NAS120, Workshop 11, November 2003 WS11-1 WORKSHOP 11 SPACECRAFT FAIRING.

NAS120, Workshop 11, November 2003 WS11-1

WORKSHOP 11

SPACECRAFT FAIRING

WS11-2NAS120, Workshop 11, November 2003


Problem Description In this exercise, a spacecraft fairing will be constructed. Curves and

surfaces will be used to define the fairing geometry. The finite element model will consist of 2-dimensional elements with 1-dimensional elements applied at various edges of the geometry. The 1-dimensional elements will represent stiffeners for the structure.


Workshop Objectives Learn to use Groups and Lists


Suggested Exercise Steps1. Create a new database called fairing.db and set the model preferences.

2. Create the model geometry.

3. Create the mesh seeds for the model.

4. IsoMesh the model using Quad4 topology.

5. Check the free edges, equivalence the model, and then check the free edges again.

6. Create a new group called FEM that contains only the finite elemental model. Then post only the FEM group.

7. Create two material properties, alum_1 and alum_2.

8. Create two fields, one for temperature and the other for thickness.

9. Create element properties.

10. Create a temperature boundary condition.

11. Create a series of lists containing elements that satisfy these following requirements: 1) the elements are made up of the alum_1 material, 2) the elements are greater than 0.98 in thickness, and 3) the elements have a temperature greater than 230.0 degrees.

12. Intersect lists a and b to produce a list of elements that satisfy the first two conditions.


Suggested Exercise Steps (Cont.)13. Create another list that satisfies the third condition.

14. Intersect the new list with the other list to produce a group of elements that satisfy all three conditions. Then, place these elements in a separate group.

15. Post the group containing the elements produced in step 14.

16. Create 2 new groups, each containing elements with different property sets.

17. Change the display attributes for each group.

18. Post each group separately, then post both groups together.


Step 1. Create New Database

Create a new database and set the

model preferences.

a. File : New.

b. Enter fairing for the File Name.

c. Click OK.

d. Set the Tolerance to Default.

e. Make sure that the Analysis Code

and Analysis Type are set to

MSC.Nastran and Structural,

respectively.

f. Click OK.

a

b c

d

e

f


Step 2. Create Model Geometry

Create the points and curves that

represent the outline of the fairing.

a. Geometry : Create / Point / XYZ.

b. Enter [30 0 0] under Point

Coordinates List and click

Apply.

c. Geometry : Create / Curve / XYZ.

d. Enter <0 120 0> and [50 40 0]

under Vector Coordinates List

and Origin Coordinates List,

respectively.

e. Click Apply.

f. Click on Show Labels icon.

g. Click on Point Size icon to

increase the point size.

h. Geometry : Create / Curve / Point.

i. Click on Point 1 under Starting

Point List and click on Point 2 for

Ending Point List.

j. Click Apply.

a

b

c

d

e

h

i

j

f g


Step 2. Create Model Geometry (Cont.)

Illustrated here are curves that represent the basic geometry for the fairing. These curves will be revolved 360º in order to get the final model.



Create the fairing by revolving

curves 1 and 2 about the fairing’s

vertical center line.

a. Geometry : Create /

Surface / Revolve.

b. Enter Coord 0.2 for Axis

c. Enter 360 for the Total

Angle.

d. Click on Curve 1, then click

on Curve 2.

e. Viewing : Angles.

f. Enter 30 0 0 under Angles.

g. Click Apply.

a

b

c

d

e

f

g



Change the display preferences

in order to get a clearer visual of

the model.

a. Display : Geometry…

b. Enter 3 for Number of

Display Lines

c. Click Apply, then Cancel.

a

b

c


Step 3. Create Mesh Seeds

Create a finite element mesh

so that 4 node Quad elements

are created every 10° along the

circumferential edges.

a. Elements : Create / Mesh

Seed / Uniform.

b. Select Number of

Elements and enter 36

for the Number.

c. Select the top

circumferential edge of

the fairing(Surface 1.3).

a

b

c


Step 3. Create Mesh Seeds (Cont.)

