Chandra Sekaran
Ansys Employee

You need to indicate which nodes are going to be excited before issuing PFACT command. IF all the fixed nodes are going to be excited, say, in X direction by the PSD then you can use the below and then use the PFACT.

ksel,r,kp,,1,4,1
nslk,r,n,all
d,all,ux,1   
allsel,all
pfact,1,base

 

 

antype,spectrum,new
spopt,psd,alles,no
!EFINIZIONE SPETTRO DI RISPOSTA DELLA STRUTTURA
PSDUNIT,1,accg,9.81
psdfrq,1,,10,40,500
psdval,1,0.078,0.078,0.0078
sed,0.0,1.0,0.0
allsel,all
pfact,1,base