*Heading
** 
*PREPRINT, ECHO=NO, MODEL=NO, HISTORY=NO
*NODE,NSET=BEAMS,SYSTEM=C
      25001,4.0,90.0,0.0
      25071,4.0,-90.0,0.0
********************************
*NODE,NSET=STIFFNER
26055,0.0,-2.0
26065,1.0,-2.0
26075,3.0,-1.1
*****
*NGEN,NSET=BEAMS,LINE=C
 25001,25071,1,,0,0,0,0,0,-1
*NSET,NSET=OUT
 25001, 25071, 25036,26075
*ELEMENT,TYPE=SAX1,ELSET=BEAMS
12001, 25001,25002
*ELGEN,ELSET=BEAMS
12001,70,1,1
*ELEMENT,TYPE=SAX1,ELSET=STIFFNER
13001,26055,26065
14001,26065,25060
15001,26075,25048
16001,26075,25040
*SURFACE,TYPE=ELEMENT,NAME=MASTER
BEAMS,SPOS
***********************************
*INCLUDE,INPUT=acoustic_3dref_elem.inp
*INCLUDE,INPUT=acoustic_2dref_node.inp
*NSET, NSET=INNER
  1,  41,   1
*ELSET, ELSET=INNER
  1,  40,   1
*NSET, NSET=OUTER
 3240,  3280,     1
*ELSET, ELSET=OUTER
 3121,  3160,     1
*ELSET, ELSET=_INNER_S1, GENERATE
  1,  40,   1
*SURFACE, TYPE=ELEMENT, NAME=SLAVE
_INNER_S1, S1
*ELSET, ELSET=_OUTER_S3, GENERATE
 3121,  3160,     1
*SURFACE, TYPE=ELEMENT, NAME=OUTER
_OUTER_S3, S3
*TIE,NAME=COUPLING
slave,master
************************************
*MATERIAL,NAME=WATER
*DENSITY
1000.0, 
*ACOUSTIC MEDIUM,BULK MODULUS
2.25E9,
*SOLID SECTION,MATERIAL=WATER,ELSET=ACOUSTIC
0.1,
*******************
*SHELL SECTION,MATERIAL=MAT1,ELSET=BEAMS
0.1
*SHELL SECTION,MATERIAL=MAT1,ELSET=STIFFNER
0.1
*MATERIAL,NAME=MAT1
*ELASTIC
207E9,0.3
*DENSITY
7800
*STEP,INC=1200
*STEADY STATE DYNAMIC,DIRECT
1.0,40.0,2,1
*IMPEDANCE,NONREFLECTING=SPHER
OUTER,I3,28.0
*CLOAD
26055,2,100.0
*BOUNDARY
25001,1,1,0.0
25071,1,1,0.0
25001,6,6,0.0
25071,6,6,0.0
26055,1,1,0.0
26055,6,6,0.0
*OUTPUT,FIELD,FREQ=1
*NODE OUTPUT,NSET=BEAMS
U
*NODE OUTPUT
POR
*OUTPUT,HISTORY,freq=50
*NODE OUTPUT,NSET=out
POR
*NODE OUTPUT,NSET=inner
POR
*END STEP
************************
*STEP,INC=1200
*STEADY STATE DYNAMIC,DIRECT
1.0,40.0,2,1
*IMPEDANCE,OP=NEW,NON=SPHER
*SIMPEDANCE,NONREFLECTING=SPHER
OUTER,28.0
*CLOAD
26055,2,100.0
*BOUNDARY
25001,1,1,0.0
25071,1,1,0.0
25001,6,6,0.0
25071,6,6,0.0
26055,1,1,0.0
26055,6,6,0.0
*OUTPUT,FIELD,FREQ=1
*NODE OUTPUT,NSET=BEAMS
U
*NODE OUTPUT
POR
*OUTPUT,HISTORY,freq=50
*NODE OUTPUT,NSET=out
POR
*NODE OUTPUT,NSET=inner
POR
*END STEP