压杆稳定性分析

suck110

再求解屈曲分析时，出现了Block Lanczos solver failure.  The assembled stress stiffness matrix contains all zeroes.  No load factor solution is possible. 的错误。
命令流如下，
/PREP7  
ET,1,BEAM188
KEYOPT,1,1,1
MPTEMP,,,,,,,,  
MPTEMP,1,0  
MPDATA,EX,1,,2.1e11
MPDATA,PRXY,1,,0.3  
SECTYPE,   1, BEAM, CSOLID, , 0
SECOFFSET, CENT
SECDATA,50,0,0,0,0,0,0,0,0,0,0,0
K, ,0,0,0,  
K, ,5000,0,0,   
K, ,15000,0,0,  
LSTR,       1,       2  
LSTR,       2,       3  
TYPE,   1   
MAT,       1
REAL,   
ESYS,       0   
SECNUM,   1
!*  
FLST,5,2,4,ORDE,2   
FITEM,5,1   
FITEM,5,-2  
CM,_Y,LINE  
LSEL, , , ,P51X
CM,_Y1,LINE
CMSEL,,_Y   
!*  
LESIZE,_Y1,100, , , , , , ,1
!*  
FLST,2,2,4,ORDE,2   
FITEM,2,1   
FITEM,2,-2  
LMESH,P51X  
FINISH  
/SOL
!*  
ANTYPE,0
PSTRES,1
FLST,2,1,3,ORDE,1   
FITEM,2,1   
!*  
/GO
DK,P51X, , , ,0,ALL, , , , , ,  
FLST,2,2,3,ORDE,2   
FITEM,2,2   
FITEM,2,-3  
!*  
/GO
DK,P51X, , , ,0,UX,UY,UZ, , , ,
FLST,2,1,3,ORDE,1   
FITEM,2,1   
!*  
/GO
FK,P51X,FX,7860
FLST,2,1,3,ORDE,1   
FITEM,2,3   
!*  
/GO
FK,P51X,FX,-7860
/STATUS,SOLU
SOLVE   
FINISH  
/SOL
ANTYPE,1
!*  
!*  
BUCOPT,LANB,1,0,0,CENTER
MXPAND,1,0,0,0,0.001,   
/STATUS,SOLU
SOLVE
求大神解惑

suck110

约束施加有问题，改成
FLST,2,1,3,ORDE,1   
FITEM,2,1   
!*  
/GO
DK,P51X, , , ,0,UX,UY,UZ,ROTY, , ,  
FLST,2,2,3,ORDE,2   
FITEM,2,2   
FITEM,2,-3  
!*  
/GO
DK,P51X, , , ,0,UY,UZ,ROTY, , , ,  
后，提示Repeated Lanczos shift and factorize steps did not yield additional buckling modes in the requested eigenvalue range.  Either the modes are widely separated or, there are only 0 modes in the neighborhood specified by SHIFT value in BUCOPT command.