Steel wheel in PrePoMax

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steel wheel rotating with FEM stress
Steel wheel with "von Mises stress" results

Keep the wheels turning. A steel wheel with shell elements has been on my list for a long time. In the past, I always had only aluminum rims with solid elements in the simulation (see In this post I want to focus on the FEM calculation in PrePoMax.

half steel wheel geometry FEM mesh displacements and stress in PrePoMax
Progress in PrePoMax (geometry, FE mesh, displacements & stress)

I made my own steel design and that is inspired by the wheel of the Sono Sion ( media-gallery). I used an existing printable 3D model from and derived from that a surface geometry in FreeCAD. And I also punched “” into the disc with FreeCAD.

steel wheel geometry in FreeCAD
Steel wheel geometry in FreeCAD

I prepared a shell mesh and defined a steel material for disc and rim. The disc mesh group is connected with tie contact to the rim.

steel wheel with FEM mesh in PrePoMax
FEM mesh groups connected with tie contact

I defined a vertical load at the shoulder of the rim over a section of 36 degrees. And fixed the wheel at the five bolt holes in the middle.

steel wheel load step definition in PrePoMax
Load step with “Loads” and “BCs”

Now we can submit the calculation with “Run” in Analysis. On my computer it takes lesser than 3 minutes to calculate all six load steps in the CalculiX solver.

Now we can check the results. First of all, always check the deformations.

steel wheel displacements FEM
Deformation of the wheel

Next we can take a look on the stress. Make sure that you are looking at the expanded form of the shell elements (see keyword OUTPUT=3D). Otherwise you will not find the bending stress (compare stress inside and outside in next figure).

Steel wheel with FEM stress in inside and outside
Signed maximum absolute principle stress inside (left with transparent rim) & outside (right)

You can use the “Exploded View” and “Section View” option for a closer look into the contact area between disc and rim.

steel wheel half with FEM stress animated
Stress check with the “Exploded View” and “Section View” option

If you need more possibilities to plot the results or if you like to use ParaView then the CalculiX result file (*.frd) can be converted into the ParaView VTK format (*.vtu). In the PrePoMax Forum you can find the useful tip “Converting results to ParaView format“.

steel wheel von Mises stress animated GIF
“von Mises stress” in ParaView and animated as GIF

If I am honest, I did not expect such good results and so many possibilities when I use only free available opensource software.
I could also imagine a fatigue calculation in Fatlab or even an additional load case cornering.

Give PrePoMax a try and if you like you can load this example from the steel wheel pmx file (9 MB).