*HEADING
 RING BUCKLE EIGENVALUE ESTIMATE ( 10*2 STRI3 )
*PREPRINT, HISTORY=NO
*NODE
*NGEN,NSET=ALL,LINE=C
*TRANSFORM,TYPE=C,NSET=ALL
*ELEMENT,TYPE=STRI3
*ELGEN,ELSET=ELMT
*SHELL SECTION,MATERIAL=A1,ELSET=ELMT
1.,3
*MATERIAL,NAME=A1
*ELASTIC
30.E6,
*NSET,NSET=ONE
*NSET,NSET=TWO
*STEP
*BUCKLE
1,
*DLOAD
ELMT,P,-1.0
*BOUNDARY
ALL,3,5
ONE,2
ONE,6
TWO,2
TWO,6
*BOUNDARY,LOAD CASE=2, OP=NEW
ALL,3,5
ONE,2
ONE,6
TWO,1
*EL PRINT
S,
*MODAL FILE
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP