Stresses in Force Freq Analysis

[VN1981]

Hi,
I wanted to understand the math behind how FE softwares calculate stresses in Forced Frequency Analysis.

In a free-free run, all we get is normal mode shape and corresponding Eigen value (resonance frequency). But in a forced frequency run, apparently the displacement values are real (physical) and from what I understand, from displacement output, values of strain & stress quantities are calculated.

Anybody know how? Even if they can point out sources which give out the math, it would be helpful. Just want to get a generalized idea about the internal workings.

 

[mfritze]

Check the theory manual for whatever package you are using. Most (solidworks simulation being the exception) have very good documentation on underlying math.