*HEADING
: SIMPLE CONTACT TEST, SMALL SLIDING, CPS4
** Contact Features Tested: 
**	*CONTACT INTERFERENCE w/SHRINK, *FRICTION, 
**      *CHANGE FRICTION (mu=0 and mu=0.3)
**      BOTH FRICTION STEPS ARE PERTURBATION STEPS
** Dynamic Features Tested:
**      *STEADY STATE DYNAMICS,DIRECT
**      *FREQUENCY,EIGENSOLVER=LANCZOS
**      *STEADY STATE DYNAMICS,SUBSPACE PROJECTION
*AMPLITUDE,NAME=CONST
0,1,1,1
*RESTART,WRITE, FREQ=4
*NODE, Nset=ODB_NSET
1,
2,1.,
3,1.,1.2,
4,,1.2
11,-1.,1.
12,2.,1.
13,2.,3.
14,-1.,3.
*ELEMENT,TYPE=CPS4,ELSET=BOT
1,1,2,3,4
*ELEMENT,TYPE=CPS4,ELSET=TOP
11,11,12,13,14
*SOLID SECTION,ELSET=TOP,MATERIAL=MAT
*SOLID SECTION,ELSET=BOT,MATERIAL=MAT
*MATERIAL,NAME=MAT
*ELASTIC
1.E5,0.
*DENSITY
10.0, 
*surface,NAME=TOPS
TOP,S1
*surface,NAME=BOTS
BOT,S3
*SURFACE INTERACTION,NAME=ISLS
1.0, 
*FRICTION
0., 
*CONTACT PAIR,INTERACTION=ISLS, SMALL SLIDING
BOTS,TOPS
*BOUNDARY
1,1,2
2,1,2
13,1,2
14,1,2
**
** step 1: Shrink fit with *CONTACT INTERFERENCE.
** 	   Establish base state.
**
**
** Sets added by addodb
**
*Elset,Elset=ODB_ESET
TOP, BOT
**
**
*Nset, Nset=ODB_NSET
ODB_NSET,
**
**
*STEP,INC=20,NLGEOM
*STATIC
0.2,1.,0.2,0.2
*CONTACT INTERFERENCE, SHRINK
BOTS,TOPS
*EL FILE
S, 
*NODE FILE
U, 
RF, 
*CONTACT FILE,SLAVE=BOTS,MASTER=TOPS
*CONTACT PRINT,SLAVE=BOTS,MASTER=TOPS
*PRINT,CONTACT=YES
*OUTPUT,FIELD,VARIABLE=PRESELECT,OP=ADD,FREQUENCY=4
*OUTPUT,FIELD, OP=ADD
*ELEMENT OUTPUT
S, 
*OUTPUT,HISTORY,OP=ADD
*ELEMENT OUTPUT, Elset=ODB_ESET
S, 
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT
U, 
RF, 
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT, Nset=ODB_NSET
U, 
RF, 
*OUTPUT,FIELD, OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL,SLAVE=BOTS,MASTER=TOPS
*OUTPUT,HISTORY,OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL,SLAVE=BOTS,MASTER=TOPS
*END STEP
**
** step 2: slide to the right w/o friction, linear perturbation
**
*STEP,PERT,NLGEOM
*STATIC
*BOUNDARY,OP=MOD
1,1,,0.1
2,1,,0.1
*EL FILE
S, 
*NODE FILE
U, 
*CONTACT FILE,SLAVE=BOTS,MASTER=TOPS
*CONTACT PRINT,SLAVE=BOTS,MASTER=TOPS
*PRINT,CONTACT=YES
*OUTPUT,FIELD, OP=ADD
*ELEMENT OUTPUT
S, 
*OUTPUT,HISTORY,OP=ADD
*ELEMENT OUTPUT, Elset=ODB_ESET
S, 
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT
U, 
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT, Nset=ODB_NSET
U, 
*OUTPUT,FIELD, OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL,SLAVE=BOTS,MASTER=TOPS
*OUTPUT,HISTORY,OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL,SLAVE=BOTS,MASTER=TOPS
