2 meters, an inner diameter
of .2 meters, and a thickness of .02 meters, as shown in the following
figure. The material is “Steel”. Remember to add your constraints and
loads in the current working coordinate system. Build your model with
solid elements. Since buckling analyses take more time to run than regular
static analyses, make sure to use whatever element creation method
necessary such that there are fewer than 100 solid elements, or you will
spend too much time waiting for the analysis to solve. Constrain the inner
radius of the annulus in all 6 DOF. Load the outer radius with an inward
radial load. Run a buckling analysis for the first 5 buckling load factors
(BLF), with all convergences set to 10%
Look at animations of the buckling shapes that correspond to each of the
BLF.
Are all five half symmetric? If so, you could cut the model in half, add
appropriate symmetric boundary conditions, and run it that way. Are all
five quarter symmetric? If so, you could cut the model in quarters, again
adding appropriate symmetric boundary conditions. Are all 5
axisymmetric? If so, you could rebuild this model as axisymmetric.
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Student Pro jects Page 13-9
NOTES
Decide how you wish to simplify the model (half symmetric, quarter
symmetric, or axisymmetric). Then rebuild the test model with shell
elements. Run the simplified test model. Notice that the shell model runs
much, much faster than the solid model.
Compare the BLF and buckling shapes in the simplified shell test model to
those from the solid test model. Are they essentially the same? Does your
simplified model capture a wide enough numerical range of BLF that you
are confident that you've captured the major BLF of concern? If the
answer to both of these questions is “yes”, then your simplification of the
solid model is valid in an engineering sense, and you can expect that a
similar simplification of your real world part would be similarly valid.
Based on either of your models, would the part be able to sustain a
500,000 N load without undergoing linear static buckling?
Figure 4: Ring
Analyzing a Beverage Can
You will create a shell model of a beverage can and determine how much
stiffer the can is with positive pressure inside (before being opened) vs.
with atmospheric pressure inside (after being opened).
If you are starting in Pro/ENGINEER, create the can_body and can_lid
parts. Make sure to start each part with a default coordinate system and
default datum planes. Use an aluminum material for the body and a steel
material for the lid. Auto-pair each part and check the results using the
Shell Compress command. Assemble the parts together, making sure youuse offsets (mate or align) appropriate to allow the shell compressions of
the parts to meet up edge to edge. Check the shell compression of the
assembly for connectivity before preceding.
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Page 13-10 Fundamenta ls o f Pro /MECHANICA
NOTES
If you are starting in Pro/MECHANICA Structure, define the midplane
surfaces for the body and the lid in one part, making sure that associativity
exists around the upper edge.
Apply a breathing constraint on the bottom surface of the can using a
cylindrical coordinate system (i.e. constrain theta and z translations).
There will be two load sets, a pressure load set and a ‘step' load set
(simulating standing on the can):
• Apply a 30 psi pressure load to all the internal surfaces of the can(don't pressurize the rim on top) in a load set called press_load.
Display the load to verify that the pressure is directed outward.
• Apply a -165 lb load in the negative z-direction along a single edge onthe rim of the can (the top surface will be compressed so a load on the
surface will cause an error). Use the load set name step_load. Display
the load to verify its distribution.
Next you will define three analyses. For each analysis, converge to 10%
on Local Displacement, Local Strain Energy and Global RMS Stress.
Allow a maximum p-order of 9 and increase the plotting grid to 7 or more.
The analysis types and load sets are as follows:
• A Static analysis called ‘press_ld_only' will have only the pressureload set applied.
• Another Static analysis will have only the step load applied.
• A Pre-stress Static analysis called ‘pre_sts_step' will have only thestep load applied. Click the Page Down button and verify that the
specified Static Analysis (providing the pre-stress condition) is the ‘
press_ld_only' analysis already defined.
Run the analyses one at a time or together in a design study called
something like ‘can_study'.
Compute the stiffness for the pressurized can and compare to the stiffness
of the ‘open' (de-pressurized) can. Stiffness units are force per length and
the stiffness values can be calculated by dividing the applied load (165
lbs) by the displacement of the top of the can.
