Mechanical Nonlin 13.0 WS 06A Creep
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Transcript of Mechanical Nonlin 13.0 WS 06A Creep
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8/12/2019 Mechanical Nonlin 13.0 WS 06A Creep
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Customer Training Material
or s op
Stress Relaxation
Structural Nonlinearities
WS6A-1ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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8/12/2019 Mechanical Nonlin 13.0 WS 06A Creep
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ANSYS Mechanical Structural Nonlinearities
Customer Training MaterialWorkshop 6A: Stress Relaxation
Goal
Predict rate dependent stress relaxation of structure using an implicit time
hardening implicit creep model.
Model Description
C-Clamp assembly consisting of a
C-Clamp
tetrahedral elements to represent
the clamp and a line body meshed
with beam elements to represent
the bolt
Bolt tied to the clamp body via
fixed joints at each end.
Bolt
Rate dependent structural steel for
clamp
High strength rate independent
WS6A-2ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
steel for bolt
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Model Description (contd)
Materials:
Bolt: Rate independent structural steel
Clamp: Rate dependent structural steel that relaxes according to the following
Modified Time Hardening formula:
1
1
432
+
=
+
C
etC
cr
Where: C1 = 2e-10, C2=1, C3=1.5, C4 = 0, metric units (N, mm)
Load specifications:
10,000N bolt pretension loading for 150 seconds
WS6A-3ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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8/12/2019 Mechanical Nonlin 13.0 WS 06A Creep
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ANSYS Mechanical Structural Nonlinearities
Customer Training MaterialWorkshop 6A: Stress Relaxation
Steps to Follow:
Restore Archive browse for file W6a-creep.wbpz
Save as
File name: W6a-creep
*
WS6A-4ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
The project Schematic should look like the
picture to the right.
From this Schematic, you can see that Engineering
defined (green check marks). It remains to define the rate dependent creep
material properties, set up and run the FE model in
ec an ca
Hi hli ht the En ineerin Data Cell and o en b
clicking on the Right Mouse Button (RMB)=>Edit.
Verify that the units are in Metric(Tonne,mm,..)
system. If not, fix this by clicking on
, ,..
WS6A-5ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Define the creep material model
Highlight the Default Structural
Steel material and RMB=>Duplicate
to create a se arate material model.
Rename this new material Creep
With the new Creep material
,
and insert a Modified Time
Hardening creep model from the
Creep folder.
The Engineering Data page should
now look as shown
WS6A-6ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Define the creep material model (contd)
Set the Reference Length Unit to mm
Using the constant values from page WS6A-3 fill in the data table accordingly
WS6A-7ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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8/12/2019 Mechanical Nonlin 13.0 WS 06A Creep
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
e urn o e ro ec c ema c
Refresh project
Double click on the Model ell to open the FE Model Mechanical
Session) (or RMB=>Edit)
WS6A-8ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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8/12/2019 Mechanical Nonlin 13.0 WS 06A Creep
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Once inside the Mechanical application, verify the working unit system
Unit > Metric (mm,kg,N,s,mV,mA)
Open the folders beneath the model branch to become familiar with the
- .
Expand Geometry branch and note the two different body types (solid body forthe clamp, line body for the bolt).
Expand the Connections branch and note the two fixed joints designed to connect
the ends of the bolt to the faces of the clamp by way of constraint equations
automatically. The pinball is sized to represent the extent of bolt head and nut
interface with the clamped surfaces.
WS6A-9ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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8/12/2019 Mechanical Nonlin 13.0 WS 06A Creep
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Highlight the Solid body representing the clamp and change material
assignment to the Creep model
WS6A-10ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Loads and Boundary conditions.
The back face of the clamp body is fixed.
A bolt pretension load is applied to the line body over two load steps
load
LS2 locks the adjustment into the bolt via constraint equations .
WS6A-11ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Highlight the Analysis Settings branch,set number of load steps to 2 and
define the Solution Control specifications as shown for each load step.
Note:
-
with the Creep Effects turned Off. LS2 activates the creep calculation (end time =150 s) over several substeps,
allowing bisections if/when creep strain exceeds 10 times the elastic strain.
WS6A-12ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010
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ANSYS Mechanical Structural Nonlinearities
Customer Training Material Workshop 6A: Stress Relaxation
Execute the solve
This run should converge without trouble,
but might take a few minutes depending on
hardware.
Note the development in creep strain as
indicated by nonzero values reported for
creep ratio in the solver output during the
.
After Solution is complete, Post process
results (displacement, stress, strain,etc)
Insert Equivalent Creep Strain
Notice how the Equivalent Creep Strain
increases (as expected) over time, while the
the structure relaxes.
Animate various results over time to confirm
these effects.
WS6A-13ANSYS, Inc. Proprietary
2010 ANSYS, Inc. All rights reserved.Release 13.0
December 2010