*HEADING
: FINITE SLIDING CONTACT
VERIFICATION FOR FRICTION CHANGE
*AMPLITUDE,NAME=CONSTA
0,0.048,1,0.048
*AMPLITUDE,NAME=CONSTB
0,0.060,1,0.060
*AMPLITUDE,NAME=CONSTC
0,-0.064,1,-0.064
*NODE
1, 
7,7.5
*NGEN, NSET=E1
1,7
*NCOPY, OLDSET=E1, NEWSET=E2, SHIFT, CHANGE=20
0., 0., 2.5

*NFILL, NSET=BOT
E1,E2,2,10
*NCOPY, OLDSET=BOT, NEWSET=TOP, SHIFT, CHANGE=200
0.,2.,0.

*NFILL, NSET=BALL
BOT,TOP,2,100
*NODE
501, 0.5, 2.1, 0.25
503, 2.25, 2.1, 0.25
*NGEN, NSET=S1
501,503
*NCOPY, OLDSET=S1, NEWSET=S2, SHIFT, CHANGE=20
0., 0., 2.0

*NFILL, NSET=SLI_BOT
S1,S2,2,10
*NCOPY, OLDSET=SLI_BOT, NEWSET=SLI_TOP, SHIFT, CHANGE=200
0.,2.0,0.

*NFILL, NSET=SALL
SLI_BOT,SLI_TOP,2,100
*NSET, NSET=BC1
1,21,201,221
*NSET, NSET=NALL
BALL, SALL
*NMAP, NSET=NALL, TYPE=RECTANGULAR
0,0,0,.8,.0,.6
.48,.6,-.64
*TRANSFORM, NSET=NALL
.8,.0,.6,.48,.6,-.64
*ELEMENT, TYPE=C3D4
1, 1,21,3,201
2, 3,203,201,223
3, 21,201,221,223
4, 3,21,23,223
5, 3,201,21,223
*ELGEN, ELSET=BLOCK
1,3,2,5
2,3,2,5
3,3,2,5
4,3,2,5
5,3,2,5
*ELGEN
1,2,500,500
2,2,500,500
3,2,500,500
4,2,500,500
5,2,500,500
*ELSET, ELSET=SLIDER, GEN
501,505
*ELSET, ELSET=EALL
SLIDER, BLOCK
*SOLID SECTION, ELSET=EALL, MATERIAL=MAT
*MATERIAL, NAME=MAT
*ELASTIC
30.0E6, 0.3
*DENSITY
10.0, 
*ELSET, ELSET=BTOP,GEN
2,12,5
3,13,5
*ELSET, ELSET=SBOT
501,504
*surface, NAME=SL1
SBOT, S1
*surface, NAME=MA1
BTOP, S3
*CONTACT PAIR, INTERACTION=INT
SL1, MA1
*SURFACE INTERACTION, NAME=INT
*FRICTION
0.0, 
*BOUNDARY
BC1,1
BOT,2,3
SLI_TOP,3
*STEP, NLGEOM, INC=100, UNSYMM=YES
 FIRST COMPRESS
*STATIC, DIRECT
0.67,1.0
*CONTROLS, PARAMETER=FIELD
1.0E-6, 
*BOUNDARY
SLI_TOP,1
SLI_TOP,2,2,-.15
*EL PRINT, F=0
*NODE PRINT, F=0
*EL FILE,FREQ=5
S,E,
ELEN, 
*NODE FILE,FREQ=5
U,RF
*CONTACT FILE, MASTER=MA1
CSTRESS,CDISP
CAREA, 
CFN,CFS
CMN,CMS
CFT,CMT
XN,XS,XT
*END STEP
*STEP, NLGEOM, INC=100, UNSYMM=YES
 SLIDE ACROSS TOP - MODIFY FRICTION
*STATIC
0.1,1.0
*BOUNDARY
SLI_TOP,2,2,-.15
SLI_TOP,1,1,4.
*CHANGE FRICTION, INTERACTION=INT
*FRICTION
0.3, 
*END STEP
**
** step 4: Steady state dynamics, direct analysis
**
*STEP
*STEADY STATE DYNAMICS,DIRECT
20,100,5
*BOUNDARY,OP=NEW
BC1,1
BOT,2,3
SLI_TOP,1
SLI_TOP,2,2,0.1
SLI_TOP,3
*NODE FILE
U, 
RF, 
*EL FILE
E, 
S, 
*CONTACT FILE
*END STEP
**
** step 5: frequency extraction 
**
*STEP
*FREQUENCY,EIGENSOLVER=LANCZOS
28,,,1
*BOUNDARY
BC1,1
BOT,2,3
*BOUNDARY,BASE NAME=MOVA
 SLI_TOP,1,1
*BOUNDARY,BASE NAME=MOVB
 SLI_TOP,2,2
*BOUNDARY,BASE NAME=MOVC
 SLI_TOP,3,3
*CONTACT FILE,FREQ=0
*NODE FILE,F=0
*EL FILE,F=0
*MODAL FILE
*NODE PRINT,F=0
*EL PRINT,F=0
*END STEP
**
** step 6: Steady state dynamics, subspace projection
**
*STEP
*STEADY STATE DYNAMICS,SUBSPACE PROJECTION,INTERVAL=RANGE
20,100,5
*BASE MOTION,BASE NAME=MOVA,AMPLITUDE=CONSTA,DOF=1,TYPE=DISPLACEMENT
*BASE MOTION,BASE NAME=MOVB,AMPLITUDE=CONSTB,DOF=2,TYPE=DISPLACEMENT
*BASE MOTION,BASE NAME=MOVC,AMPLITUDE=CONSTC,DOF=3,TYPE=DISPLACEMENT
*NODE FILE
TU, 
RF, 
*EL FILE
E, 
S, 
*CONTACT FILE
*END STEP