*HEADING 
CONCENTRIC RINGS WITH INITIAL OVERCLOSURE [C3D8R]
3D SOFTENED CONTACT WITH NO SEPARATION AND CONTACT DAMPING 
USING A DAMPING COEFFICIENT
*NODE
41,4.7,0.0,-0.01
73,4.7,0.0,-0.01
*NODE
999,0.,0.
998,0.0,0.0,-0.01
1,3.5,0.0,-0.01
33,3.5,0.0,-0.01
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,-1.48

*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=C3D8R
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
*NSET,NSET=ALL,ELSET=INELE
*NSET,NSET=ALL,ELSET=OUTELE
*BOUNDARY
INNER,1,2
BOUND,3,3
ALL,3,3
121,2,2
621,2,2
137,2,2
637,2,2
*NSET,NSET=NODERES,ELSET=INELE
*NSET,NSET=NODERES,ELSET=OUTELE
*SURFACE,NAME=IN_SURF
INELE,S4
*SURFACE,NAME=OUT_SURF
OUTELE,S6
**
** RESOLVING INITIAL OVERCLOSURE
**
*STEP
*DYNAMIC, EXPLICIT
,1.E-2
*CONTACT PAIR,INTERACTION=NOFRIC,WEIGHT=1.0
OUT_SURF,IN_SURF
*SURFACE INTERACTION,NAME=NOFRIC, PAD THICKNESS=-5.0E-02
*SURFACE BEHAVIOR, PRESSURE-OVERCLOSURE=TABULAR,NO SEPARATION
0.0,-5.0E-02
1.0E3,0.0
*CONTACT DAMPING, DEFINITION=CRITICAL DAMPING FRACTION
1.0,
**
** Output requests for postprocessing
**
*OUTPUT,FIELD,VAR=PRESELECT
**
** Output requests for qa testing
**
*ELSET,ELSET=QA_TESTEL
17,18,19,49,50,51
*NSET,NSET=QA_TESTN,ELSET=QA_TESTEL
*OUTPUT,FIELD,NUMBER=1
*NODE OUTPUT,NSET=QA_TESTN
U,
*OUTPUT,HISTORY,TIME INTERVAL=0.005
*ENERGY OUTPUT,VAR=PRESELECT
*END STEP