*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 5 elements are acoustic
*ELEMENT,TYPE=AC3D5
  1,1,201,801,601,3
101,601,801,803,603,3
201,201,203,803,801,3
  2,5,605,805,205,3
102,603,803,805,605,3
202,203,205,805,803,3
*ELGEN,ELSET=ACOU
  1,3,4,2
101,3,4,2
201,3,4,2
  2,2,4,2
102,2,4,2
202,2,4,2
** Then 5 continuum elements
*ELEMENT,TYPE=C3D8R
6,1011,1611,1613,1013,  1211,1811,1813,1213,
*ELGEN,ELSET=STRUCT
6,5,2,1
** Next 10 elements are acoustic
*ELEMENT,TYPE=AC3D5
 11,21,221,821,621,23
111,623,621,821,823,23
211,823,821,221,223,23
 12,25,625,825,225,23
112,623,823,825,625,23
212,823,223,225,825,23
*ELGEN,ELSET=ACOU
 11,5,4,2
111,5,4,2
211,5,4,2
 12,5,4,2
112,5,4,2
212,5,4,2
*ELSET,ELSET=NONREF
20,
************************************************
*SURFACE,TYPE=ELEMENT,NAME=ACR
105,S4
205,S3
*SURFACE,TYPE=ELEMENT,NAME=SOL
6,S3
*SURFACE,TYPE=ELEMENT,NAME=SOR
10,S5
*SURFACE,TYPE=ELEMENT,NAME=ACL
11,S1
*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, SIM=NO
70,,,-1000
*OUTPUT,FIELD,FREQ=0
*END STEP
**------------------------------------------------
*STEP,inc=10000
*MODAL DYNAMIC
0.00001,.005
*CLOAD
LOAD1, 8, 1.5625
** 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, 1.5625
** 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