If you have extra time you can create a Buckling analysis using the
step_load load set. Find the first two or three Buckling Modes with 10%
convergence on the Buckling Load Factor & Local Displacement & Local
Strain Energy & RMS Stress. Use a maximum p-order of 9 and a plotting
grid of 7 or more.
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Student Pro jects Page 13-11
NOTES
Figure 5: Beverage Can Body
Figure 6: Beverage Can Lid
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Page 13-12 Fundamenta ls o f Pro /MECHANICA
NOTES
STUDENT PROJECT HINTS
Flagpole
1. Build a shell model. Flag poles are generally thin walled, so a solid
model would contain too many elements.
2. Use extruded or lofted surfaces.
3. Apply all loads, constraints, and properties to geometry (curves
and surfaces) not elements, so that if Pro/MECHANICA must re-
mesh as a result of design variable changes, it can.
4. Put the end load and the gravity load in the same load set, for
easier display of results.
5. Use Total Load Applied at Point to apply the load at the end of the
pole.
6. Use Load > Gravity to apply the 3G load, which has a magnitude
of -29.4 m/s^2 (in MNS units) and -29400 mm/s^2 (in mmNS
units).
7. Converge on the quantity of interest, the maximum von Mises
stress measure.
8. The maximum von Mises stress in the model must be below
(193e6/4=) 4.5e7 Pa (in MNS units) or 45 Mpa (in mmNS units.)
Driveshaft
1. Since drive shafts are generally thick walled structures, you should
use solid elements in your model.
2. Shell mesh a surface and then extrude it. If you AutoGEM the
surface, consider the number of elements created, and whether you
can more efficiently hand-mesh the same surface.
3. Note the aspect ratios of the solids you create. This model has a
very simple and smooth load path, so there's no reason not to use
aspect ratios of 20 or 30 to 1. At the same time, though, design
your mesh so that you can change the geometry of the model with
a minimum of automatic smoothening and regeneration by the
engine.
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Student Pro jects Page 13-13
NOTES
4. You must have some sort of constraint at the loaded end of the
shaft. Consider defining a User Coordinate System before defining
the constraint, so that it's in a system other than the World
Coordinate System.
5. Use Total Load Applied at Point to apply the load at the end of the
pole.
6. After running your first static analysis, look at fringe plots of
maximum Von Mises stress and maximum principal stress. Which
one do you consider to be a better failure criteria?
7. The stress in the model (whichever stress criteria you choose to
use) must be below (193e6/4=) 4.5e7 Pa (in MNS units) or 45 Mpa
(in mmNS units.)
8. The default number of requested modes, 4, will be enough to
confirm that the frequency of the first mode is significantly below
the frequency of the next lowest mode.
1.
Wing Spar
All users:
1. The dimensions shown in the diagram refer to the “ideal” part.
Since a shell model uses midsurfaces, you will need to figure out
your dimensions with reference to the midsurfaces.
2. The performance criteria are maximum Von Mises stress and
maximum displacement magnitude. Specify that the static analyses
converge on these quantities.
3. To be able to specify your convergence percentage, you must run
the Multipass Adaptive Convergence Algorithm.
4. If your top surface is actually two separate surfaces, you will need
to place two loads of (50, -200, 0) on each of those surfaces.
5. Make your optimization convergence 1%, and limit your
maximum number of iterations to 20.
If using Pro/MECHANICA in Integrated Mode:
1. The part geometry and material must be in inches.
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Page 13-14 Fundamenta ls o f Pro /MECHANICA
NOTES
2. Careful attention must be paid to the thickness of the beam. These
surfaces will be paired at a later time, so this step is very critical.
We want to have a .2” surface thickness property after
compression.
3. Place an “immovable” displacement constraint on the left hand or
thicker end of the part. The constraints must be on the inside edges
of the surface for them to properly pair during the compression.
The constraints must be for all translations but no rotations.
