*HEADING
**
*PREPRINT, ECHO=YES, MODEL=YES, HISTORY=YES
*NODE,NSET=BEAMS,SYSTEM=C
********************************
*NODE,NSET=STIFFNER
*****
*NGEN,NSET=BEAMS,LINE=C
*NSET,NSET=OUT
*ELEMENT,TYPE=B21,ELSET=BEAMS
*ELGEN,ELSET=BEAMS
*ELEMENT,TYPE=B21,ELSET=STIFFNER
******************
*INCLUDE,INPUT=acoustic_ellipse_stdelem.inp
*INCLUDE,INPUT=acoustic_ellipse_node.inp
*NSET, NSET=INNER, GENERATE
*NSET, NSET=OUTER, GENERATE
*ELSET, ELSET=OUTER,  GENERATE
*ELSET, ELSET=INNER, GENERATE
*SURFACE, TYPE=ELEMENT, NAME=SLAVE
INNER, S1
*ELSET, ELSET=_SURF-2_S3, GENERATE
*SURFACE, TYPE=ELEMENT, NAME=OUTER
_SURF-2_S3, S3
*SURFACE,TYPE=ELEMENT,NAME=MASTER
BEAMS,SPOS
*TIE,NAME=COUPLING
SLAVE,MASTER
************************************
*MATERIAL,NAME=WATER
*DENSITY
1000.0,
*ACOUSTIC MEDIUM,BULK MODULUS
*ACOUSTIC MEDIUM,VOLUMETRICDRAG
*IMPEDANCE PROPERTY,NAME=BGT_AUTO,TYPE=E
*SOLID SECTION,MATERIAL=WATER,ELSET=ACOUSTIC
0.1
*******************
*BEAM SECTION,MATERIAL=MAT1,ELSET=BEAMS,SECTION=RECT
0.1,0.1
*BEAM SECTION,MATERIAL=MAT1,ELSET=STIFFNER,SECTION=RECT
0.1,0.1
*MATERIAL,NAME=MAT1
*ELASTIC
207E9,0.3
*DENSITY
7800
*************************
*AMPLITUDE,DEFINITION=PERIODIC,NAME=SINE
1,628.3185,0,0.0
0.0,1.0
**********************
*STEP,inc=1000,nlgeom=yes
*DYNAMIC,alpha=0.0
2.5e-5,0.003
*IMPEDANCE
OUTER,I3,BGT_AUTO
*BOUNDARY,AMP=SINE,TYPE=ACCEL
2075,2,2,1.0E4
*BOUNDARY
25001,1,1,0.0
25071,1,1,0.0
25001,6,6,0.0
25071,6,6,0.0
2055,1,1,0.0
2055,6,6,0.0
*OUTPUT,FIELD,freq=50
*NODE OUTPUT
POR
*OUTPUT,HISTORY,freq=50
*node output,nset=inner
por
*END STEP
*STEP,inc=1000,nlgeom=yes
*DYNAMIC,alpha=0.0
2.5e-5,0.003
*IMPEDANCE,OP=NEW
*SIMPEDANCE,OP=NEW
OUTER,BGT_AUTO
*BOUNDARY,AMP=SINE,TYPE=ACCEL
2075,2,2,1.0E4
*BOUNDARY
25001,1,1,0.0
25071,1,1,0.0
25001,6,6,0.0
25071,6,6,0.0
2055,1,1,0.0
2055,6,6,0.0
*OUTPUT,FIELD,freq=50
*NODE OUTPUT
POR
*OUTPUT,HISTORY,freq=50
*node output,nset=inner
por
*END STEP
************************