*HEADING
 SPRING, DASHPOT, MASS ELEMENTS: MODEL CHANGE VERIFICATION
*PREPRINT,MODEL=YES,HISTORY=NO
**
** TEST 1: SPRING/DASHPOT/MASS
**
*NODE,NSET=NALL
1,  0.0, 1.
2,  1.0, 1.
3,  2.0, 1.
11, 0.0, 0.
12, 1.5, -.1
13, 3.0, -.3
*NSET,NSET=LEFT
1,11
*NSET,NSET=MID
12, 
*NSET,NSET=RIGHT
13, 
*NSET,NSET=TIP
3,13
*ELEMENT,TYPE=SPRINGA,ELSET=SPRINGA
1, 1,2
2, 2,3
11,11,12
12,12,13
*ELEMENT,TYPE=SPRING1,ELSET=SPRING1
3,2
4,3
13,12
14,13
*ELEMENT,TYPE=DASHPOTA,ELSET=DASHPOTA
101, 1,2
102, 2,3
111,11,12
112,12,13
*ELEMENT,TYPE=DASHPOT1,ELSET=DASHPOT1
103,2
104,3
113,12
114,13
*ELEMENT,TYPE=MASS,ELSET=MASS
201, 2
202, 3
211, 12
212, 13
*MASS,ELSET=MASS
10., 
*SPRING,ELSET=SPRINGA,NONLINEAR

-2.0, -.3
 0.0,  .0
 1.0, .05
 2.0, .15
 3.0,  .4
*SPRING,ELSET=SPRING1,NONLINEAR
2, 
-2.0, -.3
 0.0,  .0
 1.0, .05
 2.0, .10
 3.0, .20
*DASHPOT,ELSET=DASHPOTA,NONLINEAR
 , 
 -2.000, -2.00
  2.000,  2.00
*DASHPOT,ELSET=DASHPOT1,NONLINEAR
2 , 
 -2.000, -2.00
  2.000,  2.00
*ELSET,ELSET=TEST
11,12,13,14
*ELSET,ELSET=TESTDASH
111,112,113,114,211,212
*AMPLITUDE,NAME=RAMP
0.,0., .5,1.0
**
**
*STEP,NLGEOM
 STEP #1: DISPLACE TEST SPECIMEN SO FINAL SHAPE IS
          IDENTICAL TO INITIAL SHAPE OF REFERENCE ELEMENT 
*STATIC
0.25,1.
*PRINT,MODEL CHANGE=YES
*BOUNDARY,AMP=RAMP
NALL,3
LEFT,1,6
RIGHT,1,1,-1.0
RIGHT,2,2, 0.3
MID,1,1,-0.5
MID,2,2, 0.1
*NODE PRINT,FREQ=999
RF, 
*EL PRINT,POSITION=CENTROID,FREQ=999
1,
S,E
*OUTPUT,FIELD,FREQ=999
*ELEMENT OUTPUT
1,
S,
*OUTPUT,FIELD,FREQ=999
*NODE OUTPUT
RF, 
*ELEMENT OUTPUT,POSITION=CENTROID
1,
E,S,
*OUTPUT,HISTORY,FREQ=999
*NODE OUTPUT, NSET=NALL
RF, 
*END STEP
**
**
*STEP,NLGEOM
 STEP #2: REMOVE TEST ELEMENTS
*STATIC
1.,1.
*MODEL CHANGE,REMOVE,TYPE=ELEMENT
TEST,
TESTDASH,
*BOUNDARY,OP=NEW
LEFT,1,6
*END STEP
**
**
*STEP,NLGEOM
 STEP #3: APPLY LOAD TO BOTH ELEMENTS AND 
 ADD TEST ELEMENTS BACK IN STRAIN-FREE
*STATIC
0.25,1.
