*HEADING
: REFERENCE SOLUTION USING CPE4 ELEMENTS
*NODE
1,0,0
2,0.5,0
3,1.,0
4,0,0.5
5,0.5,0.5
6,1.,0.5
7,0.,1.
8,0.5,1.
9,1.,1.
*NSET, NSET=NMID
6, 
*ELSET, ELSET=EMID
1,3
*ELEMENT,TYPE=CPS4,ELSET=E1
1,1,2,5,4
2,2,3,6,5
3,4,5,8,7
4,5,6,9,8
*SOLID SECTION, ELSET=E1, MATERIAL=MAT
*MATERIAL, NAME=MAT
*ELASTIC,TYPE=ISO
2.E7,0
*DENSITY
8000., 
*DAMPING,ALPHA=5.36,BETA=7.46E-5
*BOUNDARY
1,1,2
4,1,2
7,1,2
*STEP
*FREQUENCY, eigensolver=lanczos, SIM=NO
5, , 
*NODEPRINT
*ELPRINT
*MODAL FILE
*ELFILE
*NODEFILE
*ENDSTEP
*STEP,PERT
*STEADY STATE DYNAMICS,FREQUENCY SCALE=LINEAR
10,15.,50,1
*DLOAD
2,P2,30000.
4,P2,30000.
*MODAL DAMPING,RAYLEIGH
1,5,5.36,7.46E-5
*SELECT EIGENMODES, GENERATE
1,5,1
*EL PRINT, ELSET=EMID
S, 
*NODE PRINT, NSET=NMID
U, 
*NODE FILE, NSET=NMID
U, 
*EL FILE, ELSET=EMID, POSITION=AVERAGED AT NODES, FREQ=50
S, 
*ENDSTEP