I decided to “save as” in order to experiment but while retaining my original file/version. I saved the file as a different name and I reduced the protrusions by 1. When I ran the Netgen mesh routine I received the following warning which prevented going further:
FemMeshShapeNetgenObject::execute(): Access violation
I had just reduced from 14 to 10 protrusions within the same file and without issue so this time, reducing from 10 to 9, I thought perhaps access was locked due to a temporary file saved for auto recovery. I opened another copy of FreeCAD, same version, and I cleared one auto recovered file and I tried again but received the same message. I did search prior to clearing and the only instance listed on my C: drive when I searched for “fc_recovery_file” was a single file and from a prior day.
The model is parametric so I decided to simply update it. I went back to the file I used as the base for the "save as". During this process I've I learned a few things I thought I would share:
1) It meshed perfectly so I suspect the new file was still related to the old file and the older file was blocking access to the newer version hence “Access violation”.
2) The Analysis updates every time a parametric geometry change is made and most times after you make a change, especially changing the protrusions in an array, the constraints shift to nonsense faces because the numbering changes each time you change the geometry. In my case it delays each step by around 10-15minutes. To avoid this delete the analysis before making any changes; bite the bullet and re-create the analysis again. It made me wonder if there was a way to simply force the analysis to deactivate and not auto-recalculate. The combination of recalculate and auto-recovery with my model can take significant time as I mentioned; 10-15minutes after simple adjustments which normally take seconds.
3) The protrusions are the smallest mesh, most node intense, but removing one protrusion reduced the number of nodes by roughly 5000 and I was about 18400 over what I understand to be the limit of 350 000.
My computer is a relatively weak machine for this but I had a friend run the same analysis when I was getting the 3221225477 error and her machine with 32GB RAM i7 @ 2.60 GHz "ZBook" took almost exactly the same time as my machine took with 8GB RAM i5 @1.70 GHz 1.90GHz. Both were around 90 minutes.
I’m using the “Default” solver and I did see that in the preferences you can increase the number of processors but only if you use “spooles”… not sure what “spooles” is.
I also read in a thread from 2015 that auto recovery could be switched off. In my case I think the auto recovery function is roughly doubling the time it takes while the analysis is active. So I wish I could either disable the FEM auto-recalculate or if not possible the auto recovery. This is the thread which lead me to believe auto-recovery can be turned off:
https://forum.freecadweb.org/viewtopic.php?t=12345
Scott