*HEADING 
:  CONCENTRIC RINGS WITH INITIAL OVERCLOSURE [C3D8]
FINITE SLIDING (NLGEOM) BETWEEN CONTACT SURFACES
*NODE
41,4.7,0.0,0.0
73,4.7,0.0,0.0
*NODE
999,0.,0.
998,0.0,0.0,0.0
1,3.5,0.0,0.0
33,3.5,0.0,0.0
81,4.65,0.0
113,4.65,0.0
121,6.1,0.0
153,6.1,0.0
*NGEN,LINE=C,NSET=RAD_1
1,33,1,998,,,,0.0,0.0,1.0
*NGEN,LINE=C,NSET=RAD_2
41,73,1,998,,,,0.0,0.0,1.0
*NGEN,LINE=C,NSET=RAD_3
81,113,1,999,,,,0.0,0.0,1.0
*NGEN,LINE=C,NSET=RAD_4
121,153,1,999,,,,0.0,0.0,1.0
*NSET,NSET=INNODE
RAD_1,RAD_2,
*NSET,NSET=OUTNODE
RAD_3,RAD_4
*NCOPY,CHANGE NUMBER=500,OLD SET=INNODE,SHIFT,NEW SET=BACK
0.0,0.0,-1.5

*NCOPY,CHANGE NUMBER=500,OLD SET=OUTNODE,SHIFT,NEW SET=BACK
0.0,0.0,-1.5

*NSET,NSET=INNER,GEN
1,33,1
501,533,1
*NSET,NSET=BOUND,GEN
501,532,1
581,612,1
621,652,1
*ELEMENT,TYPE=C3D8
1,1,41,541,501,2,42,542,502
32,32,72,572,532,1,41,541,501
33,81,121,621,581,82,122,622,582
64,112,152,652,612,81,121,621,581
*ELGEN,ELSET=INELE
1,31,1,1,
*ELGEN,ELSET=OUTELE
33,31,1,1
*ELSET,ELSET=INELE,GEN
1,32,1
*ELSET,ELSET=OUTELE,GEN
33,64,1
*SOLID SECTION, ELSET=INELE, MATERIAL=MAT_1
*SOLID SECTION, ELSET=OUTELE, MATERIAL=MAT_2
*MATERIAL, NAME=MAT_2
*DENSITY
8.0100E-06, 
*ELASTIC, TYPE=ISO
206800.,.32
*MATERIAL, NAME=MAT_1
*DENSITY
8.0100E-06, 
*ELASTIC,TYPE=ISOTROPIC
206800.,.32
*surface,NAME=IN_SURF
INELE,S4
*surface,NAME=OUT_SURF
OUTELE,S6
*CONTACT PAIR,INTERACTION=FRIC,HCRIT=0.1,SMOOTH=0.25
IN_SURF,OUT_SURF
*SURFACE INTERACTION,NAME=FRIC
*BOUNDARY
INNER,1,2
BOUND,3,3
121,2,2
621,2,2
**
** RESOLVING INITIAL OVERCLOSURE
**
*STEP,NLGEOM,UNSYMM=YES
*STATIC
*EL PRINT,F=0
*NODE PRINT, F=0
*CONTACT FILE
CSTRESS,
*EL FILE
SP, 
SINV, 
*OUTPUT,FIELD
*ELEMENT OUTPUT
SP,
SINV, 
*CONTACT OUTPUT
CSTRESS,
*END STEP