求助：悬臂梁模态分析无扭转振型？
本帖最后由 mp2625 于 2010-11-6 09:23 编辑如题，小弟建模后（模型类似于“葫芦串”的悬臂梁）做模态分析，期间有一个划分网格的警告，忽略后直接进行模态分析。提取前6阶振型如下：
LOCATION VALUE
1 1 1 8.10931395
2 1 1 8.53387987
3 1 1 44.2123363
4 1 1 46.5583388
5 1 1 86.8128668
6 1 1 119.321525
逐一观察振型，居然没有扭转，不知道是哪个环节出了问题。哪位前辈有经验可否告知？
回复 1: mp2625 的帖子
我在想是不是因为我只用了这根从上至下的柱子，且柱子截面18*19的尺寸近似对称，每个“葫芦”也是完全对称的。
会不会是说结构太对称，会没有扭转振型呢？ 没有扭转振型？怎么看出来的？你给出的数据是关于什么的？ 回复 3: 凌绝顶 的帖子
恩 我查看振型图看出来的，前6阶全部是弯曲。从频率分布也可以看出，每两阶的频率比较靠近，如果有三个频率比较靠近的话，才会出现扭转。命令流可以贴在下面：
命令流如下：
FINISH
/clear
/title,huluchuan
/PREP7 !进入前处理
ET,1,SOLID92
MP,EX,1,72000000 !弹性模量
MP,DENS,1,2.85e-6 !密度
MP,NUXY,1,0.333 !泊松比
!*****************函数赋值，参数调节*******************!
!建立8层“葫芦”外形坐标值(数组太长会导致出错，因此把外形坐标拆成3个数组分装)
*dim,A,array,18
!给数组每个元素赋值
A(1)=52.0,35.8,50,35.8,50,43.13,50.2,34.5,47.6,34.5,47.6,41.6,48.27,33.1,45.6,33.1,45.6,39.90
*dim,B,array,18
!给数组每个元素赋值
B(1)=46.3,31.8,43.7,31.8,43.7,38.4,44.5,30.5,41.8,30.5,41.8,36.8,42.5,29.1,40.0,29.1,40.0,35.1
*dim,C,array,12
!给数组每个元素赋值
C(1)=40.6,27.8,38.2,27.8,38.2,33.6,38.7,26.4,36.1,26.4,36.1,32
!由于蒙皮的厚度折算到模型中只有0.8mm，而模型蒙皮厚度通常为2mm因此需要补偿,x,y坐标均减小2mm
*do,i,1,18
A(i)=A(i)-2
B(i)=B(i)-2
*enddo
*do,i,1,12
C(i)=C(i)-2
*enddo
!建立每层所在高度数组
*dim,H,array,9
H(1)=73,179,298,411,523,641,753,867,985
!柱子的长宽高数组
*dim,Z,array,3
Z(1)=18,19,985
!柱子中心在楼板的坐标
*dim,WZ,array,2
WZ(1)=0,0
!在“葫芦”上挖洞的中心的坐标
*dim,DZX,array,8
DZX(1)=30,30,30,30,30,30,26,26
!“葫芦”上挖洞的尺寸
*dim,dong,array,8
dong(1)=18.6,11.4,11.6,16.4,10.0,14.0,9.4,10.6
!*****************************************
!建立“葫芦串”每个块体的厚度数组
*dim,KH,array,8
KH(1)=40,45,55,50,45,40,30,30
!*******************************************
!******************************************************!
