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3-1
C H A P T E R 3
Working Model FEA: SolidWorksExercises
This chapter presents simulation exercises designed to help you getstarted with Working Model FEA. The exercises are for the followingproducts:
Working Model FEA: SolidWorks
Working Model 4D
The exercises make use of the Simulation Wizards as well as theWorking Model FEA standard menus to set up the problems, submit thesimulation to analysis, solve the models, and evaluate results.
Exercise 3.1 uses the Stress Wizard to perform stress simulation ona bracket.
Exercise 3.2 uses Working Model Shape Optimization to optimize abracket design.
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Exercise 3.1 Stress Simulation on a Bracket 3-2
Exercise 3.1 Stress Simulation on a Bracket
Figure 3-1
Choosing the Stress Wizard
This exercise introduces you to the Working Model FEA stress analysisfeature. You will use the Stress Wizard to determine the failure stresses(von Mises stresses) generated in the object as a result of an appliedpressure. You will then calculate the factor of safety based on von Misesstresses (minimum acceptable factor of safety=1). The Stress Wizardleads you through the entire simulation process.
Getting Started
In this section you will open the bracket file in SolidWorks and launchthe Stress wizard.
From S olidWorks:
1. Choose Open from the File menu.
This displays the File Open dialog.
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3-3 Chapter 3Working Model FEA: SolidWorks Exercises
2. Browse the Tutorial folder Chapter 3\Exercise 3.1 and open the
Bracket.par file
This opens and displays the Bracket as shown in Figure 3-1.
Note: The default location for the Tutorials folder is ProgramFiles\Working Model
3. Choose Wizards from the Working Model FEA menu, thenchoose Stress Wizard from the Wizards submenu.
This launches the Stress Wizard as shown in Figure 3-2.
Figure 3-2
Stress Wizard
Defining the Problem and Units
In this section you will define the problem for the Stress Wizard.
1. Click Begin to initiate the simulation process.
2. Click Define.
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Exercise 3.1 Stress Simulation on a Bracket 3-4
The Wizard creates a simulation model with a default name. The
default is the name of your part with the word Model appended.
Figure 3-3
Simulation ModelName Window
3. Click Next.
This displays the Units tab of the Stress Wizard.
4. Click Units.
This displays the Desired Units window as shown in Figure 3-4.
Since you already specified inches, the units default to the English
system.
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Figure 3-4
Desired Units Window
5. Click Finish and go to the next step.
Specifying Loads
In this section you will specify a load for the stress simulation. InWorking Model FEA, loads are grouped into named sets that can containone or more loads.
1. Click the Loads tab on the Stress Wizard window.
This displays a window that prompts you to accept a default name
for the load set.
2. Click Next.
This displays the How Loads are Applied window as shown in
Figure 3-5.
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Exercise 3.1 Stress Simulation on a Bracket 3-6
Figure 3-5
How Loads AreApplied Window
3. Select Face and click Next.
In this problem the load is pressure, which is applied on a face.
4. Optionally click Change View.
If you need to zoom, rotate, or pan the view before you pick the face,
click the Change View button. This allows you to access the
Desktop View menu or toolbar commands and modify the view as
needed. Click OK when you are finished with view modifications.
5. Click Next.
This displays the Load Geometry window.
6. Click on the top face of the base portion of the bracket. Be sure
the correct face is selected. (You can right-mouse click to selectfaces.)
7. Click Pressure (the load type) and then click Next.
This displays the Load Value dialog.
8. Enter a load value of 50.
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Pressure has a single component perpendicular to the face.
Pressure is positive if it is pointing at the face.
9. Click Next in the Load Value dialog.
This displays the Symbol Data dialog. It lets you control the color
and size of the load symbols.
Force symbols will appear on the geometry, as shown in Figure 3-
6. A dialog prompts you to create another load.
Figure 3-6
Force Symbols onBracket Face
10. Click Finish and go to the next step.
Specifying Restraints
In this section you will specify a restraint for the stress simulation. InWorking Model FEA, restraints are grouped in named sets.
1. Click the Restraints tab on the Stress Wizard window.
This displays a window that prompts you to accept a default name
for the load set. The default load set name is Ex1_brkt_RS.
