How can I make a strain energy distribution plot for a PSD analysis? We tried using an ETABLE item with (ETABLE,name,SENE), but we could not plot it.


Not all the usual result quantities are available after a psd analysis. Only the component displacements and stresses are available. Derived quantities like strain energy are not available because they cannot be computed from the unsigned one-sigma component results. An approximate method is to perform a /POST1 ETABLE combination of the modal results factored by the PSD modal coefficients.

Here is an example. Since the variance retrieved with *GET is the square of the mode coefficient and the strain energy is a product of stress and strain, the *GET value can be used directly since the mode coefficient needs to be applied twice.


/prep7
et,1,42
mp,ex,1,1e7
mp,nuxy,1,.3
mp,dens,1,.00025
rect,,20,,1.5
esize,1
amesh,1
nsel,s,loc,x,0
d,all,all
nsel,all
fini

/solu
antyp,modal
modop,lanb,5
mxpand,5,,,yes
solve
fini

/solu
antyp,spectrum
spopt,psd,,yes
psdfrq,1,,1,1000
psdval,1,1,1
nsel,s,loc,x,0
d,all,uy,1
nsel,all
pfact,1
psdcom
solve
fini

/post1
*get,q11,mode,1,mcoef
*get,q22,mode,2,mcoef
*get,q33,mode,3,mcoef

set,1,1
etab,sene_m1,sene
etab,volu,volu
sexp,send_m1,sene_m1,volu,1,-1

set,1,2
etab,sene_m2,sene
sexp,send_m2,sene_m2,volu,1,-1

set,1,3
etab,sene_m3,sene
sexp,send_m3,sene_m3,volu,1,-1

sadd,send_tot,send_m1,send_m2,q11,q22 ! add modes 1 and 2
sadd,send_tot,send_tot,send_m3,1,q33 ! add mode 3 to total
pretab,send_tot





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