*HEADING
 : *MODEL CHANGE verification for ISL21A contact element
*NODE
1,0.0,7.5
7,0.0,0.0
11,2.0,7.5
17,2.0,0.0
101,2.1,2.25
103,2.1,0.5
111,4.1,2.25
113,4.1,0.5
21,0.0,7.5
27,0.0,0.0
31,2.0,7.5
37,2.0,0.0
121,2.1,2.25
123,2.1,0.5
131,4.1,2.25
133,4.1,0.5
*NGEN,NSET=BASE
1,7,2
*NGEN,NSET=BASER
21,27,2
*NGEN
111,113
*NGEN
131,133
*NSET,NSET=TOP
111,113
*NSET,NSET=TOPR
131,133
*NGEN
11,17,2
101,103
31,37,2
121,123
*ELEMENT,TYPE=CAX4,ELSET=STEEL
1,1,3,13,11
11,101,103,113,111
21,21,23,33,31
31,121,123,133,131
*ELGEN,ELSET=STEEL
1,3,2
21,3,2
*ELEMENT,TYPE=ISL21A,ELSET=SLIDE1
 101, 101,103
*INTERFACE,ELSET=SLIDE1
*FRICTION
0.2, 
*ELEMENT,TYPE=ISL21A,ELSET=SLIDE1R
 121, 121,123
*INTERFACE,ELSET=SLIDE1R
*FRICTION
0.2, 
*SOLID SECTION,ELSET=STEEL,MATERIAL=STEEL
*MATERIAL,NAME=STEEL
*ELASTIC
 30.E6,0.3
*SLIDE LINE,TYPE=LINEAR,ELSET=SLIDE1,SMOOTH=0.1
 11,13,15,17
*SLIDE LINE,TYPE=LINEAR,ELSET=SLIDE1R,SMOOTH=0.1
 31,33,35,37
*ELEMENT, TYPE=MASS, ELSET=REF
9999, 112
99999,132
*MASS, ELSET=REF
1.0e-5,
*EQUATION
3,
112, 2, 1.0,   111, 2, -0.5,  113, 2, -0.5,  
3,
132, 2, 1.0,   131, 2, -0.5,  133, 2, -0.5,  
**********
**
**
**
*STEP,UNSYMM=YES
  CONTACT -- Push top element down
*STATIC
 0.67,1.
*CONTROLS,PARAMETERS=FIELD
1.0E-6, 
*BOUNDARY
BASE,1
1,2
11,2
TOP,1,,-.15
111,2
BASER,1
21,2
31,2
TOPR,1,,-.15
131,2
*PRINT,CONTACT=YES
*EL PRINT,FREQ=50
S,E
*NODE PRINT,FREQ=50
U,RF
*EL FILE,FREQ=50
S,E
*NODE FILE,FREQ=50
U,RF
*END STEP
**
**
*STEP,UNSYMM=YES
  Slide Top Across
*STATIC
 1.,10.,1.
*BOUNDARY,OP=NEW
BASE,1
1,2
11,2
TOP,1,,-.15
111,2,,4.
BASER,1
21,2
31,2
TOPR,1,,-.15
131,2,,4.
*END STEP
**
**
**
*STEP, UNSYMM=YES
 Remove contact condition
*STATIC
1,10,1
*model change,remove
 slide1,
*BOUNDARY,OP=NEW
BASE,1
1,2
11,2
TOP,1,,-.15
111,2,,4.
BASER,1
21,2
31,2
TOPR,1,,-.099999
131,2,,4.
*END STEP
**
**
**
*STEP, UNSYMM=YES,INC=50
 reactivate contact gradually with contact interference
 The overclosure is not greater than 0.05
*STATIC
.1,10,.1
*model change,add
 slide1,
*contact interfer,type=element
 slide1, 0.05
*BOUNDARY,OP=NEW
BASE,1
1,2
11,2
TOP,1,,-.15
111,2,,4.
BASER,1
21,2
31,2
TOPR,1,,-.15
131,2,,4.
*END STEP
**