Mechanical APDL Structural Analysis Guide

allsel,all

etable,seqv,s,eqv

pretab,seqv

finish

Example 9.3: Linear Perturbation Modal Analysis with Large Rotation Effects

*afun,deg

/prep7

/triad,lbot

/view,1,1,0,0

/angl,1,-90

/graph,full

rotxy=0

rotyz=0

rotzx=-90

et,1,185

n,1,0,0,0! Define nodes

n,2,.5,0,0

n,3,.5,1,0

n,4,0,1,0

ngen,11,10,1,4,1,0,0,1

en,1,1,2,3,4,11,12,13,14! Define elements

egen,10,10,1

mp,ex,1,1.0e6! define material

mp,ey,1,1.0e7

mp,ez,1,1.0e8

mp,nuxy,1,1.0e-8

mp,nuxz,1,1.0e-8

mp,nuyz,1,1.0e-8

mp,gxy,1,1e5

mp,gxz,1,1e5

mp,gyz,1,1e5

mp,dens,1,0.3/386.4

local,11,0,0,0,0,rotxy,rotyz,rotzx

csys,0

/psymb,cs,1

emodif,all,esys,11

tref,0

tunif,0

nsel,s,node,,1,4

d,all,ux,0

d,all,uy,0

d,all,uz,0

allsel,all

finish

!! Rigid rotation of 90 degrees

/solu

antype,static

nlgeom,on! large deflection

nsubst,1,1,1

save,case1,db,,model

nstep=9

dstep=90/nstep

*do,istep,1,nstep

theta=dstep*istep

nsel,s,node,,3,4

d,all,uz,-sin(theta)

d,all,uy,cos(theta)-1

allsel

solve

*enddo

finish

!! Linear perturbed modal analysis

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Example Inputs for Linear Perturbation Analysis