关于BEAM188单元使用问题

zzs8886

今天用beam188单元算静力分析，发现一个错误Shear modulus must be positive for material 1 in element 1  不知道怎么纠正啊！
material1是正交各向异性的复合材料  E11=68900MPA  E22=22700MPA  μ=0.751
在section里定义了梁的截面形状 为半径分别为2,3的空心圆管 不管算什么都会出现那个错误，应该是参数设置问题吧，是不是beam188不能使用正交各向异性的材料啊，换成beam4定义相似的实常数后问题就没有了，可beam4不能模拟截面形状啊，想用beam188，请问如何解决

zzs8886

咋一个回复也没有啊  都回家度假了吗

xtddpla

这个单元比较特殊的

277136394

首先要明确你输入的材料属性有没有问题，是否漏了泊松比？
若BEAM 188不行，可以考虑用BEAM 44单元，它也可以定义截面。
若可以，把你的命令流发上来，让大家讨论下。

zzs8886

回复 4# 277136394
我试了一下直接给一个beam188梁单元加载，还是输入上面提到的参数，出现了同样的错误，不知道究竟是为什么

liudapengsnd

/PREP7
/TITLE, BUCKLING OF A BAR WITH HINGED SOLVES
ET,1,BEAM3                ! Beam element
R,1,.25,52083E-7,.5       ! Area,IZZ, height
MP,EX,1,30E6              ! Define material properties
N,1
N,11,,100
FILL
E,1,2
EGEN,10,1,1
FINISH

/SOLU
ANTYPE,STATIC             ! Static analysis
PSTRES,ON                 ! Calculate prestress effects
D,1,ALL                   ! Fix symmetry ends
F,11,FY,-1                ! Unit load at free end
SOLVE
FINISH

/SOLU
ANTYPE,BUCKLE             ! Buckling analysis
BUCOPT,LANB,1             ! Use Block Lanczos solution method, extract 1 mode
MXPAND,1                  ! Expand 1 mode shape
SOLVE
FINISH
/POST1
SET,FIRST
PLDISP,1
FINISH

liudapengsnd

/GRAPHICS,POWER
/GST,ON
/SHOW,BUCKLE,GRPH
/PREP7
K,1,0,0,0
K,2,100.0,0,0
K,3,50,5,0
LSTR,1,2
ET,1,BEAM189
SECTYPE,1, BEAM, RECT
SECDATA, 0.2, 5.0
SLIST, 1, 1
MP,EX,1,1E4
MP,NUXY,1,0.0
LSEL,S, , , 1, 1, 1
LATT,1, ,1,0, 3, ,1
LESIZE, all, , ,10
SECNUM,1
LMESH,all
/VIEW,,1,1,1
/ESHAPE,1
EPLOT
DK,1, , , ,0,ALL
FK,2,FY,1.0
FINISH
/SOLU
PSTRES,ON
EQSLV,SPARSE          ! EQSLV,SPARSE is the default for static and full transient
SOLVE
FINISH
/SOLU
ANTYPE,BUCKLE
BUCOPT,LANB,4
MXPAND,4,,,YES
SOLVE
FINISH
/POST1
/ESHAPE,1
/VIEW, 1 ,1,1,1
/ANG, 1
SET,LIST
SET,1,1
PLDISP,2
FINISH
/PREP7
UPGEOM,0.002,1,1,file,rst
/SOLU
ANTYPE,STATIC
OUTRES,ALL,ALL
NLGEOM,ON
ARCLEN,ON,25,0.0001
ARCTRM,U,1.0,2,UZ
NSUBST,10000
SOLVE
FINISH
/POST26
NSOL,2,2,U,Z,TIPLATDI
RFORCE,3,1,F,Y
PROD,4,3, , , , , ,-1.0,1,1
XVAR,2
PLVAR,4
PRVAR,2,4
FINISH

liudapengsnd

/GRAPHICS,POWER
/GST,ON
/SHOW,BUCKLE,GRPH
/PREP7
K,1,0,0,0
K,2,100.0,0,0
K,3,50,5,0
LSTR,1,2
ET,1,BEAM189
SECTYPE,1, BEAM, RECT
SECDATA, 0.2, 5.0
SLIST, 1, 1
MP,EX,1,1E4
MP,NUXY,1,0.0
LSEL,S, , , 1, 1, 1
LATT,1, ,1,0, 3, ,1
LESIZE, all, , ,10
SECNUM,1
LMESH,all
/VIEW,,1,1,1
/ESHAPE,1
EPLOT
DK,1, , , ,0,ALL
FK,2,FY,1.0
FINISH
/SOLU
PSTRES,ON
EQSLV,SPARSE          ! EQSLV,SPARSE is the default for static and full transient
SOLVE
FINISH
/SOLU
ANTYPE,BUCKLE
BUCOPT,LANB,4
MXPAND,4,,,YES
SOLVE
FINISH
/POST1
/ESHAPE,1
/VIEW, 1 ,1,1,1
/ANG, 1
SET,LIST
SET,1,1
PLDISP,2
FINISH
/PREP7
UPGEOM,0.002,1,1,file,rst
/SOLU
ANTYPE,STATIC
OUTRES,ALL,ALL
NLGEOM,ON
ARCLEN,ON,25,0.0001
ARCTRM,U,1.0,2,UZ
NSUBST,10000
SOLVE
FINISH
/POST26
NSOL,2,2,U,Z,TIPLATDI
RFORCE,3,1,F,Y
PROD,4,3, , , , , ,-1.0,1,1
XVAR,2
PLVAR,4
PRVAR,2,4
FINISH

zzs8886

回复 8# liudapengsnd
能说一下重要精神吗