*HEADING
: SIMPLE CONTACT TEST, SMALL SLIDING, CAXH4
** Contact Features Tested:
**	*CONTACT INTERFERENCE, *FRICTION, *CHANGE FRICTION (mu=0 and mu=0.3)
** SLIDING STEPS ARE PERTURBATION STEPS
*RESTART,WRITE, FREQ=4
*NODE
*ELEMENT,TYPE=CAX4H,ELSET=BOTEL
*ELEMENT,TYPE=CAX4H,ELSET=TOPEL
*ELSET,ELSET=SOLID
BOTEL,TOPEL
*SOLID SECTION,ELSET=SOLID,MATERIAL=SOLMAT
*MATERIAL,NAME=SOLMAT
*ELASTIC
30.E6,0.
*SURFACE INTERACTION,NAME=SLIDE
 1.,
*FRICTION
0.,
*surface,NAME=BOTS
BOTEL,S3
*surface,NAME=TOPS
TOPEL,S1
*CONTACT PAIR,INTERACTION=SLIDE, SMALL SLIDING
BOTS,TOPS
*BOUNDARY
1,1,2,0.
2,1,2,0.
7,1,2,0.
8,1,2,0.
**
** step 1: Shrink fit with *CONTACT INTERFERENCE.
** 	   Establish base state.
*STEP,INC=20,NLGEOM
*STATIC
0.2,1.,0.2,0.2
*CONTACT INTERFERENCE,SHRINK
BOTS,TOPS
*OUTPUT,FIELD
*ELEMENT OUTPUT
S,
*OUTPUT,FIELD
*NODE OUTPUT
U,
*OUTPUT,FIELD
*CONTACT OUTPUT,VARIABLE=PRESELECT,SLAVE=BOTS,MASTER=TOPS
*CONTACT PRINT,SLAVE=BOTS,MASTER=TOPS
*PRINT,CONTACT=YES
*ENDSTEP
**
** step 2: slide radially out w/o friction, linear perturbation
**	   with shrink-fit base state.
**
*STEP,PERT,NLGEOM
*STATIC
1.0,1.0
*BOUNDARY,OP=MOD
7,1,,0.1
8,1,,0.1
5,1,,0.1
6,1,,0.1
*OUTPUT,FIELD
*ELEMENT OUTPUT
S,
*OUTPUT,FIELD
*NODE OUTPUT
U,
*OUTPUT,FIELD
*CONTACT OUTPUT,VARIABLE=PRESELECT,SLAVE=BOTS,MASTER=TOPS
*CONTACT PRINT,SLAVE=BOTS,MASTER=TOPS
*PRINT,CONTACT=YES
*ENDSTEP
**
** step 3: change surface friction
**
*STEP
*STATIC
1.0,1.0
*CHANGE FRICTION,INTERACTION=SLIDE
*FRICTION
0.3,
*ENDSTEP
**
** step 4: slide radially in w/ friction, linear perturbation
** 	   with shrink-fit base state.
**
*STEP,NLGEOM,PERT
*STATIC
*BOUNDARY
7,1,,-0.1
8,1,,-0.1
5,1,,-0.1
6,1,,-0.1
*OUTPUT,FIELD
*ELEMENT OUTPUT
S,
*OUTPUT,FIELD
*NODE OUTPUT
U,
*OUTPUT,FIELD
*CONTACT OUTPUT,VARIABLE=PRESELECT,SLAVE=BOTS,MASTER=TOPS
*CONTACT PRINT,SLAVE=BOTS,MASTER=TOPS
*PRINT,CONTACT=YES
*ENDSTEP