Valve Housing
1. Use symmetric boundary constraints to reduce the size of the
model. A 30, 45, or 90 degree section would run much more
quickly, and with less disk, than the full 360 degree model.
2. The last paragraph in the instructions that refers to Max. Distortion
Energy Theory (or von Mises - Henckly Theory) means that you
should use Maximum Von Mises stress as your failure criteria. It
should never exceed 60 ksi (60e3 psi), and it should be the quantity
upon which your static analysis converges.
If using Pro/MECHANICA in Integrated Mode:
1. Start your model by creating a DATUM COORD SYS, and
DEFAULT DATUM PLANES.
2. Build your profile on the DTM3, the XY plane of the coordinate
system.
3. When defining your revolved protrusion select Variable as the
REV TO option. Enter a value of about 15 to 20 degrees. Use this
parts symmetry to reduce the GEA model size.
4. When defining the fillets and rounds use the SURF-SURF option.
If you use the default EDGE option, the regeneration will fail if
you Redefine the protrusion to 360 degrees. If you use SURF-
SURF then there is no problem with Redefining the protrusion.
5. As the drawing states all of the unmarked radii are 0.032 inches.
These do not have to remain all the same value. Make them
separate rounds, and do not define relationships between them.
6. To make your design parameters easy to remember, you may want
to modify the dimension cosmetics of the dimension symbols, to
more logical names. For example: Rename a radius dimension
from Rd15 to Rtop_rad.
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Student Pro jects Page 13-15
NOTES
If using Pro/MECHANICA in Independent Mode:
1. Build your geometry on the default XY plane, with the Y-axis as
the valves centerline.
2. For the Model Type use 2D Axisymmetric.
3. As the drawing states all of the unmarked radii are 0.032 inches.
These do not have to remain all the same value. Have them defined
by separate Parameters.
Heat Sink
1. Starting in Pro/MECHANICA Structure, create the surface of
extrusion according to the dimensions given above, and AutoGEM
and extrude this surface 1”.
2. Use AL2014_IPS is the material.
3. Place a “Total” heat load of 14.75 on the base surface.
4. Place a convection coefficient of 0.01 lbf /in deg F sec and Bulk
temperature of 90 deg. F, on the long vertical faces of the fins.
There should be a total of 12 surfaces selected.
Validation Analysis:
1. Convergence Method: Multipass Adaptive.
2. Convergence: Measures: Local Temps & Local & Global Energy
Norms 1%.
Design Variables and Sensitivity Studies:
1. For the fin height, translate the top fin surface. Original height =
0.7”. Final height = .2”
2. For the base thickness, translate the base surface. Original
thickness = .3”. Final thickness =.15”
3. All convection Film Coefficients should range from 0.01 to 1. The
quantity 1 is derived from 2 cfm of airflow that could be
potentially rerouted through the enclosure to the CPU. The
question should be asked “What does a varying convection
coefficient relate to physically”. You should be comparing this
variable to mass flow rate.
4. Plot max_temperature vs. design variable.
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Page 13-16 Fundamenta ls o f Pro /MECHANICA
NOTES
5. Run sensitivities on all the above, referencing the same validation
analysis mentioned before.
Optimization
1. Goal: minimize total_mass.
2. Limits: max_temperature < 135 degree F.
3. Optimization Convergence should be 1%, Maximum # Iterations =
20.
4. Deselect Smooth, Regenerate, & repeat
Extra Credit:
1. Run a sensitivity on the Convection Bulk Temperature from 70 to
130 Deg. F. The question should be asked, “What does a varying
convection bulk temperature relate to physically”. Students should
relate this to the ambient operating temperature of the flight control
computer box in the air craft.
Buckling Ring
1. Since the output of a buckling analysis is a buckling load factorthat represents the critical buckling load over the current load,
enter a magnitude of “1” for the solid model radial load. That way,
the buckling load factor will be equal to the critical buckling load.
If you build quarter or half symmetric models later, make sure to
scale the load so that you are comparing “apples to apples” when
comparing the buckling load factors. If you build an axisymmetric
model, use a value of “1” since axisymmetric loads are input with
the magnitude that they would have on an entire model.
