*HEADING
 FRIC_COEF USER SUBROUTINE VERIFICATION 
*RESTART,WRITE,FREQ=0
*NODE, NSET=NALL
   1, 0., 0.
   2, 0., 1.
   3, 1., 0.
   4, 1., 1.
 100, 0., 0.
*ELEMENT,TYPE=B21,ELSET=BEAM
 1, 1,2
 2, 3,4
*BEAM SECTION,SECT=CIRC,ELSET=BEAM,MATERIAL=ELAS,TEMP=GRADIENTS
 0.564189584,
 0.,0.,-1.,
*MATERIAL,NAME=ELAS
*ELASTIC
 30.E6,0.3
*RIGID BODY,ANALYTICAL SURFACE=RS1,REFNODE=100
*surface,TYPE=SEGMENTS,NAME=RS1
 START,-10.,0.
 LINE,10.,0.
*SURFACE,TYPE=NODE,NAME=CN1
 1,
*SURFACE,TYPE=NODE,NAME=CN2
 3,
*CONTACT PAIR,INTERACTION=CI1
 CN1,RS1
*CONTACT PAIR,INTERACTION=CI2
 CN2,RS1
*SURFACE INTERACTION,NAME=CI1
 1.0,
*FRICTION,LAG
 0.00,	0   ,	 0    ,	 0
 0.00,	100 ,    0    ,  0
 1.00,	0   ,    1000 ,  0
 0.98,	1   ,    1000 ,  0
 0.89,	5   ,    1000 ,  0
 0.80,	10  ,    1000 ,  0
 0.64,	25  ,    1000 ,  0
 0.54,	50  ,    1000 ,  0
 0.50,	100 ,    1000 ,  0
 0.40,	0   ,    0    ,  200
 0.39,	1   ,    0    ,  200
 0.36,	5   ,    0    ,  200
 0.32,	10  ,    0    ,  200
 0.26,	25  ,    0    ,  200
 0.22,	50  ,    0    ,  200
 0.20,	100 ,    0    ,  200
 1.40,	0   ,    1000 ,  200
 1.37,	1   ,    1000 ,  200
 1.25,	5   ,    1000 ,  200
 1.12,	10  ,    1000 ,  200
 0.90,	25  ,    1000 ,  200
 0.76,	50  ,    1000 ,  200
 0.70,	100 ,    1000 ,  200
**
*SURFACE INTERACTION,NAME=CI2
 1.0,
*FRICTION,USER=COEF,PROP=5,LAG
 0.001, 5e-4, 0.002, 0.001,0.05
*INITIAL CONDITION,TYPE=TEMPERATURE
 1, 20.0
 2, 20.0
 3, 20.0
 4, 20.0
*AMPLITUDE,NAME=AMP1
 0.0, 0.0, 0.2, 0.0625, 0.4, 0.1250, 0.6, 0.2500,
 0.8, 0.5, 1.0, 1.0
**
** STEP 1: ESTABLISH CONTACT (PRESCRIBED DISPLACEMENT)
**
*STEP, NLGEOM, UNSYM=YES
 ESTABLISH CONTACT (PRECRIBED DISPLACEMENT)
*STATIC
 1.,1.
*BOUNDARY
 100,1,2,0.0
 100,6,6,0.0
 2,1,1,0.0
 2,2,2,-1.e-5
 2,6,6,0.0
 4,1,1,0.0
 4,2,2,-1.e-5
 4,6,6,0.0
*PRINT,CONTACT=YES
*OUTPUT,FIELD,FREQ=1
*CONTACT OUTPUT,VARIABLE=PRESELECT,SECONDARY=CN1,MAIN=RS1
*CONTACT OUTPUT,VARIABLE=PRESELECT,SECONDARY=CN2,MAIN=RS1
*CONTACT PRINT,F=1,SECONDARY=CN1,MAIN=RS1
*CONTACT PRINT,F=1,SECONDARY=CN2,MAIN=RS1
*END STEP
**
** STEP 2: ESTABLISH CONTACT (APPLY NORMAL PRESSURE = 300)
**
*STEP, NLGEOM
 ESTABLISH CONTACT (APPLY NORMAL PRESSURE = 300)
*STATIC
 1.,1.
*BOUNDARY,OP=NEW
 100,1,2,0.0
 100,6,6,0.0
 2,1,1,0.0
 2,6,6,0.0
 4,1,1,0.0
 4,6,6,0.0
*CLOAD
 2,2,-300.0
 4,2,-300.0
*END STEP
**
** STEP 2: APPLY SHEAR  
**
*STEP, NLGEOM
 APPLY SHEAR 
*STATIC
 .1,1.,,.1
*BOUNDARY,OP=NEW
 100,1,2,0.0
 100,6,6,0.0
 2,6,6,0.0
 4,6,6,0.0
*BOUNDARY,OP=NEW,AMP=AMP1
 2,1,1,0.05
 4,1,1,0.05
*CLOAD, OP=NEW
 2,2,-450.0
 4,2,-450.0
*TEMPERATURE
 2, 50.0
 4, 50.0 
*END STEP