!截面四边圆弧的半径
*set,R,533.3
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!定义1到8层面!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*do,i,1,3
k,1+(i-1)*24,-A(1+(i-1)*6),-A(2+(i-1)*6),H(i)
k,2+(i-1)*24,-A(3+(i-1)*6),-A(4+(i-1)*6),H(i)
k,3+(i-1)*24,-A(5+(i-1)*6),-A(6+(i-1)*6),H(i)
k,4+(i-1)*24,-A(6+(i-1)*6),-A(5+(i-1)*6),H(i)
k,5+(i-1)*24,-A(4+(i-1)*6),-A(3+(i-1)*6),H(i)
k,6+(i-1)*24,-A(2+(i-1)*6),-A(1+(i-1)*6),H(i)
k,7+(i-1)*24,A(2+(i-1)*6),-A(1+(i-1)*6),H(i)
k,8+(i-1)*24,A(4+(i-1)*6),-A(3+(i-1)*6),H(i)
k,9+(i-1)*24,A(6+(i-1)*6),-A(5+(i-1)*6),H(i)
k,10+(i-1)*24,A(5+(i-1)*6),-A(6+(i-1)*6),H(i)
k,11+(i-1)*24,A(3+(i-1)*6),-A(4+(i-1)*6),H(i)
k,12+(i-1)*24,A(1+(i-1)*6),-A(2+(i-1)*6),H(i)
k,13+(i-1)*24,A(1+(i-1)*6),A(2+(i-1)*6),H(i)
k,14+(i-1)*24,A(3+(i-1)*6),A(4+(i-1)*6),H(i)
k,15+(i-1)*24,A(5+(i-1)*6),A(6+(i-1)*6),H(i)
k,16+(i-1)*24,A(6+(i-1)*6),A(5+(i-1)*6),H(i)
k,17+(i-1)*24,A(4+(i-1)*6),A(3+(i-1)*6),H(i)
k,18+(i-1)*24,A(2+(i-1)*6),A(1+(i-1)*6),H(i)
k,19+(i-1)*24,-A(2+(i-1)*6),A(1+(i-1)*6),H(i)
k,20+(i-1)*24,-A(4+(i-1)*6),A(3+(i-1)*6),H(i)
k,21+(i-1)*24,-A(6+(i-1)*6),A(5+(i-1)*6),H(i)
k,22+(i-1)*24,-A(5+(i-1)*6),A(6+(i-1)*6),H(i)
k,23+(i-1)*24,-A(3+(i-1)*6),A(4+(i-1)*6),H(i)
k,24+(i-1)*24,-A(1+(i-1)*6),A(2+(i-1)*6),H(i)
l,1+(i-1)*24,2+(i-1)*24
l,2+(i-1)*24,3+(i-1)*24
l,3+(i-1)*24,4+(i-1)*24
l,4+(i-1)*24,5+(i-1)*24
l,5+(i-1)*24,6+(i-1)*24
larc,6+(i-1)*24,7+(i-1)*24,18+(i-1)*24,R
l,7+(i-1)*24,8+(i-1)*24
l,8+(i-1)*24,9+(i-1)*24
l,9+(i-1)*24,10+(i-1)*24
l,10+(i-1)*24,11+(i-1)*24
l,11+(i-1)*24,12+(i-1)*24
larc,12+(i-1)*24,13+(i-1)*24,24+(i-1)*24,R
l,13+(i-1)*24,14+(i-1)*24
l,14+(i-1)*24,15+(i-1)*24
l,15+(i-1)*24,16+(i-1)*24
l,16+(i-1)*24,17+(i-1)*24
l,17+(i-1)*24,18+(i-1)*24
larc,18+(i-1)*24,19+(i-1)*24,5+(i-1)*24,R
l,19+(i-1)*24,20+(i-1)*24
l,20+(i-1)*24,21+(i-1)*24
l,21+(i-1)*24,22+(i-1)*24
l,22+(i-1)*24,23+(i-1)*24
l,23+(i-1)*24,24+(i-1)*24
larc,24+(i-1)*24,1+(i-1)*24,11+(i-1)*24,R
*enddo
*do,i,1,3
k,1+(i+2)*24,-B(1+(i-1)*6),-B(2+(i-1)*6),H(i+3)
k,2+(i+2)*24,-B(3+(i-1)*6),-B(4+(i-1)*6),H(i+3)
k,3+(i+2)*24,-B(5+(i-1)*6),-B(6+(i-1)*6),H(i+3)
k,4+(i+2)*24,-B(6+(i-1)*6),-B(5+(i-1)*6),H(i+3)
k,5+(i+2)*24,-B(4+(i-1)*6),-B(3+(i-1)*6),H(i+3)
