*HEADING
: SIMPLE CONTACT TEST, 3-D SMALL SLIDING, DEFORMABLE, C3D8
** Contact Features Tested: 
**	*CONTACT INTERFERENCE, *FRICTION, *CHANGE FRICTION (mu=0 and mu=0.3),
**	*surface,type=node
*RESTART,WRITE, FREQ=4
*NODE,NSET=BOTTOM
1,0.,0.,8.,
3,1.,0.,8.,
9,1.,1.,8.
7,0.,1.,8.
*NODE,NSET=BSLID
21,0.,0.,10.,
23,1.,0.,10.,
27,0.,1.,10.
29,1.,1.,10.,
*NODE,NSET=TSLID
101,0.,0.,9.9
103,1.,0.,9.9
107,0.,1.,9.9
109,1.,1.,9.9
*NODE,NSET=TOP
121,0.,0.,11.9
123,1.,0.,11.9
127,0.,1.,11.9
129,1.,1.,11.9
*ELEMENT,TYPE=C3D8,ELSET=SOLID
1,1,3,9,7,21,23,29,27
3,101,103,109,107,121,123,129,127
*ELSET,ELSET=ETOP
3, 
*ELSET,ELSET=EBOT
1, 
*surface,type=node,NAME=ANSET
BSLID, 
*surface,NAME=BSURF
ETOP,S1
*CONTACT PAIR,INTERACTION=SLIDE,SMALL SLIDING
ANSET,BSURF
*SURFACE INTERACTION,NAME=SLIDE
*FRICTION
0., 
*SOLID SECTION,ELSET=SOLID,MATERIAL=SOLMAT
*MATERIAL,NAME=SOLMAT
*ELASTIC
30.E6,.0
*BOUNDARY
TOP,1,3
BOTTOM,1,3
**
** step 1: Shrink fit with *CONTACT INTERFERENCE.
** 	   Establish base state.
**
*STEP ,NLGEOM
*STATIC
0.25,1.
*CONTACT INTERFERENCE,SHRINK
ANSET,BSURF
*ENERGY FILE,FREQ=4
*CONTACT PRINT,SECONDARY=ANSET,MAIN=BSURF
*CONTACT FILE,SECONDARY=ANSET,MAIN=BSURF,F=4
*EL FILE ,FREQ=4
 S,
 E,
*NODE FILE,FREQ=4
 U,
 RF,
*ENERGY PRINT
*EL PRINT ,SUM=NO
 S,
 E,
*NODE PRINT,SUM=NO
 RF,
*END STEP
**
** step 2: slide top cube to the right w/o friction
**
*STEP,PERT
*STATIC
*BOUNDARY
TSLID,1,,0.1
TOP,1,,0.1
*ENERGY FILE,FREQ=6
*EL FILE ,FREQ=6
 S,
 E,
*NODE FILE,FREQ=6
 U,
 RF,
*CONTACT FILE,SECONDARY=ANSET,MAIN=BSURF,F=6
*ENERGY PRINT
*EL PRINT ,SUM=NO
 S,
 E,
*NODE PRINT,SUM=NO
 RF,
*END STEP
**
** step 3: change surface friction
**
*STEP,NLGEOM
*STATIC
1.0,1.0
*CHANGE FRICTION,INTERACTION=SLIDE
*FRICTION
0.3, 
*ENDSTEP
**
** step 4: slide to the left w/ friction
**
*STEP,PERT
*STATIC
*BOUNDARY
TSLID,1,,-0.1
TOP,1,,-0.1
*ENERGY FILE,FREQ=6
*EL FILE, FREQ=6
S,
E, 
*NODE FILE, FREQ=6
U, 
RF, 
*CONTACT FILE,SECONDARY=ANSET,MAIN=BSURF, FREQ=6
*CONTACT PRINT,SECONDARY=ANSET,MAIN=BSURF, FREQ=6
*PRINT,CONTACT=YES
*ENDSTEP