*HEADING
AIRSPRING -- AXISYMMETRIC MODEL
*NODE
*NSET, NSET = CAVITY
*NGEN, LINE = C
**
** RUBBER SPRING
**
*ELEMENT, TYPE = SAX1
*ELGEN, ELSET = SPRING
*SHELL SECTION, COMPOSITE, ELSET = SPRING
2.5E-3, 3, RUBBER
1.0E-3, 3, STEEL
2.5E-3, 3, RUBBER
*MATERIAL, NAME = RUBBER
*HYPERELASTIC, POLYNOMIAL, N = 1
3.2E6, 0.8E6
*DENSITY
1000.,
*MATERIAL, NAME = STEEL
*ELASTIC, TYPE=LAMINA
2.48E9, 2.86E7, 9.105, 8.0E6, 8.0E6, 8.0E6
*DENSITY
7.8E3,
**
** RIGID BODY/SURFACE
**
*NODE, NSET = RIGID
*NODE,NSET=RIGNODE
*NGEN,NSET=RIGNODE,LINE=C
*ELEMENT,TYPE=RAX2,ELSET=RIGELEM
*ELGEN,ELSET=RIGELEM
*ELEMENT,TYPE=MASS,ELSET=MASS_RIGID
*MASS,ELSET=MASS_RIGID
.5,
*ELEMENT, TYPE = SAX1, ELSET = FLUID
*SHELL SECTION, ELSET=FLUID, MATERIAL=A1
1E-3,
*MATERIAL,NAME=A1
*ELASTIC
1E5, 0.1
*DENSITY
1.E-4,
*ELSET, ELSET=SPRINGSURF
*SURFACE, TYPE=ELEMENT, NAME=CAVSURF
SPRINGSURF, SPOS
*PHYSICAL CONSTANTS, ABSOLUTE ZERO=-273.16, UNIVERSAL GAS CONSTANT=8.314
**
**FLUID CAVITY DEFINITON
**
*FLUID CAVITY, NAME=SPRINGCAV, BEHAVIOR=GAS, REF NODE=500, SURFACE=CAVSURF, AMBIENT PRESSURE=101.36E+3
*FLUID BEHAVIOR, NAME=GAS
*MOLECULAR WEIGHT
*CAPACITY, TYPE=TABULAR
**
*BOUNDARY
1,1,3
4,1,6
6,1,1
RIGID,1,6
*NSET,NSET=RIG
*AMPLITUDE,NAME=RAMP,DEFINITION=SMOOTHSTEP
0.,0.,  .05,1.0
*NSET, NSET=QA_TEST_CAVITY
CAVITY,
*NSET, NSET=QA_TEST_RIGID
RIGID,
*SURFACE,TYPE=ELEMENT,NAME=ASURF,NOTHICK
ECON,SPOS
*SURFACE,TYPE=ELEMENT,NAME=BSURF
RIGELEM,SNEG
*RIGID BODY,REFNODE=11000,ELSET=RIGELEM
**
** STEP 1 - INFLATION STEP (5 ATMOSPHERES)
**
*STEP
*DYNAMIC,EXPLICIT, fixed
,.05
*RESTART,WRITE,NUMBER INTERVAL=1
*BOUNDARY,AMPLITUDE=RAMP
CAVITY,8,8, 5.066E5
**
** CONTACT DEFINITION
**
*ELSET,ELSET=ECON,GENERATE
*CONTACT PAIR,INTERACTION=SMOOTH
ASURF,BSURF
*SURFACE INTERACTION,NAME=SMOOTH
**
** OUTPUT REQUESTS
**
*ELSET,ELSET=EOUT
*OUTPUT, FIELD, TIME MARKS=YES, NUMBER INTER=2
*NODE OUTPUT, NSET=QA_TEST_RIGID
RF,
*OUTPUT, HIST, FREQ=1
*incrementation output
DT,
*ENERGY OUTPUT, VAR=all
*OUTPUT, HIST, FREQ=9999
*NODE OUTPUT, NSET=QA_TEST_CAVITY
PCAV, CVOL
***ENERGY OUTPUT, VAR=PRESELECT
*OUTPUT, FIELD, TIME MARKS=YES, NUMBER INTER=4
*NODE OUTPUT
U,
*DLOAD
SPRING,VP,1E4
*END STEP
**
** STEP 2 - SEAL CAVITY (KEEP RIGID SURFACE FIXED)
**          NONLINEAR LOAD DEFLECTION CURVE
**
*STEP
*DYNAMIC,EXPLICIT, fixed
,.05
*RESTART,WRITE,NUMBER INTERVAL=2
*BOUNDARY, OP=NEW,AMPLITUDE=RAMP
1,1,3
4,1,6
6,1,1
RIGID,1
RIGID,3,6
RIGID,2,2,-.075
*END STEP