特征值分析

wangxiuli2005

我做的是直立储气罐的结构分析,简化成了加劲圆柱壳结构的特征值屈曲分析,我编的命令流做静力分析没有问题,但是做特征值屈曲时就有问题,出来的模态不对,我发现:模型中有一个警告说,实常数1被单元1和单元2使用,我觉得这个问题不大,还有一个警告就是顶壳的壳面法向无法翻转,但是,不影响解题.我把命令流贴出来,请大家帮我看看,问题出在哪里?我怀疑是约束加的不对,我加的约束是柱壳底部的自由度ux,uy,uz被约束,柱壳顶部的uy,ux被约束.
!(1)进入前处理
/PREP7
/units,si
*AFUN,DEG
D=51.2
D1=8
R=48.9189
*dim,h,array,9
h(1)=18.7,32.7,46.7,60.7,74.7,87.6
h(7)=92.627,98.706,16
l=1.46
L1=8


!定义单元属性

ET,1,beam188
ET,2,SHELL63!shell63不支持大应变，shell181支持，
!定义材料属性

MP,EX,1,2.06E11
MP,NUXY,1,0.3
MP,DENS,1,7850

!定义截面形状

SECTYPE,1,BEAM,I, ,0       !立柱截面工字型
SECOFFSET,user,0,0.5
SECDATA,0.35,0.35,0.5,0.014,0.014,0.009


SECTYPE,2,BEAM,chan, ,0      !柜顶c钢
SECOFFSET,user,0.1,0.3
SECDATA,0.2,0.2,0.3,0.012,0.012,0.012

SECTYPE,3,BEAM,CHAN, ,0        !等效的抗风回廊
SECOFFSET,user,0.2,1
SECDATA,0.4,0.4,1,0.02,0.02,0.012
SECTYPE,6,BEAM,L, ,0       ! 肋截面
SECOFFSET,user,0.0375，0
SECDATA,0.075,0.125,0.007,0.007
SECTYPE,7,BEAM,chan, ,0      !柜顶c钢
SECDATA,0.2,0.2,0.3,0.012,0.012,0.012
!设置常数实
R,1,6e-3      !壁壳的厚度
R,2,4e-3        !顶壳的厚度

!建模

CSYS,1
k,1,d/2,0,0
*get,kp_max,kp,,num,max
*do,i,1,9
k,kp_max+i,d/2,0,i*h(9)/8!建立（d/2，0，0，）到（d/2，0，16）9个关键点
l,kp_max+i,kp_max+i-1
*enddo
*do,i,1,6,1
k,kp_max+9+i,d/2,0,h(i)!建立（d/2，0，18.7）到（d/2，0，87.6）6个关键点
l,kp_max+9+i-1,kp_max+9+i
*enddo
!建穹顶关键点
rr=d/2-d1/2
angle=asin(rr/r)
local,11,1,d1/2,0,h(7)-r,90,angle,-90
*get,kp_max,kp,,num,max
csys,11
*do,i,1,6,1
k,kp_max+i,r,i*angle/6,0
*enddo
*get,kp_max,kp,,num,max
k,kp_max+1,r,angle-angle/12,0
csys,1
k,kp_max+2,d1/2,0,h(8)
k,kp_max+3,1,0,h(8)
k,kp_max+4,(d1/2-1)/3+1,0,h(8)
k,kp_max+5,2*(d1/2-1)/3+1,0,h(8)
k,kp_max+6,0,0,0
k,kp_max+7,0,0,1000
!建桁架关键点

!连接穹顶
*get,kp_max,kp,,num,max
csys,11
k,kp_max+1,0,0,0!11号坐标系下的坐标圆点
csys,1
kp_loc=kp(d/2,0,h(6))
csys,11
*do,i,kp_loc,kp_loc+4
larc,i,i+1,kp_max+1,r
*enddo
larc,kp_loc+5,kp_loc+7,kp_max+1,r
larc,kp_loc+7,kp_loc+6,kp_max+1,r
cm,q_ding,line
alls
!连接风帽
csys,1
l,kp(d1/2,0,h(7)),kp(d1/2,0,h(8))
l,kp(d1/2,0,h(8)),kp(2*(d1/2-1)/3+1,0,h(8))
l,kp(2*(d1/2-1)/3+1,0,h(8)),kp((d1/2-1)/3+1,0,h(8))
l,kp((d1/2-1)/3+1,0,h(8)),kp(1,0,h(8))
cm,feng_m,line
alls
!话分分数
lsel,s,loc,z,0,h(9)
lesize,all,,,nint((h(9)/8)/l)
alls
lsel,s,loc,z,h(9),h(1)
lsel,u,loc,z,h(9)
lesize,all,,,nint((h(1)-h(9))/l)
alls
*do,i,2,6
lsel,s,loc,Z,h(i-1),h(i)
lsel,u,loc,Z,h(i)
lesize,all,,,nint((h(i)-h(i-1))/l)
alls
*enddo
lsel,s,loc,z,h(6),h(8)
lsel,u,loc,z,h(8)
lesize,all,,,3
alls
lsel,s,loc,z,h(8)
lesize,all,,,1
alls
lsel,s,loc,z,0,h(8)
lsel,r,loc,y,0
arotat,all,,,,,,kp(0,0,0),kp(0,0,1000),360,24
alls
nummrg,all
numcmp,all
!lsel,s,loc,z,0!设置z=0处的环梁分划分分数
!lesize,all,,,2
!alls
!lsel,s,loc,z,h(9)/2!设置z=h(9)/2处的环梁分划分分数
!lesize,all,,,2
!alls
!lsel,s,loc,z,h(9)!设置z=h(9)处的环梁分划分分数
!lesize,all,,,2
!alls
*do,i,1,6
lsel,s,loc,z,h(i)
lesize,all,,,2
alls
*enddo
lsel,s,loc,z,h(8)!设置z=h(8)处的环梁分划分分数
lesize,all,,,2
alls
*do,i,0,5
g=r*sin(i*angle/6)
lsel,s,loc,x,g+d1/2!灌顶周向环梁的划分分数
lesize,all,,,2
alls
*enddo
g=r*sin(angle/12)
lsel,s,loc,x,g+d1/2
lesize,all,,,2
alls
!****************************************************************给壳体附属性
asel,s,loc,z,0,h(6)
asel,u,loc,z,0
aatt,1,1,2!单元类型是shell63
mshkey,1
mshape,0,2d
amesh,all
asel,s,loc,z,h(6),h(8)
aatt,1,2,2!对灌顶划分网格
mshkey,1
mshape,0,2d
amesh,all
alls
!****************************************************************抗风环梁附属性
*do,i,1,6,1!从h(1)到h(6)的环梁
k,5000+i,0,0,h(i)
lsel,s,loc,z,h(i)
latt,1,,1,,5000+i,,3!没有实常数
lmesh,all
alls
*enddo