k,6+(i+2)*24,-B(2+(i-1)*6),-B(1+(i-1)*6),H(i+3)
k,7+(i+2)*24,B(2+(i-1)*6),-B(1+(i-1)*6),H(i+3)
k,8+(i+2)*24,B(4+(i-1)*6),-B(3+(i-1)*6),H(i+3)
k,9+(i+2)*24,B(6+(i-1)*6),-B(5+(i-1)*6),H(i+3)
k,10+(i+2)*24,B(5+(i-1)*6),-B(6+(i-1)*6),H(i+3)
k,11+(i+2)*24,B(3+(i-1)*6),-B(4+(i-1)*6),H(i+3)
k,12+(i+2)*24,B(1+(i-1)*6),-B(2+(i-1)*6),H(i+3)
k,13+(i+2)*24,B(1+(i-1)*6),B(2+(i-1)*6),H(i+3)
k,14+(i+2)*24,B(3+(i-1)*6),B(4+(i-1)*6),H(i+3)
k,15+(i+2)*24,B(5+(i-1)*6),B(6+(i-1)*6),H(i+3)
k,16+(i+2)*24,B(6+(i-1)*6),B(5+(i-1)*6),H(i+3)
k,17+(i+2)*24,B(4+(i-1)*6),B(3+(i-1)*6),H(i+3)
k,18+(i+2)*24,B(2+(i-1)*6),B(1+(i-1)*6),H(i+3)
k,19+(i+2)*24,-B(2+(i-1)*6),B(1+(i-1)*6),H(i+3)
k,20+(i+2)*24,-B(4+(i-1)*6),B(3+(i-1)*6),H(i+3)
k,21+(i+2)*24,-B(6+(i-1)*6),B(5+(i-1)*6),H(i+3)
k,22+(i+2)*24,-B(5+(i-1)*6),B(6+(i-1)*6),H(i+3)
k,23+(i+2)*24,-B(3+(i-1)*6),B(4+(i-1)*6),H(i+3)
k,24+(i+2)*24,-B(1+(i-1)*6),B(2+(i-1)*6),H(i+3)
l,1+(i+2)*24,2+(i+2)*24
l,2+(i+2)*24,3+(i+2)*24
l,3+(i+2)*24,4+(i+2)*24
l,4+(i+2)*24,5+(i+2)*24
l,5+(i+2)*24,6+(i+2)*24
larc,6+(i+2)*24,7+(i+2)*24,18+(i+2)*24,R
l,7+(i+2)*24,8+(i+2)*24
l,8+(i+2)*24,9+(i+2)*24
l,9+(i+2)*24,10+(i+2)*24
l,10+(i+2)*24,11+(i+2)*24
l,11+(i+2)*24,12+(i+2)*24
larc,12+(i+2)*24,13+(i+2)*24,24+(i+2)*24,R
l,13+(i+2)*24,14+(i+2)*24
l,14+(i+2)*24,15+(i+2)*24
l,15+(i+2)*24,16+(i+2)*24
l,16+(i+2)*24,17+(i+2)*24
l,17+(i+2)*24,18+(i+2)*24
larc,18+(i+2)*24,19+(i+2)*24,5+(i+2)*24,R
l,19+(i+2)*24,20+(i+2)*24
l,20+(i+2)*24,21+(i+2)*24
l,21+(i+2)*24,22+(i+2)*24
l,22+(i+2)*24,23+(i+2)*24
l,23+(i+2)*24,24+(i+2)*24
larc,24+(i+2)*24,1+(i+2)*24,11+(i+2)*24,R
*enddo
*do,i,1,2
k,1+(i+5)*24,-C(1+(i-1)*6),-C(2+(i-1)*6),H(i+6)
k,2+(i+5)*24,-C(3+(i-1)*6),-C(4+(i-1)*6),H(i+6)
k,3+(i+5)*24,-C(5+(i-1)*6),-C(6+(i-1)*6),H(i+6)
k,4+(i+5)*24,-C(6+(i-1)*6),-C(5+(i-1)*6),H(i+6)
k,5+(i+5)*24,-C(4+(i-1)*6),-C(3+(i-1)*6),H(i+6)
k,6+(i+5)*24,-C(2+(i-1)*6),-C(1+(i-1)*6),H(i+6)
k,7+(i+5)*24,C(2+(i-1)*6),-C(1+(i-1)*6),H(i+6)
k,8+(i+5)*24,C(4+(i-1)*6),-C(3+(i-1)*6),H(i+6)
k,9+(i+5)*24,C(6+(i-1)*6),-C(5+(i-1)*6),H(i+6)
k,10+(i+5)*24,C(5+(i-1)*6),-C(6+(i-1)*6),H(i+6)
k,11+(i+5)*24,C(3+(i-1)*6),-C(4+(i-1)*6),H(i+6)
k,12+(i+5)*24,C(1+(i-1)*6),-C(2+(i-1)*6),H(i+6)
k,13+(i+5)*24,C(1+(i-1)*6),C(2+(i-1)*6),H(i+6)
