I am giving sinusoidal point load excitation on the top face of a rectangular block. The block is fixed at the bottom. I have a peak at 26Hz in the frequency response from harmonic analysis. But in modal analysis the frequency varies from 59 to 200Hz. Why is it so?
Sir - Are you saying that you are getting two sets of natural frequencies when you use the modal analysis and Harmonic analysis or is the difference only in the first frequency? Your structure seems simple - perhaps you can calculate them analytically and verify?
Modal analysis is a free free run condition in which there will not be any load action ffg on the member. So, it will give you the cumulative range of natural frequency were as harmonic analysis is load specific
hi
I don't recognised your question perfectly.
In your case, perhaps you have different mesh setting in two analysis, maybe you don't apply loads similarly and ...
So I recommend you to set a good mesh (better to do convergence test) and do the same setting in modal analysis.
Note that modal analysis in your case, include pre-stress, it means you must do a static structural analysis before modal analysis.
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