各位大神,我在验证材料力学压杆稳定的临界载荷时,构建了两个模型,如下两个命令流:悬臂梁长度5000mm,一端固支,一端施加载荷。
1. 用梁单元beam188构建,悬臂端施加单位载荷1N
2. 用实体单元solid186构建,悬臂端施加压力1/A MPa,A为梁截面积
按材料力学获取的临界载荷Fcr=550N,对两模型求解后,梁单元模型屈曲特征值结果为550,而实体单元模型屈曲特征值为2150,为什么实体单元模型结果与理论解不一样?
!***************压杆稳定(梁单元)
finish
/clear
/prep7
et,1,beam188
keyopt,1,1,1
/eshape,1
mp,ex,1,2e5
mp,nuxy,1,0.3
mp,dens,1,7850e-9
!****加强筋
SECTYPE,1,BEAM,I
SECOFFSET, USER, ,30
SECDATA,30,30,60,6,6,6
k,1
k,2,5000
k,3,,1
l,1,2
latt,1,,1,,3,,1
esize,20
lmesh,all
/solu
dk,1,all
fk,2,fx,-1
allsel
antype,static
PSTRES,1
solve
finish
/post1
PLNSOL, U,x
/solu
antype,buckling
BUCOPT,LANB,10,0,1e6,RANGE
MXPAND,10
SOLVE
!***************压杆稳定(实体单元)
finish
/clear
/prep7
et,1,solid186
et,2,mesh200
KEYOPT,2,1,7
mp,ex,1,2e5
mp,nuxy,1,0.3
mp,dens,1,7850e-9
k,1,-15,-30
k,2,15,-30
k,3,15,-30+6
k,4,3,-30+6
k,5,3,30-6
k,6,15,30-6
k,7,15,30
k,8,-15,30
k,9,-15,30-6
k,10,-3,30-6
k,11,-3,-30+6
k,12,-15,-30+6
a,1,2,3,4,5,6,7,8,9,10,11,12
VOFFST,1,5000
type,2
esize,3
amesh,1
type,1
mat,1
esize,120
vsweep,all
allsel
asel,s,loc,z,0
da,all,all
allsel
!***按面载荷施加
asel,s,loc,z,5000
asum
*GET,x1,AREA, ,AREA
sfa,all,,pres,1/x1
allsel
/solu
antype,static
PSTRES,1
solve
finish
/post1
PLNSOL, U,z
/solu
antype,buckling
BUCOPT,LANB,10,0,1e6,RANGE
MXPAND,10
SOLVE
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