*MODEL CHANGE,ADD=STRAINFREE,TYPE=ELEMENT
TEST,
TESTDASH,
*BOUNDARY,AMP=RAMP,TYPE=VELOCITY
3,1,1,.3
3,2,2,.3
13,1,1,.3
13,2,2,.3
*END STEP
**
**
*STEP,NLGEOM
 STEP #4: REMOVE TEST ELEMENT
*STATIC
.25,1.0
*BOUNDARY,OP=NEW,FIXED
NALL,1,3
*MODEL CHANGE,REMOVE,TYPE=ELEMENT
TEST,
*END STEP
**
**
*STEP,NLGEOM
 STEP #5: ADD TEST ELEMENTS BACK IN WITH-STRAIN
*STATIC
.25,1.0
*MODEL CHANGE,ADD=WITHSTRAIN,TYPE=ELEMENT
TEST,
*END STEP
**
**
*STEP,NLGEOM
 STEP #6: FREQUENCY EXTRACTION
*FREQUENCY, eigensolver=lanczos, SIM=NO
8, , 
*BOUNDARY,OP=NEW
LEFT,1,6
*EL PRINT,FREQ=0
*NODE PRINT,FREQ=0
*OUTPUT,FIELD,FREQ=0
*END STEP
**
**
*STEP,PERTURBATION
 STEP #7: MODAL DYNAMIC
*MODAL DYNAMIC
.5,5.
*CLOAD
TIP,1,2.5
*NODE PRINT,FREQ=999
RF, 
*EL PRINT,POSITION=CENTROID,FREQ=999
S,E
*OUTPUT,FIELD,FREQ=999
*NODE OUTPUT
RF, 
*OUTPUT,HISTORY,FREQ=999
*NODE OUTPUT, NSET=NALL
RF, 
*OUTPUT,FIELD,FREQ=999
*ELEMENT OUTPUT
S, 
*OUTPUT,FIELD,FREQ=999
*ELEMENT OUTPUT,POSITION=CENTROID
E, 
S, 
*END STEP
**
**
*STEP,PERTURBATION
 STEP #8: STEADY-STATE DYNAMICS, MODAL BASED
*STEADY STATE DYNAMICS,INTERVAL=RANGE
.05,.5,5
*CLOAD
TIP,1,2.5
*NODE PRINT,FREQ=999
RF, 
*EL PRINT,POSITION=CENTROID,FREQ=999
S,E
*OUTPUT,FIELD,FREQ=999
*NODE OUTPUT
RF, 
*OUTPUT,HISTORY,FREQ=999
*NODE OUTPUT, NSET=NALL
RF, 
*OUTPUT,FIELD,FREQ=0
*ELEMENT OUTPUT,POSITION=CENTROID
*END STEP
**
**
*STEP,PERTURBATION
 STEP #9: STEADY-STATE DYNAMICS, DIRECT
*STEADY STATE DYNAMICS,DIRECT
.05,.5,5
*BOUNDARY,OP=NEW
LEFT,1,6
*CLOAD
TIP,1,2.5
*NODE PRINT,FREQ=999
RF, 
*EL PRINT,POSITION=CENTROID,FREQ=999
S,E
*OUTPUT,FIELD,FREQ=999
*NODE OUTPUT
RF, 
*OUTPUT,HISTORY,FREQ=999
*NODE OUTPUT,NSET=NALL
RF, 
*OUTPUT,FIELD, FREQ=0
*ELEMENT OUTPUT,POSITION=CENTROID
*END STEP
**
**
*STEP,PERTURBATION
 STEP #10: STEADY-STATE DYNAMICS, SUBSPACE PROJECTION
*STEADY STATE DYNAMICS,SUBSPACE PROJECTION,INTERVAL=RANGE
.05,.5,5
*CLOAD
TIP,1,2.5
*NODE PRINT,FREQ=999
RF, 
*EL PRINT,POSITION=CENTROID,FREQ=999
S,E
*OUTPUT,FIELD,FREQ=999
*NODE OUTPUT
RF, 
*OUTPUT,HISTORY,FREQ=999
*NODE OUTPUT,NSET=NALL
RF, 
*OUTPUT,FIELD, FREQ=0
*ELEMENT OUTPUT,POSITION=CENTROID
*END STEP
**
**
*STEP,NLGEOM
 STEP #11: DYNAMICS
*DYNAMIC
.5,5.
*BOUNDARY,OP=NEW
LEFT,1,6
*EL PRINT,POSITION=CENTROID,FREQ=999
S,E
*NODE PRINT,FREQ=999
RF, 
*CLOAD
TIP,1,2.5
*END STEP