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Exercise 3.1 Stress Simulation on a Bracket 3-8
2. Click Next.
This displays the Restraints window as shown in Figure 3-7.
Figure 3-7
How RestraintsAre Applied Window
3. Select Face and click Next.
In this problem the restraint is applied on the face.
4. Click on the back vertical face of the bracket. Be sure the back
vertical face is selected.
5. Click Next.
This displays the Restraint Types window as shown in Figure 3-8.
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Figure 3-8
Restraints Types Window
6. Select Fixed in the Restraint Type window and click Next.
This prevents the back of the bracket from moving or rotating in any
direction. The Wizard displays the Symbol Data dialog, which lets
you control the color and size of the Restraint symbols.
7. Change the symbol size to 0.5 inches and click Next in the
Symbol Data dialog.
Force symbols will appear on the geometry, as shown in Figure 3-
9. A dialog prompts you to create another restraint.
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Exercise 3.1 Stress Simulation on a Bracket 3-10
Figure 3-9
Restraints and Loads
on Bracket
8. Click Finish and go to the next step.
Specifying Mesh and Getting Results
In this section you will analyze your model to get results. You will firstspecify a mesh for the stress simulation. In Working Model FEA thematerial used for analyzing the model is actually assigned to the mesh.
1. Click the Analyze tab on the Stress Wizard window and select
Analyze.
This displays the Materials for Mesh dialog.
2. Select Choose an existing material and click Next.
This displays the Select Existing Material for Mesh window as
shown in Figure 3-10.
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Figure 3-10
Select Existing Material
or Mesh Window
3. Scroll the material list to display Steel-ANSI 304. Select it and
then click Next.
You are now ready to select the geometry to mesh.
4. Click Next.
This displays the Analysis Execution window, which specifies the
analysis start time.
There is an abrupt geometric change where the top edge of the rib
joins the vertical part of the bracket and this is likely to cause higher
stress concentrations. To get a better picture of the stresses there,
you need a fine mesh in that area. To save meshing and analysis
time, it is better to specify larger elements in most of the body andapply mesh refinements in the critical areas than to use small
elements overall. For this reason, we will use h-adaptivity.
5. Select h-adaptivity.
Use default values for Map Iterations and Target Error.
6. Accept Now and Click Finish to submit the model.
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Exercise 3.1 Stress Simulation on a Bracket 3-12
The program will first display a Working Model dialog that shows
the progress of the Meshing process. Then the MSC.Nastran dialog
(Figure 3-11) displays the progress of the analysis process.
Figure 3-11
MSC.Nastran Dialog
When the first iteration is complete, the program will refine the mesh
where necessary to achieve the most accurate results. It will iterate
several times until it reaches your desired accuracy setting. When
the analysis is completed, the window displays: Analysis job
completed successfully.
Working Model FEA calculates an extensive range of analysis
solutions. The Wizard, however, returns only those responses that
can give you the quickest visual and numerical feedback about the
success or failure of your part. For more comprehensive results you
must use the dialogs activated by the Working Model FEA menu.
These will be shown in other exercises.
Using the Design Doctor to Analyze Results
The Design Doctor is an analysis expert designated to examine andinterpret your analysis results. The Design Doctor checks aspects of youranalysis results against various pre-established criteria and tells you whatto correct should any of your results fail the test. Sometimes the DesignDoctor can make the necessary repairs to your simulation data.
1. Click Results in the Stress Wizard window.
This displays the Design Doctor window as shown in Figure 3-12.
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Figure 3-12
Design Doctor
2. Click Next.
The Design Doctor displays the list of criteria against which your
results will be tested (Figure 3-13).
Figure 3-13
Design Doctor Options
3. Enter the minimum factor of safety value you consider
acceptable for your design.
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Exercise 3.1 Stress Simulation on a Bracket 3-14
Working Model FEA will obtain the maximum yield stress of the
material from the material library and get the von Mises stresses
from the analysis results.
4. Click Next.
The Design Doctor will proceed with the diagnostic tests for each
criteria. If the results pass the test, the Design Doctor puts a check
mark next to the criteria name. The dialog below (Figure 3-14)
shows that all tests have completed successfully.
Figure 3-14
Design Doctor Results
To get more details from the Design Doctor:
5. Highlight Design Intent/Animation and then click Diagnosis.
This displays the diagnosis for the Design Intent.