2. Some of your buckling shapes (and BLF) will essentially be
duplicates of each other. This is normal- Mechanica is finding two
different “poles” of the same buckling shape.
3. One criteria for deciding if you've looked at enough BLF might be
the following: if the highest BLF is at least twice the lowest BLF,
then your BLF are not just “clustered” around one particular value,
and it would be very unlikely that a small design change would
make a previously unseen buckling shape (with a higher BLF
value) drop it's BLF in half to become the new, lowest (and hence
most critical) buckling shape.
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Student Pro jects Page 13-17
NOTES
Beverage Can
1. Below are two more efficient ways to analyze the stiffness of the
can (using less elements; therefore, solving more quickly);
however, these simplified models will not be suitable for a
buckling analysis.
2. To save analysis time, you can cut the Pro/ENGINEER assembly
to a smaller section (a 30 degree pie section for instance) and apply
symmetry constraints at the boundaries. A 30 degree section
should require about 1/12 the degrees of freedom to solve than a
360 degree section. Remember to reduce the load appropriately if
using a partial model!
3. Since the model and loads are axisymmetric you could run the
model in independent mode using an axisymmetric model type and
2D-shell elements along the boundary. To do this cut the model to
a section with one side of the cut on the xy plane. Transfer the
model to Independent MEC, verifying that the setting to Use Pairs
is checked. Once in Mechanica do a top view and delete all
geometry except the curves on the xy plane. Make sure all
geometry is in the positive xy plane and use the Axisymmetric
model type. AutoGEM the curves and apply the loads and
constraints.
Note:
If you attempt this Exercise in Independent Mode, use only theouter surfaces of the can -- not the midsurfaces.
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For University Use Only - Commercial Use Prohibited -
Page A-1
Appendix
Using PTC HelpIn this module you learn how to use PTC Help to search for
Pro/ENGINEER information. PTC Help provides quick references
and detailed information on selected topics.
Objectives
After completing this module, you will be able to:
• Start PTC Help.
• Search for specific information about Pro/ENGINEER.
• Obtain context-sensitive help while performing a task.
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Page A-2 Append ix
NOTES
DEFINING THE PTC HELP FEATURES
The PTC Help system is integrated into Pro/ENGINEER. It offers:
• A table of contents, an index, and searching capability.
• Context-sensitive help access.
• Online tutorials focussed on teaching different aspects of the software.
• Expanded help topics available as special dialog boxes.
For addition help, the PTC Technical Support online Knowledge
Database features thousands of suggested techniques. Detailed
information on the Knowledge Database is referenced in the Technical
Support Appendix.
USING THE Pro/ENGINEER ONLINE HELP
The Pro/ENGINEER Online Help can be accessed:
• Using the Main Menu.
1. Click Help > Contents and Index from the Pro/ENGINEER Main
Menu, as shown in the following figure.
Figure 1: Accessing Help from the Main Menu
For University Use Only - Commercial Use Prohibited -
Using PTC Help Page A-3
NOTES
The Pro/ENGINEER Online Help homepage displays in your web
browser window. A list of topics displays in the left frame of the window.
Figure 2: Online Help Homepage
• Using Context-Sensitive Help.
1. Click the icon in the Pro/ENGINEER Main Menu toolbar.
2. Click any icon or any part of the Pro/ENGINEER Main Menu for
detailed information on a particular item. A browser window
displays with a description of the item.
For University Use Only - Commercial Use Prohibited -
Page A-4 Append ix
NOTES
In the following example, clicking the Model Tree icon in the Main Menu
toolbar displays a browser window explaining the Model Tree icon
functionality.
Figure 3: Model Tree Icon
Figure 4: The Help Browser Window for the Model Tree Icon
3. The lower left corner of the browser window displays a See Also
link, as shown in the previous figure
For University Use Only - Commercial Use Prohibited -
Using PTC Help Page A-5
NOTES
4. The See Also link provides a list of related topics, as shown in the
following figure.
