Tutorial 10: To Simulate Support Structure Modeling and Failure

Create support structures in Netfabb and test their performance in Simulation Utility.

Video length (8:39).

Support structures are used to mitigate excessive distortion during powder bed processing. However, these structures are themselves subject to the same forces that distort the part. In this tutorial, a geometry with a large overhang area is modeled using homogenous support structures, with options enabled to check for support structure failure.

We will use Netfabb to create support structures for this part. Follow the step-by-step instructions shown in the video. Sample files for use with the tutorials are available on the Download Page.

Note: If you are running Simulation Utility LT, the Mesh Settings in this exercise require that you solve the simulation on the Cloud.

1. In Netfabb, click Prepare menu > Load Machine Workspace > Generic Open Machine.
   
2. Click File menu > Add part and add the sample file Example_10.stl .
3. In the left pane, make sure that Force parts above platform is not checked.
4. To check part position in relation to the platform, at the top of the window click Move Parts and in the dialog, review the current Z value.

   It is important for this exercise to place the part on the platform, with a Z value of 0.00 mm, rather than floating above it. You can use the Translation Z control in the dialog to move the part to the correct position.

5. Click Create Supports.
   
6. At the bottom of the window, click Run Support Script, in the Choose support script dialog select SLM, and click Execute.
   

   The lattice-like supports are created.

   
7. Click Apply Support.
8. Click Simulate Process; in the dialog that opens, enter a suitable file path and name, such as Example 10, leaving in place the file extension .3mf. Click Save.
9. In the Simulate process dialog, select Unify support volumes for simulation, which runs a simple repair process to improve the mesh quality. Also select the Simulation Utility version, if both are available, and click Start Simulation.

   The exported file takes a minute or so to generate, then opens inside the Simulation Utility window.

10. In the Simulation Utility Browser, right-click on the support structure, which has a name that includes _hulledsupport_, and select Edit Geometry.
    

    One benefit of using Netfabb to generate supports appears here, in that the Volume Fraction is automatically calculated during support creation. Volume fraction is the amount of the support volume that is occupied by physical structures rather than empty space. Leave the existing value unchanged.

11. On the Home tab, click Machine to start setting up the simulation.
    
12. In the Machine dialog, set Machine Model to Generic Open Machine and Processing Parameters to Inconel 625.
13. Click OK to close the Machine dialog, and click Build Plate > Size tab, then click Snap to X and Y.
14. In the Build Plate dialog, click the Properties tab; here deselect Match part deposition material and set Material to SAE 304.
    
15. Click OK, then click Mesh Settings. Set the Meshing approach to Wall thickness, and Minimal Wall Thickness to 2 mm.
    
16. Click OK, then click Solver Settings. On the Analysis tab, select Include Support Structure Failure, and set the failure criteria to 1000 MPa.
    
17. Click Solve to start the simulation, and save the project with a descriptive name.
    
18. When the simulation completes, a prompt will ask to import the results. Click Yes.
19. Click Results tab > View Logs to read the solver output.
20. In the Log Files window, click the Mechanical tab, and scroll down, looking for Warnings.
    

    You may see several warnings of support structure failure. These indicate that the support structure failure criteria, specified in MPa units in the Solver Settings, was exceeded during simulation.

21. In the Browser Results folder, use the light bulb icons to show the Structure Type results. In the Animation panel, move the increment slider to the far right to view the last increment before build plate removal.
    

    The Structure type results are color coded into 6 different element types, and the failed support structures are clearly visible in red.

22. If you want to turn off the element edges display for a clearer view, right-click in the Results Browser, select Render Properties, and deselect Element Edges.
    
    
23. Use the light bulb icons to show the Displacement results.
24. Click Plot Settings .
25. Select Warp by Displacement, and change the Displacement Scale to 5.0 to exaggerate the displacement five times. Click OK to exit the settings dialog.
    

    For this example you may want to turn the element edges back on in the Render Properties dialog. The warped displacement results with visible element edges should look similar to the figure below:

    

    Note that the elements at the support-part interface look distended. Rotate the part and zoom into the distended region.

    Observe the excessive displacement of the part at this location. You may want to go back to the Mechanical log file and make note of one or more specific time increments when the warnings of support structure failure occurred. Then you can enter those times into the Time field on the Animation panel of the Results tab to see the state of the build at each time.