*HEADING
: ACOUSTIC-STRUCTURAL INTERFACE, 2nd-ORDER  [ASI8]
*NODE,NSET=BASE
1, 
21,10.
41,20.
61,0.,10.
81,20.,10.
101,0.,20.
121,10.,20.
141,20.,20.
*NODE,NSET=FSURF
11,0.,0.,100.
31,10.,0.,100.
51,20.,0.,100.
71,0.,10.,100.
91,20.,10.,100.
111,0.,20.,100.
131,10.,20.,100.
151,20.,20.,100.
*NFILL,NSET=FLUID
BASE,FSURF,10,1
*ELEMENT,TYPE=AC3D20
1,1,41,141,101,3,43,143,103,21,81,121,61,23,83,123,
63,2,42,142,102
*ELGEN,ELSET=FLUID
1,5,2,1
*SOLID SECTION,ELSET=FLUID,MATERIAL=WATER
*ELEMENT,TYPE=ASI8,ELSET=INTER
6,1,41,141,101,21,81,121,61
*INTERFACE,ELSET=INTER
*MATERIAL,NAME=WATER
*ACOUSTIC MEDIUM,BULK MODULUS
2.0E9, 
*DENSITY
1000., 
*BOUNDARY
FSURF,8
*AMPLITUDE,DEFINITION=PERIODIC,NAME=SINE
1,10.,0.
0.,1.
*STEP,INC=200
*DYNAMIC,DIRECT
.02,1.
*BOUNDARY,AMP=SINE,TYPE=ACCELERATION
BASE,3,3,1.
*EL PRINT,FREQ=0
*NODE PRINT,FREQ=10
POR,A
*NODE FILE,FREQ=25
POR,A
*END STEP