Figure 5: The See Also List of Topics
For University Use Only - Commercial Use Prohibited -
Page A-6 Append ix
NOTES
• Using the Pro/ENGINEER Menu Manager.
1. Click the icon in the Pro/ENGINEER Main Menu toolbar.
2. Select any menu command from the Menu Manager.
3. A TOPIC ROUTER browser window opens with a list of topic links
that explain the menu command.
4. Select a topic link.
The X-Section menu command in the Menu Manager displays the TOPIC
ROUTER browser window with a list of two related topics, as shown in the
following figure.
Figure 6: Using the Menu Manager
For University Use Only - Commercial Use Prohibited -
Using PTC Help Page A-7
NOTES
• Using Vertical Menu Commands.
1. Right-click and hold on a menu command until the GETHELP
window displays.
Figure 7: Right-Clicking in Menu Manager
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Page A-8 Append ix
NOTES
Defining the PTC Help Table of Contents
There are four branches in the PTC Help Table of Contents:
Figure 8: Four Main Branches in Help System
Figure 9: Foundation and Additional Modules in Help
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Page B-1
Appendix
Technical Support
In this module you learn about the telephone hotline and the online
services that provide 24 hour / 7 day Technical Support.
Objectives
After completing this module you will be able to:
• Open a Technical Support telephone call.
• Register for online Technical Support.
• Navigate the PTC Products Knowledge Base.
• Locate telephone numbers for technical support and services.
For University Use Only - Commercial Use Prohibited -
Page B-2 Append ix B
NOTES
Locating the Technical Support Web Page
Select SUPPORT from the PTC HOME PAGE, www.ptc.com, or go
directly to www.ptc.com/support/support.htm.
Opening Technical Support Calls via E-Mail
Send email to cs_ptc@ptc.com. Use copen as the e-mail subject.
Use the following format (or download the template from
www.ptc.com/cs/doc/copen.htm):
FNAME First Name
LNAME Last Name
CALLCENTER U.S., Germany, France, U.K.,
Singapore,Tokyo
TELEPHONE NNN NNN-NNNN x-NNNN
CONFIG_ID NNNNNN
PRODUCT
MODULE
PRIORITY
DESC_BEGIN description starts
description continues
description ends
DESC_END
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-3
NOTES
Opening Technical Support Calls via Telephone
For your local Technical Support Center, refer to the Contact Information
telephone list referenced at the end of this module.
When logging a call, you must provide the following information to the
Technical Support Engineer:
• Your PTC softwareConfiguration ID.
• Your name andtelephone number.
• The PTC product name.
• Priority of the issue.
Opening Technical Support Calls via the Web
To open Technical Support calls 24 / 7, select PRO/CALL LOGGERY in the
PTC web site, www.ptc.com/support.
Sending Data Files to PTC Technical Support
To send data files to PTC Technical Support, follow the instructions at:
www.ptc.com/support/cs_guide/additional.htm.
Note:
When a call is resolved, your data is deleted by a Technical
Support Engineer. Your data confidential and will not be shared
with any third party vendors, under any circumstances. You may
request a Non-Disclosure Agreement from the Technical SupportEn gineer.
For University Use Only - Commercial Use Prohibited -
Page B-4 Append ix B
NOTES
Routing Your Technical Support Calls
Call
Customer question
Telephone Call Web Call
Tech SupportEngineer
creates a call in the database
Call is automatically created
in the database
Investigation Call Back and Investigation
Support Engineer
solves issue or
reports it
to Development (SPR)
SPRSoftware Performance Report
Software Performance Report (SPR)
SPR Verification through Tech. Support Engineer
Update CD to customer
SPR fixed from Development
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-5
NOTES
Technical Support Call Priorities
• Extremely Critical – Work stopped
• Critical – Work severely impacted
• Urgent – Work impacted
• Non Critical
• General Information
Software Performance Report Priorities
• Top Priority – Highly critical software issue that is causing a workstoppage.
• High – Critical software issue that affects immediate work and apractical alternative technique is not available.
• Medium – Software issue that does not affect immediate work or apractical alternative technique is available.