6. Click Close, Finish, and Close to end the exercise.
You have completed this exercise.
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Exercise 3.2 Optimizing the Shape of a Bracket
This exercise introduces you to shape optimization and Working ModelShape. The Optimization Wizard will lead you through the sequence ofsteps required to optimize the design of a bracket.
Using Working Model Shape Optimization
Working Model Shape Optimization links finite element analysis and
parametric geometric construction in a process called shapeoptimization. Shape optimization automates the search for an optimaldesign by varying dimensions to achieve a design objective, for example,minimum mass, while observing certain design criteria, such asmaximum allowable stress limits.
Working Model Shape Optimization must be used with Stress, Vibration,or Buckling Simulations. The following is a short outline of the
optimization strategy. You will see each step in greater detail as youwork your way through the exercise in this section.
7. Start with your SolidWorks part geometry. Identify the dimensions
that you will vary. Define the global design variables in Solid-
Works.
8. Create a simulation model of the appropriate analysis type. Add
loads (except in aVibration Simulation), restraints, and mesh. Run
the analysis of this model if you need to simulate the behavior of
the part with its initial dimensions.
9. Define a shape optimization model and associate with it the follow-
ing input criteria:
Design ObjectiveThe goal of the optimization process. Acommon design objective is to minimize the mass of the part
Design VariablesIdentified dimensional parameters that arepermitted to change during the optimization process
Design constraintsPhysical characteristics and responsesthat must be maintained (e.g., maximum allowable stress ordisplacement)
10. Run the shape optimization analysis.
11. Review the shape optimization results and observe the sensitivity of
the overall design to each variable.
12. Update the SolidWorks part based on the new optimized dimen-
sions.
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Exercise 3.2 Optimizing the Shape of a Bracket 3-16
Preparing the Part
Open a Part The part for this example is in Tutorials\Chapter 3\Exercise 3.2. Thename of this part is Bracket_opt.par.
Define the DesignVariable(s)
For this exercise, we have already defined the design variables. Designvariables are defined in SolidWorks as Independent Global DesignVariables. The equation field should contain the value with which thegeometry was constructed.
Associate DesignVariables and Dimensions
In this exercise, the design variables are already associated with thedimensions. Design variables and dimensions are associated through theSolidWorks Part menu. Choose Edit Feature to associate the variableswith the dimensions.
Figure 3-15
Bracket
The design variables and dimensions for the bracket shown in Figure 3-15 are as follows:
Unit systemEnglish
Load2500 lbf total force pushing down on the top face of the baseportion of the bracket.
RestraintThe back face of the bracket is fully restrained.
MaterialStainless Steel
Design ObjectiveMinimize the mass of the part by changing thethickness of the base and of the rib. Initial mass= 26.5 lbm.
Design ConstraintAllowable von Mises stress = 38000 psi.
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Design VariablesTwo dimensions of the bracket will serve asdesign variables:
Base thicknessInitial value = 1.0 in (Minimum value allowed =0.1 in./Maximum value allowed = 1.1 in.)
Rib thicknessInitial value=0.75 in (Minimum value allowed= 0.1in./Maximum value allowed=1.0 in)
Getting Started
In this section you will open the bracket file and define the simulationmodel required for optimization. If you need help with these steps, please
refer to the first exercise in this chapter.
From S olidWorks:
1. Choose Open from the File menu.
This displays the File Open dialog.
2. Browse the Tutorials\Chapter 3\Exercise 3.2 folder and open the
bracket_opt.par file.
This opens and displays the Bracket as shown in Figure 3-15.
Note: The default location for the Tutorials folder is ProgramFiles\Working Model
3. Create a new simulation model, load set, and restraint set.
See Exercise 3.1 for help with these steps.
The simulation type is Stress. Use the following parameters:
Loads Total Force2500 lbf in the Global Y direction on the top face of thebase portion of the bracket.
Restraints Fully restrain the back face of the bracket.
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Exercise 3.2 Optimizing the Shape of a Bracket 3-18
Mesh MaterialSteelElement Size Accept the default
Figure 3-16
The Simulation Model
4. Choose Wizards from the Working Model FEA menu and then
choose Working Model Shape Wizard from the Wizards
submenu.
