! This is the test case that I came up with for doing a PSD stress analysis.
! The stresses are either too large or too small when plotted.  How do you
! perform a basic PSD analysis and query the results?  It is not clear at all
! in the structural manual or the VM manuals.  There must be some material that
! is around that can outline the procedures and their basic underlying concepts.
! It would be most apprciated if you know of any reference materials that
! may use.  PS: I would like to see a training course and schedule listing
! for future dates.
!
!   THANKS! Jim Rinaldi
!           rinaldi@asheville.kearfott.com
!           (828) 686-3811 x307
!
FINISH
/CLEAR,START
!
/prep7
!
/units,bin
!
et,1,solid45
!
UIMP,1,EX, , ,29.4E6,           ! Material:  INCONEL 718
UIMP,1,DENS, , ,.286/386.4,
UIMP,1,NUXY, , ,0.29,
!
csys,0
!
k,,1.5,0.75,0
k,,0,0.75,0
k,,0,0.75,20
k,,0.5,0.75,20
!
k,,1.5,0,0
k,,0,0,0
k,,0,0,20
k,,0.5,0,20
!
v,1,2,3,4,5,6,7,8
!
lesize,2,,,25
lesize,4,,,25
lesize,8,,,25
lesize,12,,,25
!
lesize,3,,,2
lesize,9,,,2
lesize,10,,,2
lesize,11,,,2
!
lesize,1,,,2
lesize,5,,,2
lesize,6,,,2
lesize,7,,,2
!
mshkey,1
vmesh,1
!
nsel,s,loc,z,0
d,all,all
!
allsel,all
!
nsel,s,loc,x,0
dsym,symm,x,0
lplot
!
allsel,all
lplot
!
!



*go,:skip1

/TITLE,PSD Response of OGA Pump Assembly
!
/solu
!
antype,modal             ! perform a modal analysis
modopt,subsp,3           ! subspace iertation method
!eqslv,pcg                ! extract 2 modes from entire frequency range
mxpand,3,,,yes                 ! expand 2 modes, do element stress calculations
solve
!
*get,freq1,mode,1,freq
*get,freq2,mode,2,freq
*get,freq3,mode,3,freq
!
finish
!
/solu
antype,spectr            ! perform spectrum analysis
spopt,psd,2,yes           ! use first 2 modes from modal analysis

psdunit,1,accg           ! use g**2/hz for psd and dimension in inches
nsel,s,loc,z,0
d,all,uy,1.0               ! apply spectrum at the support point
allsel,all
psdfrq,1,,10.0,100.0    ! frequency range of 10 to 100 hertz
psdval,1,.1,.1           ! white noise psd, values in  g**2/hz
pfact,1,base             ! base excitation

dmprat,0.02              ! 2% damping
psdcom                   ! combine modes for psd, use default significance level

psdres,acel,rel          ! calculate relative acceleration solutions
solve
finish


:skip1