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Real Eigenvalues Analysis / Eigenfrequency analysis

Dear Experts,

 

I have a short question and hope, the answer is also short:

 

How do I analyse the Real eingenmodes of a pre-stressed system?

 

I would like to get th natural frequencies of a system with bolt preloads.

What is the correct way to set up the simulation?

 

All answers are wellcome.

 

Best regards, Michael

 

3 REPLIES
Solution
Solution
Accepted by topic author MiDi1791
‎11-16-2015 06:06 AM

Re: Real Eigenvalues Analysis / Eigenfrequency analysis

You need a subcase containing the static preloads prior to the modal subcase.

 

In the modal subcase, include a "STATSUB=n", where n is the ID of the previous static subcase. This augments the stiffness for the modal subcase with the differential stiffness due to the static subcase.

 

See the QRG for more information on STATSUB.

Re: Real Eigenvalues Analysis / Eigenfrequency analysis

Hi JimB,

 

thank You for answering. I will try it in the way You described.

Last question: What do You mean with "QRG"?

 

Best wishes,

Michael

Re: Real Eigenvalues Analysis / Eigenfrequency analysis

QRG = Quick Reference Guide in the online help