Registering for On-Line Support
To open a registration form, go to www.ptc.com/support,
click Sign-up Online, then enter your CONFIGURATION ID.
To find your CONFIGURATION ID, click Help > About Pro/ENGINEER.
Complete the information needed to identify yourself as a user. Note your
username and password for future reference.
For University Use Only - Commercial Use Prohibited -
Page B-6 Append ix B
NOTES
Using the Online Services
After you have registered, you will have full access to the online tools.
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-7
NOTES
Finding Answers in the Knowledge Base
The Technical Support KNOWLEDGE BASE contains over 18,000
documents.
Technical Application Notes (TANs), Technical Point of Interest (TPIs),
Frequently Asked Questions (FAQs), and Suggested Techniques offer up-to-
date information about all relevant software areas.
For University Use Only - Commercial Use Prohibited -
Page B-8 Append ix B
NOTES
Terminology Used by Technical Support
TAN – A Technical Application Note provides information about SPRs that
may affect more than just the customer originally reporting an issue. TANs
also may provide alternative techniques to allow a user to continue working.
TPI – A Technical Point of Interest provides additional technical
information about a software product. TPIs are created by Technical Support
to document the resolution of common issues reported in actual customer
calls. TPIs are similar to TANs, but do not reference an SPR.
Suggested Techniques – Provides step-by-step instructions including
screen snapshots, on how to use PTC software to complete common tasks.
FAQ – Frequently Asked Questions provides answers to many of the most
commonly asked questions compiled from the PTC Technical Support
database.
FAQs and Suggested Techniques are available in English, French, and
German.
Getting Up-To-Date Information
To subscribe to our KNOWLEDGE BASE MONITOR e-mail service, go to
www.ptc.com/support, and click Technical Support > Online Support
Applications > Knowledge Base Monitor. You will receive daily e-mail
with the latest information on your product.
Figure 1: Knowledge Base Monitor Sign Up
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-9
NOTES
CONTACT INFORMATION
Technical Support Worldwide Electronic Services
The following services are available 24 / 7:
• Web
� www.ptc.com/support/index.htm (Support)
� www.ptc.com/company/contacts/edserv.htm (Education)
� cs_ptc@ptc.com (for opening calls and sending data)
� cs-webmaster@ptc.com
(for suggestions about the Customer Service web site)
• FTP
• ftp.ptc.com (for transferring files to PTC Technical Support)
Technical Support Customer Feedback Line
The Customer Feedback Line is intended for general customer service
concerns that are not technical product issues.
� cs-feedback@ptc.com
• Telephone
� www.ptc.com/cs/doc/feedback_nums.htm
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Page B-10 Append ix B
NOTES
TELEPHONE AND FAX INFORMATION
For assistance with technical issues, contact the Electronic Services noted in
the previous section, or the Technical Support line as listed in the Telephone
and Fax Information sections below.
PTC has nine integrated Technical Support Call Centers in North America,
Europe, and Asia. Our worldwide coverage ensures telephone access to
Technical Support for customers in all time zones and in local languages.
