From FreeCAD Documentation
- Select the shape you want to analyze. For volume FEM this needs to be a solid or compsolid. A compsolid is necessary if your part is made from multiple materials. (A compsolid can be created with the BooleanFragments command.) -- For shell and beam FEM somebody needs to fill in the details here.
- Press the FEM mesh from shape by GMSH button
- Optionally edit the minimal and maximal element size. (Autodetection works fine unless you apply complicated boundary conditions.)
- Click the Apply button and wait for the computation of the mesh to complete
- Close the task. You now should see a new FEMMeshGMSH object in your active analysis container.