k,14+(i+5)*24,C(3+(i-1)*6),C(4+(i-1)*6),H(i+6)
k,15+(i+5)*24,C(5+(i-1)*6),C(6+(i-1)*6),H(i+6)
k,16+(i+5)*24,C(6+(i-1)*6),C(5+(i-1)*6),H(i+6)
k,17+(i+5)*24,C(4+(i-1)*6),C(3+(i-1)*6),H(i+6)
k,18+(i+5)*24,C(2+(i-1)*6),C(1+(i-1)*6),H(i+6)
k,19+(i+5)*24,-C(2+(i-1)*6),C(1+(i-1)*6),H(i+6)
k,20+(i+5)*24,-C(4+(i-1)*6),C(3+(i-1)*6),H(i+6)
k,21+(i+5)*24,-C(6+(i-1)*6),C(5+(i-1)*6),H(i+6)
k,22+(i+5)*24,-C(5+(i-1)*6),C(6+(i-1)*6),H(i+6)
k,23+(i+5)*24,-C(3+(i-1)*6),C(4+(i-1)*6),H(i+6)
k,24+(i+5)*24,-C(1+(i-1)*6),C(2+(i-1)*6),H(i+6)
l,1+(i+5)*24,2+(i+5)*24
l,2+(i+5)*24,3+(i+5)*24
l,3+(i+5)*24,4+(i+5)*24
l,4+(i+5)*24,5+(i+5)*24
l,5+(i+5)*24,6+(i+5)*24
larc,6+(i+5)*24,7+(i+5)*24,18+(i+5)*24,R
l,7+(i+5)*24,8+(i+5)*24
l,8+(i+5)*24,9+(i+5)*24
l,9+(i+5)*24,10+(i+5)*24
l,10+(i+5)*24,11+(i+5)*24
l,11+(i+5)*24,12+(i+5)*24
larc,12+(i+5)*24,13+(i+5)*24,24+(i+5)*24,R
l,13+(i+5)*24,14+(i+5)*24
l,14+(i+5)*24,15+(i+5)*24
l,15+(i+5)*24,16+(i+5)*24
l,16+(i+5)*24,17+(i+5)*24
l,17+(i+5)*24,18+(i+5)*24
larc,18+(i+5)*24,19+(i+5)*24,5+(i+5)*24,R
l,19+(i+5)*24,20+(i+5)*24
l,20+(i+5)*24,21+(i+5)*24
l,21+(i+5)*24,22+(i+5)*24
l,22+(i+5)*24,23+(i+5)*24
l,23+(i+5)*24,24+(i+5)*24
larc,24+(i+5)*24,1+(i+5)*24,11+(i+5)*24,R
*enddo
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!直接用线生成面会出现问题，故用简单命令生成面!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/PREP7
FLST,2,24,4
FITEM,2,18
FITEM,2,17
FITEM,2,16
FITEM,2,15
FITEM,2,14
FITEM,2,13
FITEM,2,12
FITEM,2,11
FITEM,2,10
FITEM,2,9
FITEM,2,8
FITEM,2,7
FITEM,2,6
FITEM,2,5
FITEM,2,4
FITEM,2,3
FITEM,2,2
FITEM,2,1
FITEM,2,24
FITEM,2,23
FITEM,2,22
FITEM,2,21
FITEM,2,20
FITEM,2,19
AL,P51X
FLST,2,24,4
FITEM,2,36
FITEM,2,35
FITEM,2,34
FITEM,2,33
FITEM,2,32
FITEM,2,31
FITEM,2,30
FITEM,2,29
FITEM,2,28
FITEM,2,27
FITEM,2,26
FITEM,2,25
FITEM,2,48
FITEM,2,47
FITEM,2,46
FITEM,2,45
FITEM,2,44
FITEM,2,43
FITEM,2,42
FITEM,2,41
FITEM,2,40
FITEM,2,39
FITEM,2,38
FITEM,2,37
AL,P51X
FLST,2,24,4
FITEM,2,60
FITEM,2,59
FITEM,2,58
FITEM,2,57
FITEM,2,56
FITEM,2,55
FITEM,2,54
FITEM,2,53
FITEM,2,52
FITEM,2,51
FITEM,2,50
FITEM,2,49
FITEM,2,72
FITEM,2,71
FITEM,2,70
FITEM,2,69
FITEM,2,68
FITEM,2,67
FITEM,2,66
FITEM,2,65
FITEM,2,64
FITEM,2,63
FITEM,2,62
FITEM,2,61
AL,P51X
FLST,2,24,4
