*HEADING
 : NAFEMS BENCHMARK EXAMPLE 3DNLG-6
 BUCKLING OF A FLAT PLATE WHEN SUBJECTED TO IN-PLANE SHEAR
*RESTART,WRITE,FREQ=999
*NODE
*ELEMENT, TYPE=S8R5, ELSET=PID1
*SHELL SECTION, ELSET=PID1, MATERIAL=MID1
        12.5,   5
*MATERIAL, NAME=MID1
*ELASTIC, TYPE=ISO
      6.4E+6,     0.3
*NSET,NSET=NODECENTER
*NSET,NSET=EDGE
*ELSET, ELSET=ESIDE1, GENERATE
*ELSET, ELSET=ESIDE2, GENERATE
*ELSET, ELSET=ESIDE3, GENERATE
*ELSET, ELSET=ESIDE4, GENERATE
*SURFACE, NAME=EDGE1
 ESIDE1,E1
*SURFACE, NAME=EDGE2
 ESIDE2,E2
*SURFACE, NAME=EDGE3
 ESIDE3,E3
*SURFACE, NAME=EDGE4
 ESIDE4,E4
*STEP, INC=1000, NLGEOM
*STATIC,RIKS
         0.01,      1.,   1.E-5,      0.01, 1
*BOUNDARY, OP=NEW
 EDGE, 3,3, 0.
 NODECENTER, 1,2, 0.
 NODECENTER, 6,6, 0.
*DSLOAD, FOLLOWER=NO, CONSTANT RESULTANT=YES
 EDGE1,EDLD,2.12E5,-1., 0., 0.
 EDGE2,EDLD,2.12E5, 0., 1., 0.
 EDGE3,EDLD,2.12E5, 1., 0., 0.
 EDGE4,EDLD,2.12E5, 0.,-1., 0.
*OUTPUT,FIELD,FREQ=999
*NODE OUTPUT
 U,
*OUTPUT,HISTORY,FREQ=1
*NODE OUTPUT,NSET=NODECENTER
 U,
*NODE PRINT,FREQ=999,NSET=NODECENTER
 U3,
*NODE FILE, FREQ=1,NSET=NODECENTER
 U,
*EL PRINT,FREQ=0
*END STEP