The following example shows a harmonic analysis with unbalanced force using the component mode synthesis (CMS) procedure on a rotating part. It illustrates the use of the SYNCHRO command and whirl animation using the ANHARM command during postprocessing.
The structure is a two-spool rotor on symmetric bearings as shown in Figure 7.12: Multi-Spool Rotor Model (Full and CMS Model). The outer spool rotates at up to 5000 RPM and the inner spool rotates about twice as fast.
This model is also used in Example: Unbalance Harmonic Analysis. In the following example, however, the inner spool is reduced to a CMS superelement.
An unbalanced force is applied at a node on the outer spool and the harmonic response is calculated.
/out,
/com, ******************************************
/com, Multi-Spool CMS Model
/com, ******************************************
/out,scratch
/filname,cms_model
/prep7
et,1,281
type,1
sectype,1,shell
secdata,0.05/2,1,0,3
mp,ex,1,2.0e11
mp,dens,1,7800
mp,nuxy,1,0.3
mat,1
k,1,0,0.15,0
k,2,0,0.20,0
k,3,3,0.20,0
k,4,3,0.15,0
k,5,0,0,0
k,6,10,0,0
a,1,2,3,4
vrotat,1,,,,,,5,6,360
lsel,s,line,,2,8,2
lsel,a,line,,22,24,2
lsel,a,line,,14,16,2
lesize,all,,,6
lsel,all
lsel,s,line,,9,12,1
lsel,a,line,,17,20,1
lsel,a,line,,25,32,1
lesize,all,,,4
lsel,all
lsel,s,line,,1,7,2
lsel,a,line,,13,15,2
lsel,a,line,,21,23,2
lesize,all,,,1
lsel,all
amesh,all
allsel,all
et,3,281
type,3
secnum,3
mat,1
sectype,3,shell
secdata,0.05/2,1,0,7
k,35,7,0.20,0
k,36,7,0.15,0
k,37,10,0.15,0
k,38,10,0.20,0
a,35,36,37,38
vrotat,21,,,,,,5,6,360
lsel,s,line,,34,40,2
lsel,a,line,,54,56,2
lsel,a,line,,46,48,2
lesize,all,,,6
lsel,all
lsel,s,line,,57,64,1
lsel,a,line,,41,44,1
lsel,a,line,,49,52,1
lesize,all,,,4
lsel,all
lsel,s,line,,33,39,2
lsel,a,line,,45,47,2
lsel,a,line,,53,55,2
lesize,all,,,1
lsel,all
amesh,21,40,1
allsel,all
nummrg,node
nummrg,kp
numstr,node,3000
numstr,elem,3000
et,2,281
mp,ex,2,2.0e11
mp,dens,2,7800
mp,nuxy,2,0.3
mp,alpd,2,1e-3 ! Material damping
mp,betd,2,1e-4
type,2
secnum,2
mat,2
sectype,2,shell
secdata,0.1/2,1,0,5
k,39,3,0.20,0
k,40,3,0.30,0
k,41,7,0.30,0
k,42,7,0.20,0
a,39,40,41,42
vrotat,41,,,,,,5,6,360
lsel,s,line,,66,72,2
lsel,a,line,,78,80,2
lsel,a,line,,86,88,2
lesize,all,,,8
lsel,s,line,,89,96,1
lsel,a,line,,81,84,1
lsel,a,line,,73,76,1
lesize,all,,,4
lsel,s,line,,65,71,2
lsel,a,line,,77,79,2
lsel,a,line,,85,87,2
lesize,all,,,1
amesh,41,60,1
allsel,all
cpintf,all
et,4,214
keyopt,4,2,1
keyopt,4,3,0
real,4
r,4,1.0e6,1.4e5,,,10,10
rmore,,,,
n,10000,5,0.22,0
type,4
real,4
e,node(5,0.20,0),10000
allsel,all
esel,s,type,,1
cm,comp1,elem
esel,all
esel,s,type,,2
cm,comp2,elem
esel,all
esel,s,type,,3
cm,comp3,elem
esel,all
nsel,s,loc,x,0
nsel,a,loc,x,10
d,all,all,0
nsel,all
d,10000,all,0
nsel,s,loc,x,0
cm,interface1,node
allsel,all,all
nsel,s,loc,x,3
cm,interface2,node
allsel,all,all
nsel,s,loc,x,7
cm,interface3,node
allsel,all,all
nsel,s,loc,x,10
cm,interface4,node
allsel,all,all
save
fini
/clear,nostart
/filname,model
/prep7
et,1,281
type,1
