*HEADING
 SQUARE PLATE - ELASTIC BUCKLING  ( BUCKLE )- STRI3 4 x 4    
*NODE
101,
105,1.,
501,0.,1.
505,1.,1.
*NGEN,NSET=YSYM
101,105
*NGEN,NSET=XSYM
101,501,100
*NGEN,NSET=YEDG
501,505
*NGEN,NSET=XEDG
105,505,100
*NFILL
XSYM,XEDG,4,1
*ELEMENT,TYPE=STRI3,ELSET=ONE
1,101,102,202
17,101,202,201
*ELGEN,ELSET=ONE
1,4,1,1,4,100,4
17,4,1,1,4,100,4
*SHELL SECTION,MATERIAL=A1,ELSET=ONE
0.01,3
*MATERIAL,NAME=A1
*ELASTIC
1.E8,0.3
*BOUNDARY
YSYM,YSYMM
XSYM,XSYMM
YEDG,3
YEDG,5
XEDG,3
XEDG,4
XEDG,6
*STEP
*BUCKLE
3,
*CLOAD
105,1,-12.5
205,1,-25.0
305,1,-25.0
405,1,-25.0
505,1,-12.5
*NODE PRINT
U,
*MODAL FILE
*END STEP