Patran/Nastran Buckling Analysis – SYSTEM FATAL MESSAGE 7340 (LNNHERR)

[Nic0]

Hi everyone,

I'm currently working on a buckling analysis using Patran/Nastran on a thin Kapton structure (as part of a solar sail concept). The workflow involves applying prestress through a linear static subcase first, followed by a buckling step to capture possible wrinkling modes.

However, the solver crashes with the following fatal error:

SYSTEM FATAL MESSAGE 7340 (LNNHERR)
PROCESS ERROR REPORTED BY SUBROUTINE LNNP2CS (IER= -725)
USER INFORMATION: NUMBER OF COMPUTED EIGENVALUES EXCEED ALLOCATED STORAGE.

Even when I reduce the number of requested eigenvalues (e.g., to just 3), the error still appears.
I'm using a mesh of approximately 3,800 shell elements.

Has anyone encountered this before? Is there a way to increase the allocated storage or tune solver parameters to avoid this issue?

Any help would be greatly appreciated.
Thanks in advance!

Best regards

 

[ThomasH]

I think have encountered something similar. The problem might be that the static subcase buckles the structure. I that case you may be able to use part of the buckling load to "balance" the system.