*END STEP
**
** step 3: change surface friction
**
*STEP,NLGEOM
*STATIC
1.0,1.0
*CHANGE FRICTION,INTERACTION=ISLS
*FRICTION
0.3, 
*END STEP
**
** step 4: slide to the left w/ friction, linear perturbation
**
*STEP,NLGEOM,PERT
*STATIC
*BOUNDARY
1,1,,-0.1
2,1,,-0.1
*EL FILE
S, 
*NODE FILE
U, 
RF, 
*CONTACT FILE,SLAVE=BOTS,MASTER=TOPS
*CONTACT PRINT,SLAVE=BOTS,MASTER=TOPS
*PRINT,CONTACT=YES
*OUTPUT,FIELD, OP=ADD
*ELEMENT OUTPUT
S, 
*OUTPUT,HISTORY,OP=ADD
*ELEMENT OUTPUT, Elset=ODB_ESET
S, 
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT
U, 
RF, 
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT, Nset=ODB_NSET
U, 
RF, 
*OUTPUT,FIELD, OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL,SLAVE=BOTS,MASTER=TOPS
*OUTPUT,HISTORY,OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL,SLAVE=BOTS,MASTER=TOPS
*END STEP
**
** step 5: Steady state dynamics, direct analysis
**
*STEP
*STEADY STATE DYNAMICS,DIRECT
4,20,5
*BOUNDARY
1,2,,0.01
2,2,,0.01
*NODE FILE
U, 
RF, 
*EL FILE
E, 
S, 
*CONTACT FILE
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT
U, 
RF, 
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT, Nset=ODB_NSET
U, 
RF, 
*OUTPUT,FIELD, OP=ADD
*ELEMENT OUTPUT
E, 
S, 
*OUTPUT,HISTORY,OP=ADD
*ELEMENT OUTPUT, Elset=ODB_ESET
E, 
S, 
*OUTPUT,FIELD, OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL
*OUTPUT,HISTORY,OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL
*END STEP
**
** step 6: frequency extraction ->all modes are extracted
**
*STEP
*FREQUENCY,EIGENSOLVER=LANCZOS
4,0,,, 
*BOUNDARY,BASE NAME=SHAKE
1,2,2
2,2,2
*CONTACT FILE,FREQ=0
*MODAL FILE
*NODE FILE,F=0
*EL FILE,F=0
*NODE PRINT,F=0
*EL PRINT,F=0
*OUTPUT,FIELD,Frequency=0
*OUTPUT,HISTORY,Frequency=0
*OUTPUT,FIELD
*node output
U,
*END STEP
**
** step 7: Steady state dynamics, direct analysis
**
*STEP
*STEADY STATE DYNAMICS,SUBSPACE PROJECTION,INTERVAL=RANGE
4,20,5
*BASE MOTION,BASE NAME=SHAKE,AMPLITUDE=CONST,DOF=2,TYPE=DISPLACEMENT,SCALE=0.01
*NODE FILE
U, 
RF, 
*EL FILE
E, 
S, 
*MODAL FILE
BM, 
*CONTACT FILE
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT
U, 
RF, 
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT, Nset=ODB_NSET
U, 
RF, 
*OUTPUT,FIELD, OP=ADD
*ELEMENT OUTPUT
E, 
S, 
*OUTPUT,HISTORY,OP=ADD
*ELEMENT OUTPUT, Elset=ODB_ESET
E, 
S, 
*OUTPUT,FIELD, OP=ADD
*MODAL OUTPUT,VARIABLE=ALL
BM, 
*OUTPUT,FIELD, OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL
*OUTPUT,HISTORY,OP=ADD
*CONTACT OUTPUT, VARIABLE=ALL
*END STEP