The Mesh WB doesn't view the import/export process as an attempt to "edit" a given mesh file -- on import it is throwing away a tremendous amount of data when reading a NASTRAN file, and then it's converting any QUAD4 elements into triangles. Further, when you edit a mesh in FreeCAD's Mesh WB, no particular attempt is made to preserve the original node numbering, because to MeshWB that's not an important part of the mesh. So an exported NASTRAN mesh from MeshWB is unlikely to bear much resemblance to the original imported mesh, even if no changes are made to it. And if you've edited the mesh, it's going to be completely different.aerospaceweeb wrote: ↑Sat Oct 02, 2021 9:13 pm Another MASSIVE problem is that FreeCAD can't import something, and then export it without changing it in an unpredictable way.
Namely, FreeCAD changes the IDs of every single object in the mesh when it imports it, and then changes the IDs again, in a way I don't fully understand, while exporting it.
These problems are not insurmountable, but they aren't trivial, either. FreeCAD is designed to be sort of "file-format-agnostic" -- it's not clear that the Mesh WB is the place to code in special handling for something like a NASTRAN file -- to me that feels more like something that should happen in Fem.