Substructuring vs. CMS

[meshparts]

Hello,

I have done some comparison simulations using the Substructure and CMS (Component Mode Synthesis) techniques in ANSYS.

For statical analysis both methods are very accurate, compared with the results of the full model.

For modal analysis I'm getting totally wrong results when using the substructure technique. On the other hand CMS works just fine.

So the question is: Why dose the substructure technique works just for static simulations? Am I doing something wrong? I think so, but where? Both stiffness and mass matrices are written so why dose the statical analysis work but the modal not??

Thanks in advance!

Regards,
Alex