*HEADING
: EIGENVALUE ANALYSIS OF AN UNCONSTRAINED PATCH OF ELEMENTS  [STRI3]
*PREPRINT,ECHO=YES,HISTORY=NO,MODEL=NO
*NODE,NSET=ALL
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,NSET=ALL
102,104
202,204
102,202,50
104,204,50
10,102,46
40,202,81
30,204,87
20,104,42
*ELEMENT,TYPE=STRI3, ELSET=EALL
1,10,104,102
2,10,20,104
3,10,102,40
4,102,104,204
5,104,20,204
6,20,30,204
7,102,202,40
8,102,204,202
9,202,30,40
10,202,204,30
*SHELL SECTION,MATERIAL=A1, ELSET=EALL
.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
10, , ,-1.E7
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP