*HEADING
: LINEAR BEHAVIOR OF SPRING AND DASHPOT ELEMENTS
[SPRING2, SPRINGA, DASHPOT2, DASHPOTA] 
*PREPRINT, MODEL=YES, HISTORY=YES
*RESTART,WRITE,OVERLAY
*********************************************
** Define one spring/dashpot 
** systems to be analyzed simultaneously
*********************************************
*NODE,NSET=NALL
11,0.,10.
12,10.,10.
13,20.,10.
*NODE,NSET=TRANS
101,0.,20.
102,10.,30.
103,20.,40.
*NODE
14,  10.0, 0.0
104, 20.0, 0.0
*NSET,NSET=NALL
TRANS, 
*TRANSFORM,NSET=TRANS,TYPE=R
1.,1.,0.,-1.,1.,0.
**
** Spring Definitions
**
*ELEMENT,TYPE=SPRING2,ELSET=SPR2
2,12,11
3,13,12
*ELEMENT,TYPE=SPRINGA,ELSET=SPRA
4,102,101
5,103,102
*ELEMENT, TYPE=SPRINGA, ELSET=SPR
101, 14, 104
*ELEMENT, TYPE=MASS, ELSET=MS
102, 104
**
** Dashpot Definitions
**
*ELEMENT,TYPE=DASHPOT2,ELSET=DSH2
7,13,12
*ELEMENT,TYPE=DASHPOTA,ELSET=DSHA
8,103,102
**
** Point Masses
**
*ELEMENT,TYPE=MASS,ELSET=MA
10,12
11,13
12,102
13,103
*NSET,NSET=MASSES
2,12,13,102,103
**
** Property Definitions
**
*ORIENTATION,NAME=TRANS,DEFINITION=COORDINATES
1.,1.,0.,-1.,1.,0.
*SPRING,ELSET=SPR2
1,1
30.0, 
*SPRING,ELSET=SPRA,ORIENTATION=TRANS

30.0, 
*SPRING, NONLINEAR, ELSET=SPR

 10,  0.1
 30,  0.2
*DASHPOT,ELSET=DSH2
1,1
0.12, 
*DASHPOT,ELSET=DSHA,ORIENTATION=TRANS

0.12, 
*MASS,ELSET=MA
0.02588, 
*MASS, ELSET=MS
4.0e-11, 
**
****************************
** Analysis
****************************
**
****************************
** Test Elements
**	SPRING2,DASHPOT2
****************************
**
** ---------------- STEP 3
**
*STEP
  STRETCH OUT 
*STATIC
1.E2,1.E2
*BOUNDARY,OP=NEW
** Fix mid mass and Stretch end mass of spr2 and sprA systems
11,1,6
101,1,6
12,1,6
102,1,6
13,1,1,1.
13,2,6
103,1,1,1.
103,2,6
14, 1, 6, 0.0
104, 1, 1,0.0
*EL PRINT, FREQ=2,SUMMARY=NO
S, 
E, 
*NODE PRINT,FREQ=2,SUMMARY=NO,GLOBAL=NO
U, 
V, 
A, 
CF, 
RF, 
*NODE FILE,NSET=NALL,FREQ=10,GLOBAL=NO
U , V , A
*OUTPUT,FIELD,FREQ=10
*NODE OUTPUT,NSET=NALL
U,V,A
*EL FILE,FREQUENCY=10
S,E
*OUTPUT,FIELD,FREQ=10
*ELEMENT OUTPUT
S,E
*END STEP
*****************************
** Release Stretched System
*****************************
***
** ---------------- STEP 4
**
*STEP,INC=10000
 RELEASE
*DYNAMIC,HAFTOL=0.1
5.E-9,0.7,1.E-9,0.7
*BOUNDARY,OP=NEW
**
** Removed previous BC's.  Now we add all but
** those belonging to the mass nodes, so they
** are free to move.
**
11,1,6
101,1,6
14, 1, 6, 0.0
104, 1, 6, 0.0
*NODE FILE,NSET=NALL,FREQ=1,GLOBAL=NO
U,V,A
*OUTPUT,FIELD,FREQ=1
*NODE OUTPUT,NSET=NALL
U,V,A
*EL FILE,FREQ=50
S,E
*OUTPUT,FIELD,FREQ=50
*ELEMENT OUTPUT
S,E
*END STEP
***************************
** Do a dummy dynamic step to 
** to check if nonlinear behavior of
** spring is correctly accounted for
**v53_810
***************************
*STEP, INC=10000, AMPLITUDE=RAMP
*DYNAMIC, HAFTOL=0.01
0.1e-04, 0.1,,0.1
*BOUNDARY, OP=MOD
14,  1, 6, 0.0
104, 1, 1, 0.15
*EL PRINT, FREQ=9999, ELSET=SPR
S, 
*END STEP