Simcenter 3D Solutions Reuse the results of a Topology optimization

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How to convert STL file to precise geometry


1. Export the optimized model
1. In the Simulation Navigator, expand the solution node → Results.
2. In the Post Processing Navigator, right-click the Structural node and choose Material Density Results.
3. To work with a design cycle other than the last one, from the Result list, select the desired design cycle.
4. To change the minimum material density value for the solid elements, in the Solid Area subgroup, move the Lower      Bound slider to the left or right. 

Alternatively, you can type the appropriate value in the box and then press Tab. The range is from 0.0 to 1.0.
As you reduce the lower boundary, more solid elements appear in the optimization results. As you increase it, more solid elements are removed.
5. To change the color of all of the elements with a material density value equal to or greater than the defined lower boundary, click Color and then specify the color to use in the Color dialog box.
6. To better visualize the recommended design, select the Smooth (Nodal Average)  check box. 

The smoothing process averages the material density values between the nodes and displays that portion of each element that is greater than the specified lower boundary. As a result, smoothed results with the same number of elements might appear different with a different lower boundary. 

Note: If Smooth is selected, Verification Solution can´t be created.

7. To dynamically update the results in the graphics window as you change the display settings, select the Automatic Display Update  check box.

If you clear that check box, you must click Update Display in order to reflect your changes in the graphics window.

Select the Facets in STL Format  check box and click on Export to save the data to the Simulation folder.

    • Facets in STL Format—Exports the element free faces of the model as an STL file that you can import into the Modeling application.
    • Facets in Nastran BDF Format—Exports the element free faces of the model as a Nastran BDF file that you can import into the Pre/Post application.
    • Density CSV—Appears when the Smooth (Nodal Average)  check box is cleared. Creates a comma-separated values (CSV) file that indicates the material density value for each element in your model. This file also includes the lattice structure type and the lower boundary for the material density values for the solid and lattice areas.
All of these files are saved in the same folder as the Simulation file using the name [simulation_file_name]-[solution_name].[ext].
2. Import the optimized data

Change to the Modeling Environment.
    • Open the Part file of the model and load the optimized geometry afterwards.
    • Go to the Modeling Design, only then you can import the STL file!
    • Click à File à Import and select STL
    • Select the .stl file, created in the step before and open it.
    • You can see the original Part overlapping the optimized geometry.
3. Visualize the original and imported data

1. The original Part is overlapping the optimized geometry.

2. Go to the view tab and click on Edit Object Display.                                
3. Select the original geometry hiding the optimized.
4. Set translucency to 50%

5. Convert to precise geometry
1. Go to the Surface Ribbon and click on NX Realize Shape
2. Click on Cage from Facet Body
Select the “Facet Body Region” on which a new control cage should be create.

In the menu, you can choose the level of detail.
Be careful, a low Average Size will exorbitantly increase the computing time.
5. Keep in mind, that it also decreases the size of the created geometry patches, so they get tiny and make it harder to work with.
6. Finish NX-Realize Shape

6. Unite functional faces
1. As we used the original Part file, we can now use parts of this geometry to unite them with the optimized one in order to regain functional faces.
2. Use the unite command and select the bodies you want to add.
  • Right click on free space in the part navigator to deactivate the Timestamp order - then you have a list of all shapes present in the part
3. Unite the necessary parts from the original body with the optimized model.

7. Cut overlapping sections

It may happen that geometry overlaps your functional faces
    1. Select an edge of the functional face and extrude it.
    2. Set Boolean to Subtract in the Extrude Menu.

KB Article ID# KB000065759_EN_US



Associated Components

Samcef Desktop