*HEADING
: MODEL CHANGE ACOUSTICS TESTS  [AC3D4]
*PREPRINT,ECHO=YES,MODEL=YES,HISTORY=YES
*NODE, Nset=ODB_NSET
1, 
41,,10.
1001,1.
1041,1.,10.
2001,,,1.
2041,,10.,1.
3001,1.,,1.
3041,1.,10.,1.
*NGEN,NSET=ALL_NODES
1,41
1001,1041
2001,2041
3001,3041
*ELEMENT,TYPE=AC3D4,ELSET=ALL_ELEMENTS
    1,    1,    3, 2003, 1001
    2,    3, 2003, 1001, 1003
    3, 2003, 1001, 1003, 3003
    4,    1, 2003, 2001, 1001
    5, 2003, 2001, 1001, 3003
    6, 2001, 1001, 3003, 3001
*ELGEN,ELSET=ALL_ELEMENTS
1,20,2,6
2,20,2,6
3,20,2,6
4,20,2,6
5,20,2,6
6,20,2,6
*ELSET,ELSET=SECOND,GENERATE
61,120
*MATERIAL,NAME=AIR
*DENSITY
1.293, 
*ACOUSTIC MEDIUM,BULK MODULUS
1.42176E5, 
*SOLID SECTION,MATERIAL=AIR,ELSET=ALL_ELEMENTS
*NSET,NSET=RECRD,GEN
1,21
*NSET,NSET=DRIV
1,1001,2001,3001
**************************************
*Elset,Elset=ODB_ESET
SECOND, ALL_ELEMENTS
**
**
*Nset, Nset=ODB_NSET
ODB_NSET, ALL_NODES, RECRD, DRIV
**
**
*STEP
*STEADY STATE DYNAMIC,DIRECT
1., 
*IMPEDANCE
120,I2,
118,I4,
*BOUNDARY
DRIV,8,,1.
*NODE PRINT,NSET=RECRD
POR,PPOR
*NODE FILE,NSET=RECRD
POR,PPOR
*OUTPUT,FIELD,VARIABLE=PRESELECT,OP=ADD,FREQUENCY=9999
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT,NSET=RECRD
POR,
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT,NSET=RECRD
POR,
*ENDSTEP
**************************************
*STEP
*STATIC
1,1
*MODEL CHANGE,REMOVE
SECOND,
*ENDSTEP
**************************************
*STEP
*STEADY STATE DYNAMIC,DIRECT
1., 
*IMPEDANCE,OP=NEW
60,I2,
58,I4,
*BOUNDARY
DRIV,8,,1.
*NODE PRINT,NSET=RECRD
POR,PPOR
*NODE FILE,NSET=RECRD
POR,PPOR
*OUTPUT,FIELD, OP=ADD
*NODE OUTPUT,NSET=RECRD
POR,
*OUTPUT,HISTORY,OP=ADD
*NODE OUTPUT,NSET=RECRD
POR,
*ENDSTEP