/COM,ANSYS MEDIA REL. 2025R1 (11/08/2024) REF. VERIF. MANUAL: REL. 2025R1
/verify,vm275
/title,vm275,Mode lock-in and friction induced vibration on a Pin-Disc Model
/com,
/com, This verification manual highlights the mode coupling
/com, phenomenon on a pin-disc set up using brake squeal analysis.
/com, The brake squeal analysis is performed using all 3 methods
/com,
/com, Reference:
/com, Allgaier, R., Gaul, L., Keiper, W., Willner, K., Mode Lock-In
/com, and Friction Modeling, Computational Methods in Contact
/com, Mechanics IV,ed. By L. Gaul and C.A. Brebbia, WIT Press,
/com, Southampton (1999), pg 35-47
/com,
/output,scratch ! Redirect output to Scratch file
/prep7
et,1,solid186 ! Solid186
keyopt,1,2,1 ! Full Integration
type,1
mp,ex,1,70000
mp,dens,1,2.7e-9
mp,nuxy,1,0.33
cylind,8,179,-12.5,12.5,0,90 ! Model Disc
lsel,s,line,,9,12,1
lesize,all,,,3
lsel,all
lsel,s,line,,1,8,7
lsel,a,line,,3,6,3
lesize,all,,,12
lsel,all
lsel,s,line,,2,7,5
lsel,a,line,,4,5,1
lesize,all,,,12
lsel,all
vsweep,all
vsymm,x,all
vsymm,y,all
nummrg,node
nummrg,kp
allsel,all
csys,1
nsel,s,loc,x,8
d,all,all,0 ! Constrain the inner radius of Disc
allsel,all
csys,0
local,11,0,0,0,12.5,0,0,4
csys,11
k,100,0,167.00,0.00
k,101,0,157.00,0.00
k,102,-10.00,157.00,0.00
k,103,-10.00,167.00,0.00
k,104,0,167.00,0.00+149
k,105,0,157.00,0.00+149
k,106,-10.00,157.00,0.00+149
k,107,-10.00,167.00,0.00+149
a,100,101,102,103
a,104,105,106,107
a,100,101,105,104
a,103,102,106,107
a,100,104,107,103
a,101,105,106,102
va,12,17,23,24,25,26 ! Modeling Pin
ET,2,solid186
keyopt,2,2,1
TYPE,2
mat,1
ESIZE,5
VMESH,5
ALLSEL,ALL
vsel,s,volume,,5
eslv,s
nsle,s
nrotate,all
allsel,all
csys,0
et,3,conta175 ! Defining Frictional Contact Pair
mp,mu,3,0.152 ! Coefficient of Friction
keyopt,3,2,0 ! Augumented Lagrangian
keyopt,3,9,2 ! Include penetration or gap with ramped effects
keyopt,3,10,0 ! Update contact stiffness each iteration
keyopt,3,12,0 ! Standard Contact
et,4,targe170
r,3
rmodif,3,3,1 ! Normal penalty stiffness factor
rmodif,3,5,0 ! Initial contact closure
rmodif,3,6,1 ! Pin ball region
rmodif,3,10,0 ! Contact surface offset
rmodif,3,12,0 ! Tanget penalty stiffness factor
type,3
real,3
mat,3
asel,s,area,,12
nsla,s,1
esln,s
esurf
allsel,all
type,4
real,3
asel,s,area,,2,20,6
nsla,s,1
esln,s
esurf
allsel,all
esel,s,type,,4
cm,tar,elem ! Forming a component with target elements
allsel,all
save,vm275,db
finish
/com, *******************************************************
/com, Full Nonlinear Perturbed Modal Analysis
/com, ********************************************************
/solu
antype,static
nlgeom,on ! Nonlinear analysis
nropt,unsym ! Newton-Raphson with unsymmetric matrices
rescontrol,define,all,1
asel,s,area,,17
nsla,s,1
d,all,ux,0
d,all,uy,0
d,all,uz,-0.1 ! Displacement load to bring Pin and Disc
allsel,all ! to contact
time,1
autots,on
nsubs,10,20,1
solve ! 1st Load Step
time,2.0
cmrot,tar,,,2.0 ! Rotate the nodes of target element
autots,on ! to generate sliding friction contact
solve ! 2nd Load Step
finish
/solu
antype,static,restart,,,perturb ! Restarting from last load step and sub step
perturb,modal,,,
solve,elform ! Reform the matrices
modopt,unsym,30,500,4000, ! Solving using UNSYM eigensolver
mxpand,30,,,
cntr,out,yes ! redirect contact echo to '.cnm file'
/out,
solve
fini
/post1
file,,rstp
set,1,7,,IMAG
*get,unstablemode1,active,0,set,freq
*stat,unstablemode1
*dim,label,char,1,2
*dim,value,,1,3
label(1,1)='Mode'