sectype,1,shell
secdata,0.05/2,1,0,3
mp,ex,1,2.0e11
mp,dens,1,7800
mp,nuxy,1,0.3
k,1,0,0.15,0
k,2,0,0.20,0
k,3,3,0.20,0
k,4,3,0.15,0
k,5,0,0,0
k,6,10,0,0
a,1,2,3,4
vrotat,1,,,,,,5,6,360
lsel,s,line,,2,8,2
lsel,a,line,,22,24,2
lsel,a,line,,14,16,2
lesize,all,,,6
lsel,all
lsel,s,line,,9,12,1
lsel,a,line,,17,20,1
lsel,a,line,,25,32,1
lesize,all,,,4
lsel,all
lsel,s,line,,1,7,2
lsel,a,line,,13,15,2
lsel,a,line,,21,23,2
lesize,all,,,1
lsel,all
amesh,all
allsel,all
et,3,281
type,3
secnum,3
mat,1
sectype,3,shell
secdata,0.05/2,1,0,7
k,35,7,0.20,0
k,36,7,0.15,0
k,37,10,0.15,0
k,38,10,0.20,0
a,35,36,37,38
vrotat,21,,,,,,5,6,360
lsel,s,line,,34,40,2
lsel,a,line,,54,56,2
lsel,a,line,,46,48,2
lesize,all,,,6
lsel,all
lsel,s,line,,57,64,1
lsel,a,line,,41,44,1
lsel,a,line,,49,52,1
lesize,all,,,4
lsel,all
lsel,s,line,,33,39,2
lsel,a,line,,45,47,2
lsel,a,line,,53,55,2
lesize,all,,,1
lsel,all
amesh,21,40,1
allsel,all
nummrg,kp
nummrg,node
esel,s,type,,1
cm,comp1,elem
esel,all
esel,s,type,,2
cm,comp2,elem
esel,all
esel,s,type,,3
cm,comp3,elem
esel,all
nsel,s,loc,x,0
cm,interface1,node
allsel,all,all
nsel,s,loc,x,3
cm,interface2,node
allsel,all,all
nsel,s,loc,x,7
cm,interface3,node
allsel,all,all
nsel,s,loc,x,10
cm,interface4,node
allsel,all,all
save
fini
!generation pass
/filname,part1
/sol
antype,substr
seopt,part1,3,1
cmsopt,fix,10
cmomega,comp1,1
coriolis,on,,,on ! Coriolis on in a stationary reference frame
cmsel,s,comp1
cmsel,s,interface2
m,all,all
nsle
cmsel,s,interface1
m,all,all
nsle
solve
allsel,all,all
fini
save
/filname,part2
/sol
antype,substr
seopt,part2,3,1
cmsopt,fix,10
cmomega,comp3,1
coriolis,on,,,on ! Coriolis on in a stationary reference frame
cmsel,s,comp3
cmsel,s,interface3
m,all,all
nsle
cmsel,s,interface4
m,all,all
nsle
solve
fini
save
!use pass
/clear,nostart
/filname,use
!/out,
/prep7
et,1,matrix50
type,1
se,part1
se,part2
numstr,node,3000
numstr,elem,3000
et,2,281
sectype,2,shell
secdata,0.1/2,1,0,5
mp,ex,1,2.0e11
mp,dens,1,7800
mp,nuxy,1,0.3
mp,alpd,1,1e-3 ! Material damping
mp,betd,1,1e-4
type,2
mat,1
secnum,2
k,5,0,0,0
k,6,10,0,0
k,19,3,0.20,0
k,20,3,0.30,0
k,21,7,0.30,0
k,22,7,0.20,0
a,19,20,21,22
vrotat,1,,,,,,5,6,360
lsel,s,line,,2,8,2
lsel,a,line,,14,16,2
lsel,a,line,,22,24,2
lesize,all,,,8
lsel,all
lsel,s,line,,9,12,1
lsel,a,line,,17,20,1
lsel,a,line,,25,32,1
lesize,all,,,4
lsel,all
lsel,s,line,,1,7,2
lsel,a,line,,13,15,2
lsel,a,line,,21,23,2
lesize,all,,,1
lsel,all
nummrg,kp
amesh,1,20,1
allsel,all
nsel,s,loc,x,3
nsel,a,loc,x,7
cpintf,all
allse,all,all
et,4,214
keyopt,4,2,1
keyopt,4,3,0
real,4
r,4,1.0e6,1.4e5,,,10,10
rmore,,,,
n,10000,5,0.22,0
type,4
real,4
e,node(5,0.20,0),10000
allsel,all
nsel,s,loc,x,0
nsel,a,loc,x,10
d,all,all,0
nsel,all
d,10000,all,0
esel,s,type,,1
cm,comp1,elem
allsel,all,all
esel,s,type,,2
cm,comp2,elem
allsel,all,all
save
fini
/com, ******************************************
/com, Solution Controls for Full Harmonic Solve
/com, ******************************************
/solu
antype,harmic ! Perform Harmonic analysis
