## Structural Dynamics

#### Do you have any tests verifying force excitation PSD by comparison to the more common base excitation PSD?

• Solution
Participant

SR 1323472733 Yes, the inputs below give the same solution for force and base excitation when one force is used. Thereâ€™s no comparison possible when multiple forces are used. ! base excitation /prep7 et,1,188 mp,ex,1,1e7 mp,dens,1,.0003 mp,nuxy,1,.03 sectype,1,beam,rect secdata,.4,.2 et,2,21 r,2,1e6,1e6,1e6 n,1 n,11,20 fill e,1,2 *repe,10,1,1 d,1,all d,11,all fini /solu antype,modal modop,lanb,24 mxpand,all,,,yes solve fini /solu antype,spectrum spopt,psd,,yes d,1,uy,1 psdunit,1,acel psdres,disp,abs psdfrq,1,,1,10,100,1000 psdval,1,1000,1000,1000,1000 pfact,1 psdcom solve fini /post1 set,3,1 prdi prrsol etab,sbyt,smisc,32 etab,sbzt,smisc,34 pretab,sbyt,sbzt fini ! force excitation /prep7 et,1,188 mp,ex,1,1e7 mp,dens,1,.0003 mp,nuxy,1,.03 sectype,1,beam,rect secdata,.4,.2 et,2,21 r,2,1e6,1e6,1e6 n,1 n,11,20 fill e,1,2 *repe,10,1,1 type,2 real,2 e,1 d,1,all ddele,1,uy d,11,all fini /solu antype,modal modop,lanb,24 mxpand,all,,,yes solve fini /solu antype,spectrum spopt,psd,,yes f,1,fy,1e6 psdunit,1,forc psdfrq,1,,1,10,100,1000 psdval,1,1000,1000,1000,1000 pfact,1,node psdcom solve fini save /post1 set,3,1 prdi prrsol etab,sbzt,smisc,34 etab,sbyt,smisc,32 pretab,sbzt,sbyt

Attachments:
1. 2034964.zip