!**************************************************************立柱附属性
lsel,s,loc,y,0
*do,i,1,23
lsel,a,loc,y,i*15
*enddo
lsel,r,loc,x,d/2
latt,1,,1,,5001,,1!方向点怎么是5001？
lmesh,all
ALLS
!*************************************************************T围栏附属性
!************************************************************顶壳径向环梁附属性
*do,i,0,23,1
k,11000+i,d1/2,i*15,h(7)-r
*enddo
*do,i,0,23,1
lsel,s,loc,z,h(6),h(7)
*do,j,0,6,1
g=r*sin(j*angle/6)
lsel,u,loc,x,g+d1/2
*enddo
lsel,r,loc,y,i*15
latt,1,,1,,11000+i,,7
lmesh,all
alls
*enddo
!*************************************************************顶壳环向环梁附属性
*dim,fangxiang1,array,9
*do,j,1,5,1
g=r*sin(j*angle/6)
k,12000+j,g+d1/2,0,0
fangxiang1(j)=12000+j
lsel,s,loc,z,h(6),h(7)
lsel,r,loc,x,g+d1/2
latt,1,,1,,fangxiang1(j),,7
lmesh,all
alls
*enddo
alls
k,12006,gg+d1/2,0,0
gg=r*sin(angle/12)
lsel,s,loc,x,gg+d1/2
latt,1,,1,,12006,,7
lmesh,all
alls
!**************************************************************风帽处环梁附属性
lsel,s,loc,z,h(8)!风帽处共有5道环梁
lsel,r,loc,x,1
k,13000,d1/2,0,0
latt,1,,1,,13000,,7
lmesh,all
alls
lsel,s,loc,z,h(8)
lsel,r,loc,x,d1/2
latt,1,,1,,13000,,7
lmesh,all
alls
lsel,s,loc,z,h(7)
lsel,r,loc,x,d1/2
k,13001,d1/2,0,0
latt,1,,1,,13001,,7
lmesh,all
alls
k,13002,(d1/2-1)/3+1,0,h(7)
k,13003,2*(d1/2-1)/3+1,0,h(7)
lsel,s,loc,z,h(8)
lsel,r,loc,x,(d1/2-1)/3+1
latt,1,,1,,13002,,7
lmesh,all
alls
lsel,s,loc,z,h(8)
lsel,r,loc,x,2*(d1/2-1)/3+1
latt,1,,1,,13003,,7
lmesh,all
alls
!************************************************************风帽顶径向梁附属性
*do,j,0,23,1
k,14000+j,d1/2,j*15,h(6)
lsel,s,loc,z,h(8)
lsel,u,loc,x,d/2
lsel,u,loc,x,1
lsel,r,loc,y,j*15
latt,1,,1,,14000+j,,7
lmesh,all
alls
*enddo
!**********************************************************风帽上立柱
k,15000,0,0,h(8)
*do,i,0,23,1
lsel,s,loc,z,h(7),h(8)
lsel,u,loc,z,h(7)
lsel,u,loc,z,h(8)
lsel,r,loc,y,i*15
latt,1,,1,,15000,,7
lmesh,all
alls
*enddo
!*********************************壳面反向
ASEL,S,LOC,Z,h(8)
AREVERSE,ALL,0
ALLSEL,ALL
/solu
lsel,s,loc,z,0
dl,all,,ux
dl,all,,uy
dl,all,,uz
alls
lsel,s,loc,z,h(8)
dl,all,,ux
dl,all,,uy
alls
!*******************************************施加雪荷载
asel,s,loc,z,h(6),h(7)
sfa,all,1,pres,-400
alls
asel,s,loc,z,h(8)
sfa,all,2,pres,400
/solu!求解
antype,static
pstres,on
solve
finish
/solu
antype,buckle
bucopt,lanb,2
save
solve
finish
/solu
expass,on
mxpand,2
finish
/post1
set,first
pldisp,1
finish