*HEADING
 Tube with nonreflective end-condition and *TIE constraint.
 Part of the air in the tube is modelled with continuum elements
 with air properties.
************************************************
*NODE, Nset=ODB_NSET
1, 
41,.5
101,,0.0125
141,0.5,0.0125
201,,0.025
241,0.5,0.025
*NGEN,NSET=NBACK
1,41
101,141
201,241
*NCOPY,CHANGE NUMBER=600, OLD SET=NBACK, NEW SET=NFRONT,SHIFT
0.0,0.0,0.025

*NSET,NSET=NALL
NBACK,NFRONT
*NSET,NSET=SAMPLE,GEN
1,41
*NSET,NSET=LOAD1
1,201,801,601
*Nset, Nset=struct_sample
1211,1811,1813,1213
************************************************
*NCOPY,OLDSET=NALL,NEWSET=NSOL,CHANGENUMBER=1000,SHIFT
0.0,0.0,0.0
1.0,0.0,0.0,0.0,1.0,0.0
************************************************
** First 10 elements are acoustic
*ELEMENT,TYPE=AC3D6
1,1,601,603,   201,801,803
2,603,3,1,     803,203,201
*ELGEN,ELSET=ACOU
1,5,2,2
2,5,2,2
** Then 5 continuum elements
*ELEMENT,TYPE=C3D8R
1006,1011,1611,1613,1013,  1211,1811,1813,1213,
*ELGEN,ELSET=STRUCT
1006,5,2,1
** Next 20 elements are acoustic
*ELEMENT,TYPE=AC3D6
101,21,621,623,   221,821,823
102,623,23,21,    823,223,221
*ELGEN,ELSET=ACOU
101,10,2,2
102,10,2,2
*ELSET,ELSET=NONREF
120,
************************************************
*SURFACE,TYPE=ELEMENT,NAME=ACR
10,S3
*SURFACE,TYPE=ELEMENT,NAME=SOL
1006,S3
*SURFACE,TYPE=ELEMENT,NAME=SOR
1010,S5
*SURFACE,TYPE=ELEMENT,NAME=ACL
101,S3
*TIE,NAME=CRAVAT
SOL,ACR
ACL,SOR
************************************************
**
**  Acoustic Element Properties
**
*SOLID SECTION,MATERIAL=AIR,ELSET=ACOU
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
************************************************
**
**  Continuum Element Properties
**
*SOLID SECTION,MATERIAL=AIRSOLID,ELSET=STRUCT
*MATERIAL,NAME=AIRSOLID
*DENSITY
 1.21,
*ELASTIC
 0.1424E6,
************************************************
*Elset,Elset=ODB_ESET
ACOU, STRUCT
*Nset, Nset=ODB_NSET
ODB_NSET, NBACK, NFRONT
NALL, SAMPLE, LOAD1
*BOUNDARY
NSOL,2,3
************************************************ 
*STEP
*FREQUENCY
70,
*OUTPUT,FIELD,FREQ=0
*END STEP
**------------------------------------------------
*STEP,inc=10000
*MODAL DYNAMIC
0.00001,.005
*CLOAD
LOAD1, 8,314.1592654
** simulation of uniaxial condition
*OUTPUT,FIELD,FREQ=1000
*ELEMENT OUTPUT,ELSET=STRUCT
S
*NODE OUTPUT,NSET=SAMPLE
POR,
*OUTPUT,HISTORY,FREQUENCY=1
*NODE OUTPUT,NSET=SAMPLE
POR,
*NODE OUTPUT,NSET=struct_sample
u,
*END STEP
**------------------------------------------------
*STEP,inc=10000
*DYNAMIC
0.00001,.005
*CLOAD
LOAD1, 8,314.1592654
** simulation of uniaxial condition
*OUTPUT,FIELD,FREQ=1000
*ELEMENT OUTPUT,ELSET=STRUCT
S
*NODE OUTPUT,NSET=SAMPLE
POR,
*OUTPUT,HISTORY,FREQUENCY=1
*NODE OUTPUT,NSET=SAMPLE
POR,
*NODE OUTPUT,NSET=struct_sample
u,
*END STEP