Shape Finder

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Shape Finder

• Workshop A13

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Workshop A13 - Goals

• To use the DS shape optimization tool to indicate
  potential geometry changes that will result in a
  reduction in part mass.
• To request a 40 reduction in the part mass.
• To create multiple tree branches in the DS GUI in
  order to allow results comparisons after solving.

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Workshop A13 - Assumptions

• The geometry for workshop 8 consists of 2
  Parasolid files. In actual practice users would
  typically bring geometry from their preferred CAD
  system and simply update as needed. For training
  purposes we provide the original as well as the
  modified geometry files.
• The geometry and boundary conditions in this
  workshop is extremely simple. The workshop is
  intended to demonstrate the basics of shape
  optimization without undue time spent during
  preprocessing and solution.

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Workshop A13 - Start Page

• From the launcher start Simulation.
• Choose Geometry gt From File . . . and browse
  to the file Bracket_Opt.x_t.
• When DS starts, close the Template menu by
  clicking the X in the corner of the window.

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Workshop A13 - Start Page

• Choose the Metric (mm) unit system.
• Units gt Metric (mm, kg, MPa, C, s).
• Highlight the Mesh branch.
• In the detail window set the Relevance 100.

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Workshop A13 - Preprocessing

• Change selection filter to body select and
  select the part.
• RMB gt Insert gt Element Shape
• Change the detail to All Tetrahedrons.

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Workshop A13 Meshing Notes

1. Because of the nature of topological optimization
   it is recommended that the mesh relevance be high
   during a shape run.
2. Shape optimization allows ONLY tetrahedral
   element shapes. While some geometry will
   automatically be tet meshed, other cases will
   require the mesh control for element shape be
   used. In this workshop, for example, the
   geometry could be sweep meshed resulting in a hex
   element mesh.

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Workshop A13 - Environment

• Make sure the selection filter is reset to
  surface select.
• Highlight the Environment branch.
• Select the surfaces of the 2 cylinders shown
  below.
• RMB gt Insert gt Fixed Support

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. . . Workshop A13 - Environment

1. Select the surface of the cylinder shown below.
2. RMB gt Insert gt Force.
3. Change to Component method.
4. Enter X 10 N Y 5 N.

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Workshop A13 - Solution

• Highlight the solution branch.
• RMB gt Insert gt Shape Finder.
• Enter 40 in the Target Reduction field.
• Solve

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Workshop A13 - Result

• When the solution is complete highlight the shape
  finder branch to view the results.
• The red region in the plot indicates where we can
  potentially remove material while maintaining the
  parts structural integrity. The detail shows
  that we have achieved a 40 reduction in mass.

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. . . Workshop A13 - Result

• While the result is a conceptual guide to where
  material might safely be removed we can use the
  ruler tool in the graphics window to better
  quantify how to modify the part.
• Based on these results we would typically return
  to the geometry source (CAD) to make
  modifications.

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Workshop A13 - Verification

• Remember! The results of a shape optimization
  solution indicate only where the optimal regions
  are that material can be removed. Nothing is
  implied about how the part will perform after the
  material is removed.
• Sound engineering practice requires that we test
  any new design to insure its performance is not
  compromised.
• If we were using a commercial CAD system (or
  DesignModeler) we could simply modify the
  original geometry and Update the Simulation
  model to continue.
• In this workshop we began with a Parasolid file
  and will now import another Parasolid model
  representing the modified original part.

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Workshop A13 - Start Page

• Highlight the Model branch and RMB gt Duplicate.
• With Model 2 highlighted choose Geometry gt From
  File . . . .
• Browse to the file Bracket_Opt_2.x_t and Open.

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. . . Workshop A13 - Verification

• Since this new geometry represents our optimized
  part we wont use the shape finder again,
  rather we will now solve the model for the
  appropriate structural results.
• By duplicating the original model all definitions
  are in place, however the scope of the boundary
  conditions must be established on the new model.

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Workshop A13 Scoping

1. Highlight the Fixed Support in environment 2
   (notice the Geometry field is undefined).
2. Select the cylindrical surfaces where the
   constraints are applied and Apply in the detail
   window.

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. . . Workshop A13 Copy/Paste/Scoping

• Repeat steps 18 and 19 for the force in
  Environment 2.

Highlight the Shape Finder object in
Environment 2 and RMB gt Delete
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. . . Workshop A13 - Verification

• With the solution branch highlighted for Model 2.
• RMB gt Insert gt Stress gt Equivalent (von Mises).
• RMB gt Insert gt Deformation gt Total.
• Solve

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. . . Workshop A13 - Verification

• The final step in Shape Optimization is to
  evaluate structural results to determine if the
  changes in the geometry have degraded the desired
  performance of the structure.

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