*HEADING
 RING BUCKLE EIGENVALUE ESTIMATE ( 1 S8R5 )   
*NODE,NSET=Y0
101,100.,0.,1.
201,100.,0.,.5
301,100.,0.,0.
*NODE,NSET=END
103,70.71067812,70.71067812,1.
203,70.71067812,70.71067812,.5
303,70.71067812,70.71067812,0.
*NGEN,LINE=C,NSET=TOP
101,103,1,0,0.,0.,1.
*NGEN,LINE=C,NSET=BOT
301,303,1,0,0.,0.,0.
*ELEMENT,TYPE=S8R5,ELSET=RING
1,101,301,303,103,201,302,203,102
*SHELL SECTION,MATERIAL=A1,ELSET=RING
1.,3
*MATERIAL,NAME=A1
*ELASTIC
30.E6,0.
*TRANSFORM,NSET=END
1.,1.,0.,-1.,1.,0.
*STEP
*BUCKLE
1,
*DLOAD
RING,P,-1.
*BOUNDARY
TOP,3,5
BOT,3,5
Y0,YSYMM
END,YSYMM
*BOUNDARY,LOAD CASE=2, OP=NEW
TOP,3,5
BOT,3,5
Y0,YSYMM
END,1
END,3
END,5
*MODAL FILE
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP