Modal analysis with interactions turned on

[AleksaBgd94]

Hello everyone,

is it possible to run modal analysis with interactions turned on in the model? I would like to determine the frequency of the system that actually has interactions between its parts? I tried with procedure type Linear perturbation (Frequency).

Thank you in advance

 

[FEA way]

Which software do you use - Abaqus ? If yes, you should use tie constraints. Contact can’t change its state in linear perturbation analysis and would have to be linearized to work in such a study.

 

[AleksaBgd94]

Hello,

thanks for the quick reply. Yes, I use Abaqus. Sorry, I see I didn't write in DASSAULT: ABAQUS FEA SOLVER section as I thought...

I agree I could go with tie contacts, that should work, right? I am actually working on determination of frequencies of masonry walls (composed of bricks and mortar). Since I model mortar by specifying different parameters in interaction etc. I usually have interactions turned on in the model. But in this case I would need to replace them by tie constraints. Since it is the linear range, I think it is actually nothing expected to happen in mortar connections... I will try it this way...

Thank you and kind regards
ALeksa

 

[AleksaBgd94]

I forgot to ask ... Is there any possibility then to include interactions in the model while carrying out modal analysis in Abaqus? Thanks.

 

[FEA way]

There is a Linear Complementarity Problem (LCP) solution technique in Abaqus that allows you to include contact in linear perturbation analyses but it only works for static perturbation steps, not eigenfrequency extraction ones.

 

[AleksaBgd94]

Ok. Thank you very much.

 

[GregLocock]

In general non linear type problems, including contact, result in an amplitude dependent frequency of strongest response, and some sort of time based simulation is needed to establish the peak frequency.

Cheers

Greg Locock


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