Tech Tip – Reverse Engineering Your Deformed Results in ANSYS

kaan-80x80The deformed geometry capability in ANSYS R17 is one of the most powerful and easy to use new features in the latest release of ANSYS. In addition to the new workflows that it enables, you can also easily reverse engineer your deformed results using ANSYS SpaceClaim. In this post I’ll show how to take your deformed geometry to another ANSYS analysis. Then I’ll show how you can use the powerful reverse engineering features in SpaceClaim to make your deformed results into a geometry again.

Deformed Geometry – Analysis to Analysis

Where previously you needed to create named selections and use scripts with intermediate MAPDL and FEModeler systems, now you can just drag and drop connections on the Workbench schematic:


A couple of notes:

  • For dynamic analysis that use the Linear Perturbation method, this happens behind the scenes on the mesh already. No need to apply this for the standard harmonic analysis.
  • If you want to use this parametrically, you will need to apply loads on the downstream analysis with APDL or loads that are compatible with nodal named selections. All other named selections and loads will be lost/unassigned when the deformed geometry is updated.
  • The shape but not any stress states are transferred. If stress states are desired, the INISTATE APDL command will be necessary.

Deformed Geometry – Analysis to Geometry

You are not limited to just sending deformed geometry to another analysis, you can also send it back to a geometry using tools that you probably already have. Here we will work with a metal forming test case, done with ANSYS Autodyn. See this workflow in the video below.


The first step is to right click on the desired geometry result and select Export -> STL


The STL format is a faceted data format, which is not strictly compatible with the types of geometry that ANSYS and most CAD systems expect. You can think of it as a surface mesh of triangles around the geometry. It is not explicitly associated with a volume and if the quality of the STL file is poor, filling the mesh can be problematic. An STL surface mesh simply converted into a volume is a relatively inefficient way to represent geometry for ANSYS. Luckily we can do some reverse engineering in ANSYS SpaceClaim, a tool which you may already have.

Notice that our shell elements from ANSYS are represented as 3D in the exported deformed geometry. The STL file is brought in as a mesh body type. ANSYS SpaceClaim is used extensively in reverse engineering. We can see that we have a few options in the Insert -> Reverse Engineering section of the ribbon interface.


We will be using the Skin Surface tool. This allows us to define surface bounds and control points to create a surface corresponding to a surface mesh region. The initial attempt is fairly imprecise:


What happened here is that the surface mesh fitted to both the top AND bottom sides of the thin body. The primary way to deal with this is to sample smaller, less complex areas of the surface. The Skin surface tool lends itself naturally to this workflow of creating patches of several different surfaces.


See this video for more information on the reverse engineering features can capabilities of SpaceClaim.

Optionally we can also improve the quality of the mesh to better resolve the curvature using the Facets tab, enabled by an add-on license to SpaceClaim. It is used commonly in 3D printing applications and it has tools for working with dirtier meshes than what we will generally export from ANSYS.


Once we have all of the surfaces fitted and created, ideally it will turn into a solid automatically. There will typically be precision issues, though, that keep the surfaces from forming an airtight volume. The Repair -> Solidify section has tools to help with this. After fixing some small gaps we have a solid geometry.


Afterwards it is good practice to check the Deviation of how well the geometry matches the source mesh. We can do this in the Measure -> Deviation tool. Notice how the carefully created top surface patches have better deviation than the quick and dirty bottom surface patches.


Hopefully you’ve found that helpful!

If this was useful to you and you’d like to hear other ways to speed up your simulations contact us or subscribe to our newsletter below:


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