有初始弯曲的柱子非线性分析问题

笑盈盈

下面是我的命流 我是做有初始弯曲的柱的非线性分析，问题是好像这个初始弯曲并不能使柱子失稳 柱子好像一直在做强度分析，而没有做稳定分析  希望各位大侠帮忙解决一下先谢了
/clear,nostart
/filename,tort
/title,1
/prep7
et,1,shell181
et,2,mass21
r,1,2.8
r,2           
mp,ex,1,2.06e5
mp,prxy,1,0.3
tb,bkin,1
tbdata,1,235,0,,,,  !Q235

!!!!!jiedian!!!!!
k,1,0,8   !jiedian zuobiao (x,y)
k,2,0,0
k,3,-40,0
k,4,-40,10
k,5,-40,20
k,6,-40,55
k,7,-40,65
k,8,-40,75
k,9,0,75
k,10,0,67
k,11,0,8   !jiedian zuobiao (x,y)
k,12,0,0
k,13,40,0
k,14,40,10
k,15,40,20
k,16,40,55
k,17,40,65
k,18,40,75
k,19,0,75
k,20,0,67



l,1,2
l,2,3
l,3,4
l,5,6
l,7,8
l,8,9
l,9,10
larc,5,4,1,5.0   !yuanhulianjie
larc,6,7,1,5.0
lfillt,1,2,2.5   !daojiao
lfillt,2,3,2.5
lfillt,5,6,2.5
lfillt,6,7,2.5

l,11,12
l,12,13
l,13,14
l,15,16
l,17,18
l,18,19
l,19,20
larc,16,17,1,5.0   !yuanhulianjie
larc,14,15,1,5.0
lfillt,18,19,2.5   !daojiao
lfillt,19,20,2.5
lfillt,15,16,2.5
lfillt,14,15,2.5

k,1000,0,0,0      !lashen
k,1001,0,0,8000    !zhugao
k,1002,0,75/2,0
k,1003,0,75/2,8000



!x=a*z*z+b*z+c
a=-1/1000000
b=1/125
c=0

*DO,i,1,201,1   !画关键点  
z=40*i-40
x=a*z*z+b*z+c
k,i+10000,x,0,z
*ENDDO

*DO,i,1,200,1   !连点成线
l,i+10000,i+10000+1
*ENDDO  
   
*DO,i,2,200,1   !叠加生成整个抛物线
LCOMB,27,i+26,0
*ENDDO

adrag,1,10,2,11,3,8,27
adrag,4,9,5,12,6,13,27
adrag,7,,,,,,27

adrag,14,26,15,25,16,22,27
adrag,17,21,18,23,19,24,27
adrag,20,,,,,,27
adele,14,,,1
adele,26,,,1

!!!!!!!!fendanyuan
type,1
mat,1
real,1
lsel,s,length,,7000,8000,1000,0  !zhugao
lesize,all,50,,,,,,,1
allsel
lsel,s,length,,30,35,5,0
lesize,all,3,,,,,,,1
allsel
lsel,s,length,,5.5,7.5,2,0
lesize,all,,,1,,,,,1
allsel
lsel,s,radius,,2.5,,,0
lesize,all,,,1,,,,,1
allsel
lsel,s,radius,,5,,,0
lesize,all,,,2,,,,,1
mshkey,1
!allsel
!asel,u,area,,14
amesh,all,,

NUMMRG,all,,,,low
NUMCMP,all


katt,1,2,2,0
kmesh,56,57,1
nsel,all
NSEL,S,LOC,Z,0
!NSEL,u,NODE,,NODE(0,37.5,0)
CERIG,NODE(0,37.5,0) ,ALL,ALL

nsel,all
NSEL,S,LOC,Z,8000
!NSEL,U,NODE,,NODE(0,37.5,8000)
CERIG,NODE(0,75/2,8000),ALL,ALL

NUMMRG,all,,,,low
NUMCMP,all

!!!!!!!!!!!!!!!jiazai
/solu
nsel,all
d,NODE(0,75/2,0) ,all,0
d,NODE(0,75/2,8000) ,ux,0
d,NODE(0,75/2,8000) ,uy,0
d,NODE(0,75/2,8000) ,rotx,0
d,NODE(0,75/2,8000) ,roty,0
d,NODE(0,75/2,8000) ,rotz,0

allsel,all,node
f,NODE(0,75/2,8000),fz,-150000

!!!!!!!qiujie
ANTYPE,0                     
ALLSEL
nlgeom,on
!lnsrch,1
neqit,50            
outres,all,all
cnvtol,f,,0.05,2,0.05
arclen,on,5,0.0001        !wending
arctrm,u,150,11684,ux
NSUBST,35
allsel
solve
save