*HEADING
 RING BUCKLING ANALYSIS, C3D20, 4 X 10 MESH                
*NODE
1,99.5,,
801,100.5
 41,70.35712473,70.35712473
841,71.06423151,71.06423151
*NGEN,NSET=INNER,LINE=C
1,41,1
*NGEN,NSET=OUTER,LINE=C
801,841,1
*NFILL,NSET=ALL1
INNER,OUTER,8,100
*NODE
2001,99.5,,1.0
2801,100.5,,1.0
2041,70.35712473,70.35712473  ,1.0
2841,71.06423151,71.06423151,1.0
*NGEN,LINE=C,NSET=INNER2
2001,2041,1,0,0.,0.,1.
*NGEN,NSET=OUTER2,LINE=C
2801,2841,1,0,0.,0.,1.
*NFILL,NSET=ALL2
INNER2,OUTER2,8,100
*NFILL,NSET=ALL
ALL1,ALL2,2,1000
*NSET,NSET=SYM,GENERATE
1,801,100
1001,1801,100
2001,2801,100
*NSET,NSET=VARY
41,841,100
1041,1841,100
2041,2841,100
*ELEMENT,TYPE=C3D20
1, 1,201,205,5, 2001,2201,2205,2005, 101,203,105,3, 2101,2203,2105,
2003, 1001,1201,1205,1005
*ELGEN,ELSET=EALL
1,4,200,1,10,4,100
*ELSET,GENERATE,ELSET=LOAD
4,1004,100
*MATERIAL ,NAME= A1
*ELASTIC
30.0E6,0.0
*SOLID SECTION,MATERIAL=A1,ELSET=EALL
1.0, 
*TRANSFORM, NSET=VARY
1,1,0,-1,1,0.
*BOUNDARY
ALL1,3
SYM,2
VARY,2
*STEP
*BUCKLE
1,
*DLOAD
LOAD,P4,1.0
*BOUNDARY,LOAD CASE=2, OP=NEW
ALL1,3
SYM,2
VARY,1
*NODE PRINT ,SUMMARY=NO
U,RF
*MODAL PRINT
*MODAL FILE
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP