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Free body modal analysis

Hello Femap experts,

 

Could you help me with an issue about modal analysis? 

 

I'd like to know if it is possible to execute a modal analysis and if it is necessary to use freebody data/tools.

 

Attached you will find a body that we wish to analyze in order to find its natural frequencies, this body will be only hanging from the top surface.

 

Because modal analysis is asking for a movement constraint, the question is: can we do the analysis without a movement constraint, even if it is a nonlinear (maybe) analysis?

 

Any help will be very useful... thank you.

1 REPLY

Re: Free body modal analysis

Natural frequency analysis can be done with or without constraints.  If analysing without constraints, then the first 6 modes are 0 Hz rigid body modes (ie. "floating" modes where there is no strain / elastic energy in the structure itself).  The 7th mode is the first structural mode, asssuming there are no other "mechanism behaviours" within the modelled structure.