Evaluating damped natural frequencies using Readmac function in Hyperstudy

Hi Simon,

Readmac function in HyperWorks returns a vector of 3 outputs: eigenvalue, MAC value and ID of the best matched mode. In Normal Modes, the eigenvalue is a single value which is real output. However, In Complex Eigenvalue Analysis, the returned eigenvalue is real+imaginary. Hence, it errors out. If you make a comparison via punch file, you will see that in Normal Modes each node has 6 components and in Complex Eigen, there are 12 (real+imaginary)

$LABEL = Normal Mode
$EIGENVECTOR
$REAL OUTPUT
$SUBCASE ID = 3
$EIGENVALUE = 1.1001696E+04 MODE = 1
1 G 0.000000E+00 0.000000E+00 0.000000E+00
-CONT- 0.000000E+00 0.000000E+00 0.000000E+00

$LABEL = Complex EIGENVALUE
$EIGENVECTOR
$REAL-IMAGINARY OUTPUT
$SUBCASE ID = 1
$EIGENVALUE = ( -5.2379214E+00, 1.0501967E+02) MODE = 1
1 G 0.000000E+00 0.000000E+00 0.000000E+00
-CONT- 0.000000E+00 0.000000E+00 0.000000E+00
-CONT- 0.000000E+00 0.000000E+00 0.000000E+00
-CONT- 0.000000E+00 0.000000E+00 0.000000E+00

Hi Olcay,

Thanks for your reply. However, I already figured out why it does not work but I would like to know how to make it work.

If there are no modal assurance criteria function currently available in HS for evaluating complex eigenfrequencies, is there a workaround to extract just the damped eigenfrequencies (with the drawback that without MAC mode order may change during optimization)? 

Unless you can, somehow, manage to output eigenvalues in the same fashion of Normal Modes from OptiStruct (I am not sure if it is possible), there is currently no workaround. 

I was hoping for a solution, but thanks anyway.