hropt,full
F0 = 1.0e-4 ! Unbalance Force
n3 = node(5.0,-0.29424,0.58527e-1)
f,n3,fy,-F0 ! Real FY component at node 'nodeUnb'
f,n3,fz,,F0 ! Imaginary FZ component at node 'nodeUnb'
cmomega,comp1,1000
cmomega,comp2,500
coriolis,on,,,on ! Coriolis on in a stationary reference frame
synchro,,comp2
dmprat,0.02 ! Global damping ratio
spinRpm1 = 0
spinRpm2 = 7200
begin_freq = spinRpm1/60 ! Begin frequency of excitation
end_freq = spinRpm2/60 ! End frequency of excitation
harfrq,begin_freq,end_freq
nsubs,120
kbc,1
solve
finish
/post1
file,use,rst
set,last
/show,jpeg
/graphics,power
/eshape,1
plnsol,u,sum
*get,umax,plnsol,0,max
/show,close
/out,
*stat,umax
/out,scratch
fini
!expansion pass
/clear,nostart
/filname,part1
resume,part1,db
/solu
expass,on
seexp,part1,use
numexp,all,,,yes
solve
fini
/clear,nostart
/filname,part2
resume,part2,db
/solu
expass,on
seexp,part2,use
numexp,all,,,yes
solve
fini
/inquire,test,exist,final,rst
*if,test,eq,1,then
/delete,final,rst
*endif
/clear,nostart
resume,cms_model,db
/post1
*do,j,1,120
file,part1 ! generation pass 1 rst file
append,1,j
file,part2 ! generation pass 1 rst file
append,1,j
file,use ! generation pass 1 rst file
append,1,j
reswrite,final,,,,1
file,part1 ! generation pass 1 rst file
append,1,j,,1
file,part2 ! generation pass 1 rst file
append,1,j,,1
file,use ! generation pass 1 rst file
append,1,j,,1
reswrite,final,,,,1
*enddo
fini
/post1
file,final,rst
set,last
/show,jpeg
/graphics,power
/eshape,1
plnsol,u,sum
*get,umax,plnsol,0,max
plesol,s,eqv
*get,smax,plnsol,0,max
plesol,epel,eqv
*get,emax,plnsol,0,max
/show,close
/out,
*stat,umax
*stat,smax
*stat,emax
/out,scratch
plnsol,u,sum
anharm,12,0.1,,,3, ! Full Harmonic
fini
/post26
file,final,rst
n1 = node(5.0,0.58527e-1,0.29424)
n2 = node(5.0,0.29424,-0.58527e-1)
/com ************************************************************************
/com, Output: Amplitude at nodes %n1% and %n2% as a function of the frequency
/com ************************************************************************
nsol,2,n1,U,Y,UY
nsol,3,n1,U,Z,UZ
realvar,4,2,,,UYR
realvar,5,3,,,UZR
prod,6,4,4,,UYR_2
prod,7,5,5,,UZR_2
add,8,6,7,,UYR_2+UZR_2
sqrt,9,8,,,AMPL%n1%
extreme
nsol,2,n2,U,Y,UY
nsol,3,n2,U,Z,UZ
realvar,4,2,,,UYR
realvar,5,3,,,UZR
prod,6,4,4,,UYR_2
prod,7,5,5,,UZR_2
add,8,6,7,,UYR_2+UZR_2
sqrt,10,8,,,AMPL%n2%
extreme
/com *****************
/com, Graphics display
/com *****************
/gropt,logy,1
/show,jpeg
/title,'Unbalance Response Analysis using CMS Model'
!/yrange,1.0e-5,1.0e+2
/out,
plvar,9,10 ! Displays variables in the form of a graph
/show,close
!prvar,9,10
finish
/exit,nosave
The results of the unbalanced response analysis, postprocessed in /POST26, are shown in Figure 7.13: Unbalanced Response Using CMS Model and Figure 7.14: Unbalanced Response Using Full Model. The logarithmic plots show the variation of the displacement amplitudes of two selected nodes with respect to the frequency of excitation.
The animation of the whirls is shown below.