5. Click Begin, then Define.
6. Accept Start a New Model and click Next.
The Model Name and Simulation Model page as shown in Figure 3-
17is displayed.
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3-19 Chapter 3Working Model FEA: SolidWorks Exercises
Figure 3-17
Model Name and
Simulation Model Page
7. Accept the default Optimization Model Name and the Simulation
Model Name.
8. Click Finish and continue with the next section.
Specifying a Design Objective
Before you can optimize a designs performance or response, you mustdefine what it is that you consider optimal. It may be a minimum mass,maximum first natural frequency, etc. Whatever you choose, this will be
the design goal, or objective. For this project, the design objective is tominimize the mass of the part.
1. Click the Objective tab in the Wizard window.
This displays the Design Objective page as shown in Figure 3-18.
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Exercise 3.2 Optimizing the Shape of a Bracket 3-20
Figure 3-18
Design Objective Page
2. Accept the default design objective action as Minimize and the
default design objective response as mass.
3. Click Finish and continue with the next section.
Specifying Design Variables
In this step you will identify the design variables. Working Model Shapeenters the initial value of a predefined variable dimension and specifiesdefault maximum and minimum allowable boundaries (+/- 10%). Youcan modify these boundary values to suit your optimization criteria.
1. Click the Variables tab in the Wizard window.
This displays the Design Variable page as shown in Figure 3-19.
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3-21 Chapter 3Working Model FEA: SolidWorks Exercises
Figure 3-19
Design Variable Page
2. Select Thickness from the Name list.
3. Accept the upper bound as 1.1 inches and set the lower bound
to 0.1 in. in the Design Variable Bounds region.
4. Click Next.
The Wizard prompts you to create another variable.
5. Click Yes.
This redisplays the Design Variable window.
6. Select RibThick
7. Set the upper bound to 1.0 inch and the lower bound to 0.1 in.
8. Click Next.
The Wizard prompts you to create another variable.
9. Click Finish and continue with the next section.
Specifying Constraints
A design constraint is a design response whose upper or lower limit valueplaces certain restrictions on the magnitude of the design variable(s)changes. For example, by decreasing the thicknesses, this part can be
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Exercise 3.2 Optimizing the Shape of a Bracket 3-22
made lighter but the maximum allowable stress will limit how far youcan reduce these dimensions. In this case, the maximum allowable stress
is your design constraint.
1. Click the Constraints tab in the Wizard window.
A dialog prompts you to accept a default constraint name.
2. Accept the default constraint name and click Next.
This displays the Design Constraints Response page as shown in
Figure 3-20.
Figure 3-20
DesignConstraint ResponsePage
3. Accept Response = stress and Component = von Mises and
Click Next.
The design constraint is applied to All Solids.
4. Click Next.
This displays the Design Constraint Limit page as shown in Figure
3-21.
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Figure 3-21
Design Constraint Limit
Page
The Type of Constraint defaults to stress, and upper bound
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Exercise 3.2 Optimizing the Shape of a Bracket 3-24
The Simulation Parameters tree-diagram displays the simulation
components. A default result set is created, displaying the load set
and restraint set that will be applied in the analysis.
2. Click Next.
The General Job Information page (Figure 3-22) displays the
parameters of the optimization job.
Figure 3-22
General Job InformationPage
3. Accept the default Optimization Result Set name, set the
maximum number of design cycles to 10 and accept the default
optimization type - Optimization plus sensitivity.
4. Click Next to continue.
This displays the execution option dialog.
5. Accept the default execution option Immediate automatic
execution and Click Finish.
This sends the optimization job to the solver. The message in the
MSC.Nastran window will inform you that the job has completed.
6. Click OK and continue with the next section.
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Processing Optimization Results
When the solver completes the job, the Results Wizard (Figure 3-23)displays. The Results Wizard contains all information about youroptimization results.
Figure 3-23
Results Wizard
The Results Wizard includes the following:
Optimization result setAccept the default current set.
Optimization exit statusProvides information about how theoptimization completed. For example, Optimization converged to anoptimal solution indicates that the optimization converged to a set ofdesign variables and all constraints are satisfied.
Information at final design cycleDisplays the optimized valueof the objective and the value(s) of the design variables.
