我的ansys命令流为啥得不到正确结果?

目的是在薄壁杆件的面上加beam元素,提高局部屈曲能力,得到近似于纯全局屈曲的解.(正确解应该在3300左右)

*afun,deg
B0=33
H0=20
T=0.405
B=B0-T
H=H0-T
L=425
NG=4
NS=6
NL=50

/prep7
ET,1,SHELL63
ET,2,BEAM4
R,1,t
R,2,0.000001,1000,1000,1,1,0,
RMORE,0,0.000001
R,3,1e-006,100000,100000,1,1,0,
RMORE,0,100,0,0,0,0,
MP,EX,1,21000
MP,PRXY,1,0.3

K,1,0,-H/2,0
K,2,0,-H/2,B/2
K,3,0,H/2,0
K,4,0,H/2,B/2


L,1,2,NG
k,5,L/2,-H/2,0
LATT,1,2,2,,5
LMESH,1




L,3,4,NG
k,5,L/2,H/2,0
LATT,1,2,2,,5
LMESH,2

L,2,4,NS
k,5,L/2,-H/2,0
LATT,1,2,2,,5
LMESH,3


K,5,L/2,H/2,B/2
L,4,5,NL
ADRAG,1,2,3,,,,4
*do,i,1,(nl-1),1
LSEL,NONE
K,9+i*4-3,i*(L/2)/nl,H/2,0
K,9+i*4-2,i*(L/2)/nl,H/2,B/2
K,9+i*4-1,i*(L/2)/nl,-H/2,B/2
K,9+i*4,i*(L/2)/nl,-H/2,0
L,9+i*4-3,9+i*4-2
L,9+i*4-2,9+i*4-1
L,9+i*4-1,9+i*4


LATT,1,3,2

Lmesh,all
allsel,all
*Enddo
LSEL,ALL
NUMMRG, NODE, , , ,LOW
ASEL,S,LOC,Y,-H/2
CM,Obergurt,area

ASEL,S,LOC,Y,H/2
CM,Untergurt,area

ASEL,S,LOC,Z,B/2
CM,Steg,area

AATT,1,1,1
ALLSEL
AMESH,ALL




/SOLU
ANTYPE,STATIC
PSTRESS,ON
LSEL,S,LOC,X,L/2
DL,ALL,,SYMM
ALLSEL

LSEL,S,LOC,Z,0
DL,ALL,,SYMM
ALLSEL



D,NODE(0,0,B/2),UY
FLAECHE=(B+H)*2*T !Querschnittsflaeche
PL=1/FLAECHE*T
LSEL,S,LOC,X,0
SFL,All,PRES,PL,PL
ALLSEL


SOLVE
FINISH

/SOLU
ANTYPE,BUCKLE
BUCOPT,SUBSP,50,0
solve

/POST1
SET,FIRST
SET,LIST
PLDISP,1
FINISH





save