North America Telephone Information
Customer Services (including Technical Support, License Management, and
Documentation Requests):
• Within the United States and Canada
� 800-477-6435
• Outside the United States and Canada:
� 781-370-5332
� 781-370-5513
• Maintenance
� 888-782-3774
• Education
� 888-782-3773
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-11
NOTES
Europe Telephone Information
Technical Support Telephone Numbers
• Austria
� 0800 29 7542
• Belgium
� 0800-15-241 (French)
� 0800-72567 (Dutch)
• Denmark
� 08001-5593
• Finland
� 0800-117092
• France
� 0800-14-19-52
• Germany
� 0180-2245132
� 49-89-32106-111 (for Pro/MECHANICA® outside of
Germany)
• Ireland
� 1-800-409-1622
• Israel
� 1-800-945-42-95 (All languages including Hebrew)
� 77-150-21-34 (English only)
• Italy
� 0800-79-05-33
• Luxembourg
� 0800-23-50
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Page B-12 Append ix B
NOTES
• Netherlands
� 0800022-4519
• Norway
� 8001-1872
• Portugal
� 05-05-33-73-69
• South Africa
� 0800-991068
• Spain
� 900-95-33-39
• Sweden
� 020-791484
• Switzerland
� 0800-55-38-33 (French)
� 0800-83-75-58 (Italian)
� 0800-552428 (German)
• United Kingdom
� 0800-318677
License Management Telephone Numbers
• Belgium
� 0800-75376
• Denmark
� 8001-5593
• Finland
� 0800-117-092
• Eastern Europe
� 44 1252 817 078
• France
� 0800-14-19-52
• Germany
� 49 (0) 89-32106-0
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-13
NOTES
• Ireland
� 1-800-409-1622
• Italy
� 39 (0) 39-65651
• Netherlands
� 0800-022-0543
• Norway
� 8001-1872
• Portugal
� 05-05-33-73-69
• Russia
� 44 1252 817 078
• Spain
� 900-95-33-39
• Sweden
� 020-791484
• Switzerland
� 41 (0) 1-8-24-34-44
• United Kingdom
� 0800-31-8677
For University Use Only - Commercial Use Prohibited -
Page B-14 Append ix B
NOTES
Education Services Telephone Numbers
• Benelux
� 31-73-644-2705
• France
� 33-1-69-33-65-50
• Germany
� 49 (0) 89-32106-325
• Italy
� 39-039-65-65-652
� 39-039-6565-1
• Spain/Portugal
� 34-91-452-01-00
• Sweden
� 46-8-590-956-00 (Malmo)
� 46-8-590-956-46 (Upplands Vasby)
• Switzerland
� 41 (0) 1-820-00-80
• United Kingdom
� 44-0800-212-565 (toll free within UK)
� 44-1252-817-140
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-15
NOTES
Asia and Pacific Rim Telephone Information
Technical Support Telephone Numbers
• Australia
� 1800-553-565
• China*
� 10800-650-8185 (international toll free)
� 108-657 (manual toll free)
• Hong Kong
� 800-933309
• India*
� 000-6517
• Indonesia
� 001-803-65-7250
� 7-2-48-55-00-35
• Japan
� 120-20-9023
• Malaysia
� 1-800-80-1026
• New Zealand
� 0800-44-4376
• Philippines
� 1800-1-651-0176
• Singapore
� 65-830-9899
• South Korea
� 00798-65-1-7078 (international toll free)
� 080-3469-001 (domestic toll free)
For University Use Only - Commercial Use Prohibited -
Page B-16 Append ix B
NOTES
• Taiwan
� 0080-65-1256 (international toll free)
� 080-013069 (domestic toll free)
• Thailand
� 001-800-65-6213
Callers dialing from India or China must provide the operator with the
respective string:
• China
� MTF8309729
• India
� MTF8309752
The operator will then connect you to the Singapore Technical Support
Center.
License Management Telephone Numbers
• Japan
� 81 (0) 3-3346-8280
• Hong Kong
� (852) 2802-8982
Education Services Telephone Numbers
• Australia
� 61 2 9955 2833 (Sydney)
� 61 3 9561 4111 (Melbourne)
• China
� 86-20-87554426 (GuangZhou)
� 86-21-62785080 (Shanghai)
� 86-10-65908699 (Beijing)
• Hong Kong
� 852-28028982
• India
For University Use Only - Commercial Use Prohibited -
Custom er Support In fo rmat ion Page B-17
NOTES
� 91-80-2267272 Ext.#306 (Bangalore)
� 91-11-6474701 (New Delhi)
� 91-226513152 (Mumbai)
• Japan
� 81-3-3346-8268
• Malaysia
� 03-754 8198
For University Use Only - Commercial Use Prohibited -
Page B-18 Append ix B
NOTES
• Singapore
� 65-8309866
• South Korea
� 82-2-3469-1080
• Taiwan
� 886-2-758-8600 (Taipei)
� 886-4-3103311 (Taichung)
� 886-7-3323211 (Kaohsiung)
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