*HEADING
 STL Case 1: mass and AC3D8 ELEMENTS. Analytical Solution:
Mass displacement: (Re + i*Im) = -i/(i*Omega*M/A + rho_F c_0)
Transmitted Pressure: (Re + i*Im) = i*Omega*rho_F*c_0*{mass displ.}
** where Omega = angular frequency
**           M = mass of solid
**           A = area of solid
**       rho_F = fluid density
**         c_0 = fluid speed of sound
**
*preprint,model=y,hist=y,contact=yes
************************************************
*Node,nset=mass
10003,0,0,0
*node
10004,0.00000e+000,  2.50000e-003,  0.00000e+000
10005,0.00000e+000,  2.50000e-003,  2.50000e-002
10006,0.00000e+000,  0.00000e+000,  2.50000e-002
*NODE,NSET=SOURCE
10001,-50,0,0
**10001,0,.50,0
**10001,0,-.50,0
*NODE,NSET=STANDOFF
10002,0,0,0
**10002,.50,0.0,0
*NODE, Nset=ODB_NSET
1, 
41,.5
101,,0.0125
141,0.5,0.0125
201,,0.0025
241,0.5,0.0025
*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=BC,gen
201,241
801,841
************************************************
*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
************************************************
*element,type=m3d4,elset=mass
10001,   10003,10004,10005,10006
*ELEMENT,TYPE=AC3D8
1,1,601,603,3,   201,801,803,203
*ELGEN,ELSET=ACOU
1,20,2,1
*ELSET,ELSET=NONREF
20,
************************************************
*SURFACE,NAME=LOADACO
1,S3
*SURFACE,NAME=PWA
20,S5
*SOLID SECTION,MATERIAL=AIR,ELSET=ACOU
*membrane section,material=mass,elset=mass
0.01,
*surface,name=mass
mass,spos
*tie,name=cravatte
loadaco,mass
*surface,name=loadmass
mass,sneg
************************************************
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
*MATERIAL,NAME=MASS
*ELASTIC
210E9,0.3
*DENSITY
7800,
************************************************
*AMPLITUDE,NAME=OMEGA
0.,0., 1E6,6.2831853E6
************************************************
*INCIDENT WAVE INTERACTION PROP,NAME=IWIPROPY,ty=pl
343.05,1.21
************************************************  
*Elset,Elset=ODB_ESET
ACOU,
*Nset, Nset=ODB_NSET
ODB_NSET, NBACK, NFRONT
NALL, SAMPLE, LOAD1
************************************************  
*STEP
*STEADY STATE DYNAMIC,DIRECT,fre=lin
6.461,129.22,20
**
*incident wave interaction,load case,prop=iwipropy,press=Omega
loadmass,source,standoff,1.0
** simulation of uniaxial condition
*SIMPEDANCE,NON=PL
PWA,
*OUTPUT,FIELD,FREQUENCY=1
*NODE OUTPUT
POR,u
*OUTPUT,HISTO,FREQUENCY=1
*NODE OUTPUT,nset=mass
u1,
*NODE OUTPUT,nset=load1
POR,
*END STEP