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Damped Eigenfrequency Analysis
Posted May 28, 2020, 4:38 a.m. EDT Structural & Acoustics, General, Structural Mechanics Version 5.2a 1 Reply
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I am working mode test from eigenfrequecny analysis using Solid mechanics. My problem is when I add damping in the form of isotropic loss factor to thr linear elastic material, it would increase the real part too (which is frequency of the system) that should decrease with the increase in damping. Both the real and imaginary part are increasing simultaneously.
Here is what I understand the manual: When the damping subnode is added to the Linear Elastic Material node, the damping type is always Rayleigh damping.
I want to know if what I understand is correct and if this is the cause of the problem mentioned above.
Help would be appreciated.
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Hi,
How damping is handled, including the apparent stiffening effect of loss factor damping, is explained in detail in these blog posts
https://www.comsol.com/blogs/damping-in-structural-dynamics-theory-and-sources
https://www.comsol.com/blogs/how-to-model-different-types-of-damping-in-comsol-multiphysics
https://www.comsol.com/blogs/frequency-response-of-mechanical-systems/
You will not get Rayleigh damping unless you explicitly use that option. It is the default option when you add a Damping node. Loss factor damping is probably the most used option, but it is only valid in frequency domain.
-------------------Henrik Sönnerlind
COMSOL