*parameter
factor=1.e0
acousticbulk=20000.0*factor
acousticdens=1.e-4*factor
*NODE
     53,     27.04292,         -30.
     54,     32.90476,         -30.
     58,     32.90476,         -25.
     59,     27.04292,         -25.
**
     153,     27.04292,         -27.5
     154,     32.90476,         -27.5
**
     43,          27.04292,         -20.
     44,          27.04292,         -25.
     254,         32.90476,         -20.
     55,          32.90476,         -25.
*Element, type=AC2D4,elset=air
40,  43,  44,  55,  254
*Element, type=CPE4,elset=solid
27,  59,  153,  154,  58
127,153,  53,   54,   154
**27,  59,  53,  54,  58
*Solid Section, elset=air, material=air
1.,
*Solid Section, elset=solid, material=solid
1.,
*Material, name=air
*Acoustic Medium
<acousticbulk>,
*Density
<acousticdens>,
*Material, name=solid
*Density
1.e-1
*Elastic
1000.,0.
***************
*surface,name=air
air,s2
*surface,name=solid
27,s4
*tie,name=airsol,adjust=yes
air,solid
*****************
*nset,nset=retained,unsorted
53,54
*nset,nset=n58
58,
*nset,nset=n154
154,
*nset, nset=n44
44,
*nset,nset=nout
58,59,43,254
*boundary
53,1,2
54,1,2
********************************************
*step
*frequency,norm=mass, SIM
12,,,-1
*output,field
*node output
u,por
*end step
******************
*step
*substructure generate,type=z1,overwrite,libr=substr_small_ac2d4,
recovery matrix=yes, mass matrix=yes
*boundary,op=new
*substructure load case,name=load58
*cload
58,2,1.058
*substructure load case,name=load154
*cload
154,1,10.54
*retained nodal dofs,sorted=no
retained,
**
**
*SELECT EIGENMODES,generate
1,12,1
**
**
** *substructure matrix output, stiffness=yes,file=substr_small_ac2d4,
** mass=yes, recovery=yes,sload=yes
*end step
******************************************