Learning Forum

[Thomas Schneider]

Good morning,

i have a script APDL which create the spectrum in one direction, but the damping ratio is applied in DMPRAT,0.04 and also in SV,0.04,....

But i wanted to made the same thing in workbench, with a modale and spectrale modulus, but in the script, i saw that the damping ratio is not applied in the SV, only the DMPRAT command.

i would like to know which one is better ? if i need to explicit the value twice, or only with DMPR or SV ? and what is the point to use one and not the other ? Which way is the right way ? 😵

For the context, i made my analyse modal-spectral with a script APDL, and i would like to stoping use my script and use workbench, but i didn't got the same results, the only way is to delete the damping ratio in the SV command.

Thank you in advance.

[dlooman]

The damping ratio value on the SV command is only used when there are multiple spectrums specified with different damping values.  For example, there might be a spectrum based on 2% damping and SV,.02 would be specified for it.  A spectrum based on 5% damping would have SV,.05.  In APDL the damping specified with dmpr will be used to interpolate between the spectrums.  Since damping is already accounted for in the spectrums, it doesn't have the usual effect of damping the results.  It does affect the coupling coefficients of certain combination methods.  Mechanical doesn't have the capability to specify multiple spectrums so the damping input on the SV command doesn't apply to it.