1. Click Next and proceed to the next section.
Exercise 3 2 Optimizing the Shape of a Bracket 3-26
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Exercise 3.2 Optimizing the Shape of a Bracket 3-26
Interpreting Optimization Results
A number of graphs and bar charts are used to illustrate the outcome ofshape optimization. The Optimization Results window (Figure 3-24) liststhe three major categories of results that can be displayed in a graphicalform. The last option on this page updates the model geometry to thedimensions calculated for any one of the design cycles.
Figure 3-24
Optimization ResultsWindow
The following sections describe each of these results categories.
Design Cycle History Graphs
Design cycle history graphs show how a specific optimizationcomponent changes from its initial value to its final value through theoptimization process.
1. Select Design Cycle History Graph and click Next.
This displays the Design Cycle History Data window as shown in
Figure 3-25.
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Figure 3-25
Design Cycle History Data
A design cycle history graph can be created for any of the followingresult data:
Objective Function Shows how the design objective changedwith each design cycle.
Design Variable(s)Shows how one or more design variableschanged with each design cycle.
Design Constraint(s)Shows how one or more design constraints
changed with each design cycle. Maximum Constraint ViolationShows how the maximum
constraint violation changed with each design cycle (expressed as apercentage of constraint violation).
2. Select Design Variable(s).
The checklist box window shows the design variables Thickness and
RibThick. You can select either one of them, but for this display
accept both.
3. Click Next and continue with the next section.
Exercise 3.2 Optimizing the Shape of a Bracket 3-28
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p g p
Design Cycle History Scaling
You use the Design Cycle History Scaling window (Figure 3-26) tocreate and display a results graph.
Figure 3-26
Design Cycle HistoryScaling Window
.
1. Select No Scaling (true value) and click Next.
This displays a window that prompts you to create a graph. The
selections are as follows:
2. Select Create a Graph and click Next.
This creates and displays the graph.
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p g
Figure 3-27
Design Variable History
Graph
Note: In the following steps, a number of graphs will be displayed. Youcan close the graphs after viewing or keep them open to compare resultsbetween graphs.
3. Click Yes to display more optimization results and continue with
the next section.
This displays a window with more results graph selections.
Updating the ModelTo see how the geometric model changes is shape in each design cycle,open the Explorer or click on the Working Model FEA tab of yourDesktop Browser. Look for the Ex1_brkt_opt_Model and double clickon one of the model shape design cycle listings. Before updating themodel you can view stress results as described in this exercise. You canalso update the geometric model and the mesh to match any of the design
Exercise 3.2 Optimizing the Shape of a Bracket 3-30
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cycles. The purpose of updating the mesh is to be able to run a simulationanalysis of the updated model and get new stress, deformation, vibration,
or buckling results.
In the Optimization Wizard Results window:
1. Select Update the Model.
This displays the Model Update window as shown in Figure 3-28.
Figure 3-28
Model Update Window
2. Select the last design cycle from the list in the Select Design
Cycle region.
The Select Design Cycle list shows all design cycles that the
optimizer evaluated. Your selection is used to update the model.
3. Accept the default to update the mesh with the model.
The Information at selected design cycle provides the following
information:
ObjectiveThe value of the objective function at the end ofthe selected design cycle.
Design variablesThe value of the design variables at the endof the selected design cycle.
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Note: The values found for the last design cycle and the next-to-last
design cycle are generally identical, indicating that the results haveconverged.
4. Click Next.
The update will be based on the design variables found for the
selected design cycle. A dialog prompts you to update the model.
5. Click Yes to update.
This procedure will update the mesh and delete any results
associated with the original model.
6. Click on Finish to close the Results.
7. Click Close to exit the Wizard.
The bracket is updated as shown in Figure 3-29.
Figure 3-29
Updated Bracket
Exercise 3.2 Optimizing the Shape of a Bracket 3-32
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Viewing Stress Simulation Results
In this section you will display the stress simulation results of theoptimized model to verify stress constraints and see deflection values.
1. Choose Explorer from the Working Model FEA menu expand
Ex1_brkt_opt_Model_OptResults1.
2. Double Click on StressResultSet.
3. Close the Explorer.
View the stress simulation result contour as shown in Figure 3-30.
Figure 3-30
Stress Simulation ResultContour
You have completed this exercise.
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