Interpreting Complex Eigenvalues in Comsol Analysis

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SUMMARY

The discussion focuses on interpreting complex eigenvalues in Comsol during eigenvalue analysis. Complex eigenvalues arise when solving polynomial equations for their roots, particularly in applications like determining principal stresses in a 3x3 stress tensor. Users often question whether the absolute value of these complex eigenvalues can be used as eigenfrequencies. It is established that while complex eigenvalues indicate damping or instability in a system, they should not be directly interpreted as physical frequencies without further analysis.

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  • Understanding of eigenvalue problems in linear algebra
  • Familiarity with Comsol Multiphysics software
  • Knowledge of polynomial equations and their roots
  • Basic concepts of stress tensors in mechanics
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Engineers, physicists, and researchers involved in finite element analysis, particularly those using Comsol for eigenvalue problems and stability analysis.

ra123
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Hey,
Im working with Comsol and doing some eigenvalue analysis.
Why is sometimes the eigenvalues are complex numbers and not real number frequencies?
How should I interpret these complex eigenvalues?
Thanks
 
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They are sometimes imaginary because, at the heart of eigenvalue solving (the ones that I know of anyways) is solving a polynomial for it's roots. For example, finding the principal stresses in a 3x3 stress tensor is an eigenvalue problem. In that you are solving for the roots of a third order polynomial.
 
okaay great, so can i just take the absolute value as the eigenfrequency to work with?
 

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