含接触的屈曲分析（限制失稳）

tongchanghe

本人在做一个限制失稳的例子：两个圆筒套在一起，外筒为刚性，内筒为柔性，对内筒加压至失稳，内筒变形的过程中与外筒产生接触，由于外筒为刚性，限制了内筒的自由失稳。普通的特征值屈曲分析不包括非线性，所以不知道如何将接触考虑进去。本人在这里采用生死单元的做法：在做特征值屈曲时将接触单元杀死，然后复活接触单元继续做非线性屈曲分析，但是得出的结果不正确，命令流如下，请赐教！
finish
/clear
/TITLE,confined buckling analysis of short cylinder
/PREP7
L=504
L1=514
R=92
R1=92.005
TT=1
N1=30
N2=30
N3=6
ET,1,SHELL181
R,1,TT
MP,EX,1,0.374e5
MP,PRXY,1,0.22
/VIEW,1,1,1,1
CYL4,,,R
VOFFST,1,L
VDELE,1
ADELE,1,2,,1
LSEL,U,LENGTH,,L
LESIZE,ALL,,,N1,,,,,1
ALLSEL
LSEL,,,,9,12,1
LESIZE,ALL,,,N2,,,,,1
ALLSEL
MSHAPE,0,2D
MSHKEY,0
AMESH,ALL
NSEL,S,LOC,Z,L/2
D,ALL,,,,,,UZ
ALLSEL
LSEL,S,,,1,8,1
NSLL,S,1
NPLOT
CSYS,1
NROTAT,ALL
D,ALL,,,,,,UY
ALLSEL
/REPLO
WPOFFS,,,-5
CYL4,,,R1
VOFFST,1,L1
VDELE,1
ADELE,1,2,,1
ALLSEL
!设置接触对
/COM, CONTACT PAIR CREATION - START
MP,MU,1,
MAT,1   
R,3
REAL,3
ET,2,170
ET,3,174
R,3,,,0.1,0.1,0
! Generate the target surface   
ASEL,S,,,7  
ASEL,A,,,8  
ASEL,A,,,9  
ASEL,A,,,10
CM,_TARGET,AREA
AATT,-1,3,2,-1  
TYPE,2  
AMESH,ALL   
! Generate the contact surface  
ASEL,S,,,3  
ASEL,A,,,4  
ASEL,A,,,5  
ASEL,A,,,6  
CM,_CONTACT,AREA
TYPE,3  
NSLA,S,1
ESLN,S,0
ESURF
! Reverse target normals
ASEL, , , ,_TARGET
NSLA,S,1
ESLN,S,1
ESURF,,REVERSE  
/REPLOT
/COM, CONTACT PAIR CREATION - END
ALLSEL  
!特征值屈曲分析
/SOLU
ANTYPE,0
PSTRES,1
ESEL,S,ENAME,,170
ESEL,A,ENAME,,174
EKILL,ALL
ESEL,S,LIVE
ASEL,S,,,3,6,1
SFA,ALL,1,PRES,-1
SOLVE
FINISH
/SOLU
ANTYPE,1
BUCOPT,LANB,1
MXPAND,1,0,0,1,0.001
ALLSEL
SOLVE
FINISH
/POST1
SET,LIST
SET,FIRST
PLDISP,0
!非线性屈曲分析
*GET,load,ACTIVE, ,SET,FREQ
/POST1
SET,LAST
UPCOORD,0.1,ON
/SOL
ANTYPE,0
NLGEOM,1
NROPT,FULL
ESEL,S,ENAME,,170
ESEL,A,ENAME,,174
EALIVE,ALL
ESEL,ALL
NSUBST,50,0,0
OUTRES,ALL,ALL
ARCTRM,L
SFA,ALL,1,PRES,-4*load
SOLVE
FINISH