In the vertical direction (y-direction),

define a smoothly transitioning mesh

density. The elements along the top of

the cylinder are 2.5 times as large as

those along the bottom edge (tapered

end) of the fairing.

a. Elements : Create / Mesh Seed /

One Way Bias.

b. Select L1 and L2 and enter 7 and

10 for L1 and L2, respectively.

c. Select Curve 1.

d. Elements : Create / Mesh Seed /

One Way Bias.

e. Select L1 and L2 and enter 4 and

7 for L1 and L2, respectively.

f. Select Curve 2.

a

c

b

d

e

f


Step 4. Create a Mesh for the Model

Now that the mesh seeds have

been created, mesh the model

using Quad4 topology.

a. Elements : Create / Mesh

/ Surface.

b. Select Quad, IsoMesh,

and Quad4.

c. Rectangular pick the

entire model and click

Apply.

d. Remove the display lines

by clicking the on the

Display lines icon.

e. Remove the labels by

clicking the Hide labels

icon.

f. Decrease the point-size

by clicking on the Point

Size icon.

a

b

c

e df


Step 4. Create a Mesh for the Model (Cont.)

Mesh the horizontal (circumferential)

edges of each surface with two-

noded bar elements.

a. Click on Plot/Erase icon and

click on Erase under FEM.

b. Click OK.

c. Elements : Create / Mesh /

Curve.

d. Set Topology to Bar2

e. Shift select the 3 curves (as

indicated).

f. Click Apply. b

c

d

e

f

a

e


Step 5. Observe the Free Edges

Check the free edges of the model,

equivalence, and then check the

free edges again.

a. Click on the Plot/Erase Icon.

b. Under FEM, click Plot.

c. Elements : Verify / Element /

Boundaries.

d. Select Free Edges under

Display Type.

e. Click Apply.

f. Elements : Equivalence / All /

Tolerance Cube.

g. Click Apply.

h. Repeat steps c through e.

c

d

e

f

g

a


Step 6. Create a New Group

Replot the FEM and create a group

called FEM containing only the finite

element model. Post only this new

group to the viewport.

a. Group : Create…

b. Enter FEM for the New Group

Name.

c. Select Unpost All Other

Groups.

d. Change Group Contents to

Add All FEM.

e. Click Apply.

a

b

c

d

e


Step 7. Create Material Properties

Create the first material for the

model. Material alum_1 will be

applied to the top(cylindrical) portion

of the fairing.

a. Materials : Create / Isotropic /

Manual Input.

b. Enter alum_1 for the Material

Name.

c. Click on Input Properties.

d. Select Linear Elastic and

enter 1.05E7, 0.33, and

2.6E-4, for Elastic Modulus,

Poisson Ratio, and Density,

respectively.

e. Click OK.

f. Click Apply.

a

b

c

d

ef


Step 7. Create Material Properties (Cont.)

Create the second material for the

model. Material alum_2 will be

applied to the bottom(tapered)

portion of the fairing.

a. Materials : Create / Isotropic /

Manual Input.

b. Enter alum_2 for the Material

Name.


d. Select Linear Elastic and

enter 1.18E7, 0.33, and

2.4E-4, for Elastic Modulus,

Poisson Ratio, and Density,

respectively.

e. Click OK.

f. Click Apply.

a

b

c

d

ef


Step 8. Create Fields

Define a field that represents the

varying thickness.

a. Fields : Create / Spatial / PCL

Function.

b. Enter thickness for the Field

Name.

c. Enter 1.5-’Y/160 for the Scalar

Function and click Apply.

a

b

c



Plot the function defined in the field.

A. Field : Show

B. Select thickness as the field to show.

C. Click Specify Range.

D. Enter 160.0 for the maximum and 20 for the number of points.

E. Click O.K.

F. Click Apply.

a

bd

e c

f



Delete the plot.

A. XY Plot : Delete / XYWindow

B. Select XY Result Window.

C. Click Apply.

D. Choose Yes to delete the result window.

a

b

c

d


Define a field that represents the

varying temperature distribution.

a. Fields : Create / Spatial / PCL

Function.

b. Enter temperature for the

Field Name.

c. Enter 200.0-(150.0/160.0)*’X

for the Scalar Function and

click Apply.


a

b

c



Plot the function defined in the field.

