*HEADING
: EIGENVALUE ANALYSIS OF AN UNCONSTRAINED PATCH OF ELEMENTS  [CPEG4I]
*PREPRINT,ECHO=YES,HISTORY=NO,MODEL=NO
*NODE
1000,0,0,0
10,0,0
20,.24,0.
30,.24,.12
40,0.,.12
50,.12,0.
60,.24,.06
70,.12,.12
80,.0,.06
102,.04,.02
104,.18,.03
204,.16,.08
202,.08,.08
*NGEN
102,104
202,204
102,202,50
104,204,50
10,102,46
40,202,81
30,204,87
20,104,42
*ELEMENT,TYPE=CPEG4I,ELSET=EALL
1, 10, 20,104,102
2, 10,102,202, 40
3,102,104,204,202
4,104, 20, 30,204
5,202,204, 30, 40
*SOLID SECTION,MATERIAL=A1,ELSET=EALL,REFNODE=1000
.001, 
*MATERIAL,NAME=A1
*ELASTIC,TYPE=ISOTROPIC
1.E6,.25
*DENSITY
7.5E-4, 
*NSET,NSET=SIDES,GENERATE
10,80,10
*STEP
*FREQUENCY, eigensolver=lanczos, SIM=NO
7, , ,-1.E7 
*MODAL FILE
**
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
**
*CONTROLS,PARAMETERS=FIELD
1.E-14, 1., , , 1.E-12
**
*END STEP
*STEP,NLGEOM
*STATIC
*DLOAD
1, P1, -10000.
2, P4, -10000.
4, P2, -10000.
5, P3, -10000.
*BOUNDARY
10,1,2
20,2
*EL PRINT,FREQ=0
*NODE PRINT
U, 
RF, 
*END STEP
*STEP,NLGEOM
*FREQUENCY, eigensolver=lanczos, SIM=NO
7, , , -1.E7 
*MODAL FILE
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*EL PRINT,FREQ=0
*NODE PRINT,FREQ=0
*BOUNDARY,OP=NEW
*END STEP