Tutorial: Generating CAD and Analyzing Results

Learn how to fit a PolyNURBS to a smoothed result.

In this lesson you will learn how to:
  • View and smooth an optimized shape
  • Generate CAD by fitting a PolyNURBS to the smoothed result
  • Modify the CAD to better contact the non-design spaces
  • Analyze the modified shape and view the results


Open the Design Concept Model

  1. Press F7 to open the Demo Browser.
  2. Double-click the Analyze Design Concept.stmod file to load it in the modeling window.


  3. Press F2 to open the Model Browser. Verify that the Max Stiffness Mass 30% result alternative is selected.


  4. Make sure the display units in the Unit System Selector are set to MMKS (mm kg N s).

View and Refine the Optimization Results

  1. Click the Structure tab on the ribbon.
  2. An optimization was previously run and saved with the model. Click Show Optimization Results on the Optimize icon to view the Shape Explorer, or simply double-click the optimized part.


  3. Position the topology slider on the Shape Explorer two ticks from the far right. This is the point at which the generated shape is fully connected, which is important when fitting PolyNURBS to the result. Your analysis results and CAD conversion will vary depending on where you position the slider.


Smooth Results and Fit PolyNURBS

  1. Select the Smooth Results option on the Shape Explorer. (This setting may already be selected if you used it previously during the session.)
  2. Click the icon on the Shape Explorer.
  3. Experiment with the options on the dialog and see how this changes the smoothness of the optimized result.
    • Drag the slider to the right to increase the smoothness.
    • Maintain part volume while smoothing is the default option. Ignoring the part volume tends to provide even smoother results, but material may appear thin or be removed entirely in some regions.
    • Increasing the number of smoothing iterations will also produce a smoother result.
  4. This dialog is also where you can adjust settings for fitting a PolyNURBS to the optimized result. Try using the default settings first.
    • Crease break angle is a threshold value. When Auto creasing is enabled, any break angle above the value entered will have high sharpening applied to the edge.
    • Lowering the Element density factor will increase the size of the PolyNURBS cages, but will capture less detail. The default value is 1. In general, you want to use the lowest density factor possible that still captures the geometry.
  5. Click in the modeling window to close the dialog.
  6. Click the Fit PolyNURBS button on the Shape Explorer. This automatically generates a PolyNURBS and opens the PolyNURBS tool.
  7. Double right-click to exit the PolyNURBS tool. This converts the PolyNURBS to a CAD part, which appears as PolyNURBS Fit in the Model Browser.

Eliminate Gaps Near Non-Design Spaces

  1. Press F5 to view the Model Configuration toolbar, which appears at the top of the Model Browser.
  2. Deselect the rocker check box to configure off the initial part. This will exclude it from any calculations.
  3. Double-right-click in the modeling window to close the Model Configuration toolbar.
  4. Use the scroll wheel to zoom in on the areas where the PolyNURBS contacts the three boss parts. Notice that the PolyNURBS part has gaps near these non-design spaces.
  5. Use the Contacts tool on the Structure ribbon to locate and review these gaps.
  6. Fix these gaps using the various PolyNURBS tools on the Geometry ribbon so that high stress concentration areas are not found in the subsequent analysis.

Analyze the Modified Shape

  1. Click on the Analyze icon on the Structure ribbon to analyze the modified shape.


  2. Set the Speed/Accuracy setting to Faster.


  3. Click Run.
    Depending on how well the cleanup went in the previous step, you may get a warning message similar to the one below:


  4. Click Continue.
    A green check mark will appear when the analysis is complete. (This may take several minutes.)
  5. Double-click on the name of the run to view the results, which are displayed in the Analysis Explorer.

View the Analysis Results

  1. In the Analysis Explorer under Load Case, select the Jump load case and the Displacement result type.


  2. The maximum displacement shown in the legend should be approximately .5 mm, but your results will vary depending on where you positioned the topology slider and how you modified the geometry near the non-design spaces.


  3. Click the button under Animation to view the displacement. Click the button again to stop the animation.
  4. With the Jump load case still selected, switch to von Mises Stress for the result type.


  5. Click the icon and select Hide all loads and supports.
  6. Orbit the model to check that there are no hidden red areas.