*HEADING
SIMPLE TESTS, FINITE SLIDING, [CGAX4, RAX2]               :-- 
**RESTART,WRITE, FREQ=30
*NODE
1,1.,5.
2,2.,5.
3,2.,10.
4,1.,10.
5,1.9,4.
6,1.9,15.
100, 2.9,7.5
*NSET, NSET=LT_N
1,4
*ELEMENT,TYPE=CGAX4,ELSET=LEFTEL
1,1,2,3,4
*ELEMENT,TYPE=RAX2, ELSET=RIGID
2,5,6
*SOLID SECTION,ELSET=LEFTEL,MATERIAL=SOLMAT
*MATERIAL,NAME=SOLMAT
*ELASTIC
30.E6,0.30
*RIGID BODY, ELSET=RIGID, REF NODE=100
*SURFACE INTERACTION,NAME=SLIDE
 1., 
*FRICTION, ANISOTROPIC
0.1,0.2
*surface,NAME=ASURF
LEFTEL,S2
*surface,NAME=RSURF
RIGID, SPOS
*CONTACT PAIR,INTERACTION=SLIDE
ASURF,RSURF
*BOUNDARY
LT_N,1,2
LT_N,5,5
100,1,6
**
**    step 1  :  interference fit, (radial intereference)
**
*STEP, INC=20, NLGEOM
           SHRINK FIT
*STATIC 
0.1,1.,0.1,0.2
*CONTACT INTERFERENCE,SHRINK
ASURF, RSURF
*NODE PRINT, F=0
*EL PRINT, F=0
*OUTPUT,FIELD,FREQ=0
*ELEMENT OUTPUT
*OUTPUT,FIELD,FREQ=0
*NODE OUTPUT
*OUTPUT,FIELD,FREQ=50
*CONTACT OUTPUT,VARIABLE=PRESELECT,SECONDARY=ASURF,MAIN=RSURF
*CONTACT PRINT, SECONDARY=ASURF , MAIN=RSURF, F=50
*ENDSTEP
**
**     step 2 : linear perturbation (about shrink fit); sliding upwards
**
*STEP,PERT,  NLGEOM
 PERT :- SLIDING UPWARDS
*STATIC
*BOUNDARY, OP=MOD
LT_N,2,,0.1
*NODE PRINT, F=0
*EL PRINT, F=0
*OUTPUT,FIELD,FREQ=0
*ELEMENT OUTPUT
*OUTPUT,FIELD,FREQ=0
*NODE OUTPUT
*OUTPUT,FIELD,FREQ=50
*CONTACT OUTPUT,VARIABLE=PRESELECT,SECONDARY=ASURF,MAIN=RSURF
*CONTACT PRINT, SECONDARY=ASURF , MAIN=RSURF, F=50
*ENDSTEP
**
**     step 3 : linear perturbation (about shrink fit); twist 
**
*STEP, PERT, NLGEOM
  PERT: TWISTING
*STATIC
*BOUNDARY, OP=MOD
LT_N,5,,0.1
*OUTPUT,FIELD,FREQ=50
*CONTACT OUTPUT,VARIABLE=PRESELECT,SECONDARY=ASURF,MAIN=RSURF
*CONTACT PRINT, SECONDARY=ASURF , MAIN=RSURF, F=50
*ENDSTEP
**
**     step 4: UNSYMM, linear perturbation, slide and twist
** 	          with shrink-fit base state.
**
*STEP,  PERT, NLGEOM, UNSYMM=YES
*STATIC
*BOUNDARY
LT_N,2,,0.1
LT_N,5,,0.1
*OUTPUT,FIELD,FREQ=50
*CONTACT OUTPUT,VARIABLE=PRESELECT,SECONDARY=ASURF,MAIN=RSURF
*CONTACT PRINT, SECONDARY=ASURF , MAIN=RSURF, F=50
*ENDSTEP
**
**       step 5: NLGEOM, UNSYMM, twist and sliding
**
*STEP, NLGEOM, UNSYMM=YES
*STATIC
0.1,1.0
*CONTROLS,PARAMETERS=FIELD
1.0E-6, 
*BOUNDARY
LT_N,2,,0.1
LT_N,5,,0.1
*ENDSTEP