ABAQUS Keywords Reference Manual  

*COMPLEX FREQUENCY
Extract complex eigenvalues and modal vectors.

This option is used to perform eigenvalue extraction to calculate the complex eigenvalues and corresponding complex mode shapes of a system.

Product: ABAQUS/Standard  

Type: History data

Level: Step  

Reference:

Optional parameter:

FRICTION DAMPING

Set FRICTION DAMPING=NO (default) to ignore friction-induced damping effects.

Set FRICTION DAMPING=YES to include friction-induced damping effects.

Data line for complex eigenvalue extraction: 

First (and only) line:

  1. Number of complex eigenmodes to be extracted. If this entry is omitted, all the eigenmodes available in the projected subspace, formulated on the basis of all eigenmodes computed in the preceding *FREQUENCY step and possibly reduced by using the *SELECT EIGENMODES option, will be extracted.

  2. Minimum frequency of interest, in cycles per time. If this field is left blank, no minimum is set.

  3. Maximum frequency of interest, in cycles per time. If this field is left blank, no maximum is set.

  4. Shift point (positive or negative), in cycles per time. The eigenvalues with the imaginary part closest to this point will be extracted. The default value is zero.