To all
I am seeking some explanations or inputs in understanding groundcheck & autospsc
I have a large model and groundcheck flags some FAIL for the N+AUTOSPC-SET (G & N are OK). I spent some time “breaking” down the model and have found one possible components creating the issue. The component is all made of 2nd order shell elements (and that is it). So here is the problem;
If I run this component (alone) in a free-free state (sol103) it fails the following check
RESULTS OF RIGID BODY CHECKS OF MATRIX KNN+AUTO (N+AUTOSPC-SET) FOLLOW:
PRINT RESULTS IN ALL SIX DIRECTIONS AGAINST THE LIMIT OF 2.567568E-03
DIRECTION STRAIN ENERGY PASS/FAIL
--------- ------------- ---------
1 1.707525E-08 PASS
2 3.901226E-08 PASS
3 2.792519E-08 PASS
4 2.264839E+07 FAIL
5 1.145173E-03 PASS
6 3.059997E+06 FAIL
I then converted this back to 1st order shell and it passes the check
RESULTS OF RIGID BODY CHECKS OF MATRIX KNN (N-SET) FOLLOW:
PRINT RESULTS IN ALL SIX DIRECTIONS AGAINST THE LIMIT OF 1.224691E-03
DIRECTION STRAIN ENERGY PASS/FAIL
--------- ------------- ---------
1 1.441322E-09 PASS
2 1.443595E-09 PASS
3 1.371518E-09 PASS
4 1.416246E-05 PASS
5 3.985814E-05 PASS
6 5.953556E-05 PASS
I notice that the 1st order model does not have the AUTPSC flagged
Why does the 2nd order shell element FEM “fails” the groundcheck?
All other (standard) checks appears to be ok.
FYI: the difference between both models for the 1st flexural frequency is <1%
Any help/advice/explanation would be welcome
