loss factor different in modal FRF vs Direct FRF

[modeldamper]

Hi
I have a frequency dependent material property for a visco elastic material and I run the Direct FRF solution. When I estimate the damping loss factor using X-modal software (by converting the FE output .pch file to .UFF file to import in X-modal), I get a value (say 0.1). But when I use the first value (just one shear modulus and one loss factor) in the frequency dependent material property and run the solution by Modal FRF solution (Modal can't run the frequency dependent VEM properties), the loss factor estimation is (0.15). Can anyone explain why I am seeing such a high value when I use the lowest value of the frequency dependent material properties?

Thanks

 

[GregLocock]

I don't know, but values like 0.1 and 0.35 are so high compared with normal structures that i'd guess that an attempt to fit curves would easily get confused.

Cheers

Greg Locock


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