A. Field : Show

B. Select temperature as the field to show.

C. Click Specify Range.

D. Enter 50.0 for the maximum and 10 for the number of points.

E. Click O.K.

F. Click Apply.

bd

e c

a

f


Step 9. Create Element Properties

Create two element properties

which include the material

definitions and varying thickness.

a. Properties : Create / 2D /

Shell.

b. Enter prop_1 for the

Property Set Name.


d. Click on the Select

Material icon.

e. Select alum_1 from the

Select Material list box.

f. Click on the Front view

icon.

f

a

b

c

d

e


Step 9. Create Element Properties (Cont.)

Finish creating the first property set.

a. Set the thickness type to

Element Nodal and click on

the Select Field icon.

b. Select thickness as the Scalar

Spatial Field.

c. Click OK.

d. Click on Select Members and

click on the Shell Element

icon.

e. Select the top(cylindrical)

portion of the fairing by

dragging a box around the

desired section (as indicated

on next page).

f. Click Add, then Apply.

a

e

d

f

b

c



Illustrated here is the desired application region for the first property set.



Create the second property set.

a. Properties : Create / 2D /

Shell.

b. Enter prop_2 for the Property

Set Name.

c. Click on Input Properties…

d. Click on the Select Material

Icon.

e. Select alum_2 from the

Existing Materials.

f. Click on the Select Field Icon

g. Select thickness from the

Existing Fields box.

h. Click OK.

i. Click on Select Members and

select the bottom(tapered)

portion of the fairing by

dragging a box around it(as

indicated on next page).

j. Click Add, then Apply.

a

b

c

d

f

i

j

eg

h



Shown here are the elements for the desired application region of the second property set.


Step 10. Create Temperature Boundary Conditions

Define the model’s varying temperature

distribution.

a. Loads/BCs : Create / Temperature

/ Nodal.

b. Enter temp for the New Set

Name.

c. Click on Input Data.

d. Click on Temperature and select

temperature from the Spatial

Fields.

e. Click OK.

f. Click on Select Application

Region.

g. Under Geometry Filter, select

FEM.

h. Click on Application Region and

select the entire model.

i. Click Add, then, OK

j. Click Apply.

a

b

c

d

e

f

g

h

i

j


Step 10. Create Temperature Boundary Conditions (Cont.)

Turn off the temperature labels in

order to get a better visualization of

the model.

a. Display : Load/BC/Elem.

Prop…

b. Under Loads/BC’s remove

check under Temperature.

c. Click Apply, then Cancel.

a

b

c


Step 11. Create Lists

Use Lists and groups to filter then group

the quad elements that have the following

attributes:

Material : alum_1

Thickness : > 0.98

Temperature : >230.0

a. Tools : List / Create…

b. FEM / Element / Attribute

c. Under Attribute, select Material.

d. Under Existing Materials, select

alum_1.

e. Set the Target List to “A” and click

Apply.

a

b

c

d

e

The contents of List A compose of elements that satisfy the first condition; they are made up of the alum_1 material.


Step 11. Create Lists (Cont.)

Define List B to include only the

Quad elements that have a

thickness greater than 0.98.

a. Properties : Show.

b. Under Existing Properties,

select Thickness.

c. Set Display Method to

Scalar Plot.

d. Select Current Viewport,

select FEM and click Apply.

a

b

c

d

Shown above is a fringe plot the model by thickness. Those elements that are thicker than 0.98 will be included in the next list.


Step 11. Create Lists (Cont.)

After defining the list parameters,

add the elements greater than 0.98

in thickness to list B.

a. Tools : List / Create…

b. FEM / Element / Attribute.

c. Under Attribute, select Fringe

Value.

d. Under Fringe Tools, select

default_Fringe.

e. Change the inequality to > and

enter 0.98.

f. Select “B” for the Target List.

g. Click on Apply.

a

b

c

d

e

f

g

The contents of List B include all elements thicker than 0.98.