FITEM,2,92
FITEM,2,91
FITEM,2,90
FITEM,2,89
FITEM,2,88
FITEM,2,87
FITEM,2,86
FITEM,2,85
FITEM,2,84
FITEM,2,83
FITEM,2,82
FITEM,2,81
FITEM,2,80
FITEM,2,79
FITEM,2,78
FITEM,2,77
FITEM,2,76
FITEM,2,75
FITEM,2,74
FITEM,2,73
FITEM,2,96
FITEM,2,95
FITEM,2,94
FITEM,2,93
AL,P51X
FLST,2,24,4
FITEM,2,120
FITEM,2,119
FITEM,2,118
FITEM,2,117
FITEM,2,116
FITEM,2,115
FITEM,2,114
FITEM,2,113
FITEM,2,112
FITEM,2,111
FITEM,2,110
FITEM,2,109
FITEM,2,108
FITEM,2,107
FITEM,2,106
FITEM,2,105
FITEM,2,104
FITEM,2,103
FITEM,2,102
FITEM,2,101
FITEM,2,100
FITEM,2,99
FITEM,2,98
FITEM,2,97
AL,P51X
FLST,2,24,4
FITEM,2,144
FITEM,2,143
FITEM,2,142
FITEM,2,141
FITEM,2,140
FITEM,2,139
FITEM,2,138
FITEM,2,137
FITEM,2,136
FITEM,2,135
FITEM,2,134
FITEM,2,133
FITEM,2,132
FITEM,2,131
FITEM,2,130
FITEM,2,129
FITEM,2,128
FITEM,2,127
FITEM,2,126
FITEM,2,125
FITEM,2,124
FITEM,2,123
FITEM,2,122
FITEM,2,121
AL,P51X
FLST,2,24,4
FITEM,2,168
FITEM,2,167
FITEM,2,166
FITEM,2,165
FITEM,2,164
FITEM,2,163
FITEM,2,162
FITEM,2,161
FITEM,2,160
FITEM,2,159
FITEM,2,158
FITEM,2,157
FITEM,2,156
FITEM,2,155
FITEM,2,154
FITEM,2,153
FITEM,2,152
FITEM,2,151
FITEM,2,150
FITEM,2,149
FITEM,2,148
FITEM,2,147
FITEM,2,146
FITEM,2,145
AL,P51X
FLST,2,24,4
FITEM,2,192
FITEM,2,191
FITEM,2,190
FITEM,2,189
FITEM,2,188
FITEM,2,187
FITEM,2,186
FITEM,2,185
FITEM,2,184
FITEM,2,183
FITEM,2,182
FITEM,2,181
FITEM,2,180
FITEM,2,179
FITEM,2,178
FITEM,2,177
FITEM,2,176
FITEM,2,175
FITEM,2,174
FITEM,2,173
FITEM,2,172
FITEM,2,171
FITEM,2,170
FITEM,2,169
AL,P51X
APLOT
!挖洞
*do,i,1,8
WPOFFS,DZX(i),0,H(i)
RECTNG,-dong(i)/2,dong(i)/2,-dong(i)/2,dong(i)/2
WPAVE,0,0,0
*enddo
!挖洞
*do,i,1,8
WPOFFS,0,DZX(i),H(i)
RECTNG,-dong(i)/2,dong(i)/2,-dong(i)/2,dong(i)/2
WPAVE,0,0,0
*enddo
!布尔操作挖掉孔
*do,i,1,8
ASBA,i,i+8,,keep,keep
*enddo
*do,i,1,8
ASBA,i+24,i+16,,keep,keep
*enddo
*do,i,1,8
ASBA,i+24,i+16,,keep,keep
*enddo
adele,1,32
numcmp,area
!挖洞
*do,i,1,8
WPOFFS,-DZX(i),0,H(i)
RECTNG,-dong(i)/2,dong(i)/2,-dong(i)/2,dong(i)/2
WPAVE,0,0,0
*enddo
*do,i,1,8
WPOFFS,0,-DZX(i),H(i)
RECTNG,-dong(i)/2,dong(i)/2,-dong(i)/2,dong(i)/2
WPAVE,0,0,0
*enddo
!布尔操作挖掉孔
*do,i,1,8
ASBA,i,i+8,,keep,keep
*enddo
*do,i,1,8
ASBA,i+24,i+16,,keep,keep
*enddo
adele,1,32
numcmp,area
