topic Re: Iterative Modal Analysis in Robot Structural Analysis Forum

Iterative Modal Analysis

Anonymous — Wed, 11 Jul 2012 18:25:37 GMT

Hello!

I'm trying to do a iterative Modal (Pseudo Mode) analysis of a roof steel structure, but I'm getting error nº101 (incorrect data: Improper element number).

I don't understand what's gone wrong or why the element number is relevant for the analysis. I also try between different mass matrix type but it always stuck in same error nº 101...

Can you help please.

Thanks

Re: Iterative Modal Analysis

se2p — Thu, 12 Jul 2012 00:13:39 GMT

Do a renumbering begining at 1000 just in case.
Lumped without rotations should be a good choice for a bar made structure. Disable sturm check. See if it helps

Re: Iterative Modal Analysis

Artur.Kosakowski — Thu, 12 Jul 2012 06:07:31 GMT

Please attach the rtd file.

Re: Iterative Modal Analysis

Anonymous — Thu, 12 Jul 2012 08:33:21 GMT

I try the renumering of bars, it doesn't work.

Also try the diferent add mass types, global and dynamic, with same result, error nº101...

In attach you can find the model,

Thanks Arthur

Re: Iterative Modal Analysis

Artur.Kosakowski — Thu, 12 Jul 2012 09:56:58 GMT

Please set the solver as Auto.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

Re: Iterative Modal Analysis

Anonymous — Thu, 12 Jul 2012 10:23:28 GMT

A usual direct modal analysis with eigenvalues work fine, for this particular case.

I'm starting to settle the modal analysis type on this substruture to lead to a global spectral analysis much more consuming. For what I understand, for bigger and complex models, obtein natural frequencies with iterative PCG_RITZ method will be the best choice, but I'm stuck in this error...Ii cannot know why.

Thanks

Re: Iterative Modal Analysis

Artur.Kosakowski — Tue, 17 Jul 2012 12:53:07 GMT

The iterative multilevel solver is not compatible with rigid links (error 101). For large models (above 500000 d.o.fs) I would recommend use of the multi-threaded solver with block subspace iteration for 50-100 modes or Lanczos for more modes.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.