Step 12. Intersect Lists

Intersect Lists A and B and replace

the contents of List A with the

elements found in the intersection.

a. Tools : List / Boolean…

b. Click on the Intersect icon.

c. Click on Replace A.

The new List A is composed of elements that satisfy both requirements: they are made up of alum

a

b

c


Step 13. Create More Lists

Perform a final classification of the

elements. Isolate those elements

that satisfy the third condition of the

applied temperature load > 230.0.

a. Loads/BCs : Plot Contours /

Temperature.

b. Select temp from the

Existing Sets.

c. Select Temperature under

Select Data Variable.

d. Select the FEM group and

click Apply.

a

b

c

d


Step 13. Create More Lists (Cont.)

Clear the contents of List B and add the

values obtained from the final classification.

a. Tools : List / Create.

b. FEM / Element / Attribute.

c. Select Fringe Value and

default_Fringe for Attribute and

Fringe Tools respectively.

d. Change the inequality to > and enter

230.0.

e. Select “B” for the Target List.

f. Click on Clear on the List B form

g. Click Apply on the List Create

form.

a

b

c

d

e

f

g


Step 14. Intersect Lists Again

Lists A and B will be intersected

again to create a List C. This list will

contain the elements that satisfy all

three conditions. The contents of

List C will then be placed into a new

group called common_quads.

a. Tools : List / Boolean…

b. Click Clear.

c. Click on the Intersect icon(It

may be necessary to click on

any of the other icons first).

d. Click on Add To Group…

e. Enter common_quads for the

Group Name.

f. Click Apply, then Cancel.

a

b

c

d e

f


Step 15. Post Group

Post the common_quad group.

This is the group of elements

that satisfy all three of the

conditions defined earlier.

a. Group : Post…

b. Select the

common_quads group

under Select Groups to

Post.

c. Click Apply, then

Cancel.

d. Click on the Iso 1 view

icon.

a

b

c

d


Step 15. Post Group (Cont.)

This is the Iso 1 view of the elements in the common_quads group. These are all the elements that satisfied all three conditions.


Step 16. Create Two New Groups

Create two new groups, prop1_group

and prop2_group. Then, change the

display attributes for each group.

a. Click on the Reset Graphics

icon.

b. Group : Create…

c. Create / Property Set.

d. Enter prop1_group for the

Group Name.

e. Select prop_1 under Property

Sets.

f. Click Apply.

g. Repeat steps b through f

entering prop2_group for the

Group Name and selecting

prop_2 under Property Sets.

a

b

c

d

e

f

f


Step 17. Change the Display Attributes

Set the entity coloring and labeling to Group mode

and then change the display attributes for each of

the two new groups.

a. Display : Entity / Color / Label / Render…

b. Select Group under Entity Color and

Labeling.

c. Select the prop1_group under the Target

Group(s).

d. Select HiddenLine for the Render Style

and select dark blue for the Shade Color.

e. Click Apply.

f. Select the prop2_group for the Target

Group(s).

g. Select Wireframe for the Render Style and

select red for the Shade Color.

h. Click Apply, then, Cancel.

a

b

c

d

e

f

g

h


Step 18. Post Groups

Change views and post the

prop1_group.

a. Click on the Iso 3 view icon.

b. Group : Post…

c. Under Select Groups to

Post, select

prop1_group.

d. Click Apply.

a

b

c

d


Step 18. Post Groups (Cont.)

Post only the prop2_group.

a. Group : Post…

b. Under Select Groups to

Post, select

prop2_group.

c. Click Apply.

a

b

c


Step 18. Post Groups (Cont.)

Post both the prop1_group

and the prop2_group.

a. Group : Post…

b. Under Select

Groups to Post,

select both

prop1_group

and

prop2_group.

c. Click Apply.

a

b

c

NAS120, Workshop 11, November 2003 WS11-1 WORKSHOP 11 SPACECRAFT FAIRING.

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Transcript of NAS120, Workshop 11, November 2003 WS11-1 WORKSHOP 11 SPACECRAFT FAIRING.