!将8个面i沿法线方向平移KH(i),生成体
*do,i,1,8
VOFFST,i,KH(i)
*enddo
!生成1根柱子,把所有实体组合起来成一个实体
BLC5,WZ(1),WZ(2),Z(1),Z(2),Z(3)
VADD,all
!划分网格
type,1
mat,1
esys,0
ESIZE,15 !控制单元边长进行网格划分
!MSHAPE,0 !定义单元划分形状
MSHKEY,0 !自由网格划分
MOPT,TRANS,2
VMESH,all !以某个单元进行划分
FINISH
!显示设置
/ANGLE,1,-30,ZS,1
/ANGLE,1,-60,XS,1
!显示线
!kplot
!lplot
!aplot
vplot
!显示单元编号
!/PNUM,kp,1
!/PNUM,line,1
!/PNUM,AREA,1
/PNUM,VOLUME,1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!进行模态分析并且获得振型和频率!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*SET,aa,6!求解前a阶模态
/solu
anty,modal
asel,s,loc,z,-0.1,0.1
da,all,all
allsel,all
MODOPT,SUBSP,aa
mxpand,aa,,yes
LUMPM,1 !相对质量矩阵进行归一化处理
solv
/POST1
!定义频率数组
*DIM,FQ,ARRAY,aa,1!定义数组
*DO,I11,1,aa
*GET,FQ(I11,1),MODE,I11,FREQ
*END DO
*STATUS,FQ,1,,1,,1,,
*CFOPEN,FRQ,dat
*VWRITE,FQ(1)
(F15.8)
*CFCLOS
回复 4: mp2625 的帖子
这样是看不出来的！从振型图中能看出扭转吗？我觉得你应该看看计算得出来的每个节点的位移数据，而不只是看阵型图。每两个或三个隔得近也并不能说明任何问题。 回复 6 # 凌绝顶 的帖子
哦 你的意思是振型图上无法看出细微的扭转？即需要查看节点位移数据来推断是吧
我先试试，谢谢！ 回复 7 # mp2625 的帖子
是这个意思 回复 6 # 凌绝顶 的帖子
通过仔细检查，第3阶节点位移如下，分别是UX UY UZ 可以看到 第三阶振型中UX比UY大得多，因此确实无扭转，
分析：
1是我的模型太过对称；
2。还是我模态分析的方法不对？
1 -0.30046 0.11084E-02 0.15269E-01 0.30085
2 -0.40250 0.15562E-02 0.84352E-02 0.40259
3 -0.31291 0.13089E-02 0.14777E-01 0.31326
4 -0.32499 0.14045E-02 0.14265E-01 0.32530
5 -0.33659 0.14695E-02 0.13720E-01 0.33688
6 -0.34774 0.15306E-02 0.13147E-01 0.34800 回复 9 # mp2625 的帖子
如果没有定义其它约束的话，每个节点应该有六个自由度才对嘛，你这几个自由度？四个？ 回复 10 # 凌绝顶 的帖子
我建的实体单元，节点就是这3个自由度 利用这3个自由度可以得到全部6个分量的吧
我现在不需要计算 单单观察UX UY 也可以基本判断RZ的大小 mp2625 发表于 2010-11-6 11:30 static/image/common/back.gif
回复 10 # 凌绝顶 的帖子
我建的实体单元，节点就是这3个自由度 利用这3个自由度可以得到全部6个分量的吧 ...
1 -0.30046 0.11084E-02 0.15269E-01 0.30085
2 -0.40250 0.15562E-02 0.84352E-02 0.40259
3 -0.31291 0.13089E-02 0.14777E-01 0.31326
4 -0.32499 0.14045E-02 0.14265E-01 0.32530
5 -0.33659 0.14695E-02 0.13720E-01 0.33688
6 -0.34774 0.15306E-02 0.13147E-01 0.34800
从这里可以看出至少有四个自由度嘛！一般情况下梁的扭转频率较其它自由度来讲本来就很大。建议你思考周全点，别轻易下结论！ 回复 12 # 凌绝顶 的帖子
呵呵 我之前认为第4个是一个总向量并不是自由度你的建议有道理我对振型方面的知识还需要多补补感谢你能和我讨论！ 楼主多算几阶，或许就出现了呢{:{25}:} 回复 14 # Rainyboy 的帖子
对，多算几阶的话，扭转振型是一定会出现的。但目前的情况是，我希望能在第三阶出现扭转振型（模拟某高层建筑），需要在建模上如何调整呢？因为振型计算涉及到刚度矩阵、质量矩阵等，计算的部分很复杂，因此希望得到一些定性的建议。谢谢
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