*vfill,value(1,1),data,2215 ! Unstable mode from Reference
*vfill,value(1,2),data,unstablemode1 ! Results obtained from MAPDL
*vfill,value(1,3),data,abs(2215/unstablemode1) ! Ratio
save,table_1
finish
/delete,,rstp
/delete,,rst
/clear,nostart
/com, *******************************************************
/com, Partial Nonlinear Perturbed Modal Analysis
/com, *******************************************************
/out,scratch
/prep7
resume,vm275,db
finish
/solu
antype,static
nlgeom,on ! Nonlinear analysis
nropt,unsym ! Newton-Raphson with unsymmetric matrices
rescontrol,define,all,1
asel,s,area,,17
nsla,s,1
d,all,ux,0
d,all,uy,0
d,all,uz,-0.1 ! Displacement load to bring Pin and Disc
allsel,all ! to contact
time,1
autots,on
nsubs,10,20,1
solve ! 1st Load Step
finish
/solu
antype,static,restart,,,perturb ! Restarting from last load step and sub step
perturb,modal,,,
cmrot,tar,,,2.0 ! Rotate the nodes of target element
! to generate sliding friction contact
solve,elform ! Reform the matrices
modopt,unsym,30,500,4000, ! Solving using UNSYM eigensolver
mxpand,30,,,
cntr,out,yes ! redirect contact echo to '.cnm file'
/out,
solve
fini
/post1
file,,rstp
set,1,7,,IMAG
*get,unstablemode2,active,0,set,freq
*stat,unstablemode2
*dim,label,char,1,2
*dim,value,,1,3
label(1,1)='Mode'
*vfill,value(1,1),data,2215 ! Unstable mode from Reference
*vfill,value(1,2),data,unstablemode2 ! Results obtained from MAPDL
*vfill,value(1,3),data,abs(2215/unstablemode2) ! Ratio
save,table_2
finish
/delete,,rstp
/delete,,rst
/clear,nostart
/com, *******************************************************
/com, Linear Non-prestressed Modal Analysis
/com, *******************************************************
/output,scratch
/prep7
resume,vm275,db
allsel,all
asel,s,area,,17
nsla,s,1
d,all,ux,0
d,all,uy,0
d,all,uz,0.0
allsel,all
finish
/solu
antype,modal
nropt,unsym ! Newton-Raphson with unsymmetric matrices
cmrot,tar,,,2.0 ! Rotate the nodes of target element
! to generate sliding friction contact
modopt,unsym,30,500,4000, ! Solving using UNSYM eigensolver
mxpand,30,,,
cntr,out,yes ! redirect contact echo to '.cnm file'
/out,
solve
fini
/post1
file,,rst
set,1,7,,IMAG
*get,unstablemode3,active,0,set,freq
*stat,unstablemode3
*dim,label,char,1,2
*dim,value,,1,3
label(1,1)='Mode'
*vfill,value(1,1),data,2215 ! Unstable mode from Reference
*vfill,value(1,2),data,unstablemode3 ! Results obtained from MAPDL
*vfill,value(1,3),data,abs(2215/unstablemode3) ! Ratio
save,table_3
finish
resume,table_1
/com,
/out,vm275,vrt
/com,
/com, ------------------------------VM275 RESULTS COMPARISON----------------------
/com,
/com, | TARGET | Mechanical APDL | RATIO
/com,
/com,
/com, Full Nonlinear Perturbed Modal Analysis
/com,
*VWRITE,LABEL(1,1),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A14,' ',F12.3,' ',F12.3,' ',F12.3)
/com,
/com,
/NOPR,
resume,table_2
/GOPR
/com,
/com,
/com, Partial Nonlinear Perturbed Modal Analysis
/com,
*VWRITE,LABEL(1,1),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A14,' ',F12.3,' ',F12.3,' ',F12.3)
/com,
/com,
/NOPR,
resume,table_3
/GOPR
/com,
/com,
/com, Linear Non-prestressed Modal Analysis
/com,
*VWRITE,LABEL(1,1),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A14,' ',F12.3,' ',F12.3,' ',F12.3)
/com,
/com,
/NOPR,
/com,
/com,
/com, --------------------------------------------------------------------------------
/out,
*list,vm275,vrt
/delete,table_1
/delete,table_2
/delete,table_3
finish
