Shock response spectrum analysis

[Torben Faurholdt]

Hello everybody

I am doing SRS analysis using the:

*FREQUENCY_DOMAIN_RESPONSE_SPECTRUM
$#   mdmin     mdmax     fnmin     fnmax    restrt     mcomb    relatv
         1        80       0.0    1000.0                   0         1
$#   dampf    lcdamp     ldtyp    dmpmas    dmpstf
      0.03         0         0       0.0       0.0

         1         1      2001       0.0         0         0         1         0

Are there any restrictions to the use of solid elements in this type of analysis. I am using tetreahedral elements number 17 in combination with shell elements, number 16. I can run the simulation but the results comming out in the d3spcm file looks like som sort of noise. When using only shell elements everything look fine. 

Anybody know that could be the cause of this?