So I spent the day with trying to solve my problem. I attached the model too look on (without mesh as suggested) if anyone is interested.
The model has a simplified geometry, as the half-pipe shaped stiffeners should be a helix. I could create that but the geometry was warped for some reason and meshing was unsuccesful. The attached model is a good aproximation of the real geometry (at least for my aims).
There are a bunch of observations from my experience with the model:
FreeCAD is promising, and the FEM WB is certainly something to consider to use for calculation. Please don't take the following as an insult, I may have pushed a little the boundaries here
Creating the mesh with the settings auto shape, max: 100 mm, min: 20 mm takes about 2 minutes on my laptop, setting max to 50 mm yields meshing time well over 20 minutes. When running the static analysis FreeCAD reports a succesful analysis, athough it fails for some reason, as seen in the output window:
"FEM: No nodes found in Frd file.
Problem on frd file import. No nodes found in frd file.
FEM: No result object in active Analysis."
Perhaps due to model size? I could not figure out based on the ccx printout (attached). A less dense mesh (say max 150, min 20) runs, but provides inaccurate results, as the mesh itself is incorrect (negative jacobians etc.).
I used ccx directly (v 2.10) to run the bucking analysis - the experience is roughly the same.
So making meshing better by providing more control (element type? quad mesh? zones? the ability to mesh only certain regions of the model?) and a faster algorithm would certainly improve the overally experience and usability. I'll check meshing the model using macway later tonight, that has some more options if I remember correctly.
I came across the following issues. During the day I several times re-started the work from scratch, and I'm obviously not an experienced user. This is not not an exhaustive list and I may be wrong on some issues.
- meshing, as elaborated above.
- the defined material sometimes gets lost, probably during save/load.
- the ability to select multiple faces for loading, material, thickness etc. would be great.
- I met the infamous "Pressure on shell mesh at the moment only supported for meshes with appropriate group data." error, althogh the checkbox in Preferences/FEM is checked. Checking out-in this checkbox seems to work. As I get the German version of the GUI, reading the English forum is not always helpful.
- Localisation issues. Is it possible to enforce one?
- Having some feedback from the meshing process (e.g. progress) would be great, watching the memory consumption of gmsh in the task manager if it hangs is not really informative.
- It would be nice to have the output window scroll automatically to always show the last line, or at least enable Ctrl-End to jump to the bottom.
- Is it possible to define constraint on a vertex? One can do it in FreeCAD but is it transferred to ccx? I could not make it work.