I succeed in doing a simple mechanical simulation with two materials. I export in .vtk by passing the .frd file with freecad. Then I open with paraview. But the same approach does not work for a thermal simulation. Does Prepomax allow this?
What about using the built-in visualization module of PrePoMax? Does it not fit your purpose?
Good question! Probably prepomax is enough for analysis and visualization. On the other hand, paraview allows a very neat presentation. However, I forgot to admit that I know paraview better. I haven’t finished exploring the possibilities of prepomax, it’s my second day today!
FreeCAD doesn’t support thermal analyses, only thermo-mechanical ones. You can use other converters listed here: Converting results to ParaView format
I would recommend the second one (ccx2paraview).
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It would be good to know what is missing in PrePoMax for the visualization purposes.
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For me, the biggest advantage of ParaView for FEA results postprocessing is its Calculator filter that creates field output based on equations using existing results. Path plots (Plot Over Line filter) can also be very useful.
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Is it possible to create stress linearization in ParaView? I would need it for one of our projects, and I am considering adding it to PrePoMax if I find the time.
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THANKS! I will look at it!
Not really, it would require some tedious workarounds (likely involving the aforementioned filters). But FreeCAD can do it: FEM PostFilterLinearizedStresses - FreeCAD Documentation
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I saw that, but newer used it. If I find their code it will help me a lot 
I think it’s coded here: https://github.com/FreeCAD/FreeCAD/blob/391d08e6d54b37e1d6e03bb354b747ba72082ce0/src/Mod/Fem/Gui/Command.cpp#L1992
ccx2paraview…Super! ca fonctionne, Thank you!
I played with the Linearization tool in FreeCAD, and I don’t think it works as expected. Or maybe I do not know how to use it. I tried importing a rectangular beam loaded in bending and plotting the bending and membrane stresses using the tool. The result was not as expected. I got only membrane stresses and no bending stress.
Here’s what I got (notes: not exactly the same path and the units are different - Pa in FreeCAD, MPa in Abaqus):
It can be hard to compare it though. As you can see, Abaqus computes it in a more comprehensive way. In FreeCAD, it’s not well documented and we can only examine the source code to see what formulas are used.
I have a test based on a well-documented reference (*).
It could be used here to check the tool once is implemented.
Deviation with Mecway + ccx end up below 0.17%.
Deviation with Freecad + ccx is exposed in the webpage.
To compare with the analytical solution, one should look at
sxx_total / ( sxx_Membrane + Bending )
Expected value= 3.
Abaqus’ result is divided into components, and one must compute the equivalent stress out of it at the end.
However, the FreeCAD result shows no bending in the Membrane and Bending curve. The curve is the same as for Membrane only. It probably works on von Mises stress in the background where the sign of the stress is lost.
It takes the results of the previously created Line clip filter and, from what I understand when looking at the source code, it can use the following stress measures if they are plotted with that Line clip filter first:
- Mises
- Tresca
- max principal
- mid principal
- min principal
Only stress tensor components are not supported. But I got this when I switched to major principal:
Here are the formulas from Abaqus: https://classes.engineering.wustl.edu/2009/spring/mase5513/abaqus/docs/v6.6/books/stm/default.htm?startat=ch02s17ath56.html
The ones used by FreeCAD can be extracted from the source code if needed. They start around here: FreeCAD/src/Mod/Fem/Gui/Command.cpp at 1e212c32bc8ddf13443c1d61c1e403a9c5d6a5b6 · FreeCAD/FreeCAD · GitHub
P.S. I updated the FreeCAD wiki documentation for this tool to include the stress measures it can use.
It turned out to be easy to allow the usage of this stress linearization filter for stress tensor components so I sent a PR, it was merged and now the dev version of FreeCAD can perform stress linearization on all the available stress measures:
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