ANSYS子结构模态分析例子讨论
我在网上下载了一个5层框架的子结构模态分析的例子，具体是在那个论坛下载的还真不记得了，如有冒犯请作者见谅！我将这个例子按上述例子标准的三个阶段进行了修改，但模态分析结果却相差甚远，不知道是哪儿的设置有问题，还请高手帮忙看看，谢谢！
我运行完原来的例子后发现如下几个问题：
1，采用SE求得的结构前5阶频率如下所示：
SET TIME/FREQ LOAD STEP SUBSTEPCUMULATIVE
1 0.10863E-01 1 1 1
2 0.17132E-01 1 2 2
3 0.68671E-01 1 3 3
4 0.68675E-01 1 4 4
5 0.10773 1 5 5
而不用SE直接求解，得到的前5阶自振频率为：
SET TIME/FREQ LOAD STEP SUBSTEPCUMULATIVE
11.0831 1 1 1
21.0831 1 2 2
31.7131 1 3 3
46.8670 1 4 4
56.8670 1 5 5
说明上述程序已经有问题了，还请大侠指点下问题出在哪里？
2，在用SE求解后，看错误文件，发现有这样的警告：
*** WARNING *** CP = 3.838 TIME= 16:45:09
STURM number= 2 should be 1
Probably initial shift greater than first mode or
Final Mode(s) is in a cluster.
*** WARNING *** CP = 3.869 TIME= 16:45:09
STURM number= 6 should be 5
Probably initial shift greater than first mode or
Final Mode(s) is in a cluster.
如果我用：MODOPT,LANB,5,0,100000, ,OFF，后就不会出现这个警告了。但结果还是有问题。
3，在最后用*GET命令看扩展后的频率时，结果全为零，见下图（见附件吧），不知何故。
另外，原例子是将plane42模拟的楼板全考虑为SE，而beam4模拟的柱子为非SE，而我为了熟悉子结构分析，就将先采用点、线、面建的第一层楼板及柱子作为非SE，而将上面4层柱子和板设为SE，就这么一个小小的改动，就出问题了，看来还是对子结构法不熟悉！
论坛上下载的源程序：
/CLEAR,NOSTART
/FILNAME,GEN
/PREP7
ANTYPE,SUBST ! SUBSTRUCTURE GENERATION PASS
SEOPT,GEN,2
ET,1,BEAM4
ET,2,PLANE42
R,1,0.3*0.3,0.3**4/12,0.3**4/12,0.3,0.3
MP,EX,1,20E11
MP,PRXY,1,0.3
MP,DENS,1,2500
k,1
k,2,3,0
k,3,3,3
k,4,0,3
kgen,2,all,,,,,4,4
l,1,5
l,2,6
l,3,7
l,4,8
lesize,4
lmesh,all
a,5,6,7,8
asel,all
type,2
esize,0.25
MSHK,1 ! MAPPED AREA MESH
MSHA,0,2D ! USING QUADS
AMESH,1 ! MESH AREA 2 WITH QUADRILATERALS
EGEN,5,2000,ALL,,,,,,,,,,4
NUMMRG,ALL
NUMCMP,ALL
!nsel,s,loc,z,0
!d,all,all
ALLSEL
NSEL,S,,,2,14,4
NSEL,A,,,182,191,3
NSEL,A,,,359,368,3
NSEL,A,,,536,545,3
NSEL,A,,,713,722,3
m,all,all
FINISH
/SOLU
ESEL,S,TYPE,,2
NSLE
EQSLV,SPARSE
SOLVE
SAVE ! SAVE SUBSTRUCTURE DATA BASE FOR EXPANSION PASS
FINISH
/CLEAR, NOSTART
/FILNAM,USE
/PREP7
ET,1,MATRIX50
ET,2,BEAM4
ET,3,PLANE42
R,1,0.3*0.3,0.3**4/12,0.3**4/12,0.3,0.3
R,2,
MP,EX,1,20E7
MP,PRXY,1,0.3
MP,DENS,1,2500
k,1
k,2,3,0
k,3,3,3
k,4,0,3
kgen,2,all,,,,,4,4
l,1,5
l,2,6
l,3,7
l,4,8
type,2
lesize,4
lmesh,all
a,5,6,7,8
asel,all
type,3
esize,0.25
MSHK,1 ! MAPPED AREA MESH
MSHA,0,2D ! USING QUADS
AMESH,1 ! MESH AREA 2 WITH QUADRILATERALS
EGEN,5,2000,ALL,,,,,,,,,,4
NUMMRG,NODE
NUMCMP,NODE
ACLEAR,ALL
ADELE,ALL
ESEL,S,TYPE,,3
EDELE,ALL
TYPE,1
SE,GEN
/SOLU
NSEL,S,LOC,Z,0
D,ALL,ALL
ALLSEL
ANTYPE,MODAL
MODOPT,SUBSP,5
MXPAND,5
ALLSEL
SOLVE
SAVE
FINISH
/CLEAR, NOSTART
/FILNAME,GEN
/PREP7
RESUME
/SOLU
ANTYPE,7
EXPASS,ON,YES ! EXPANSION PASS WITH ELEMENT SOLUTION
SEEXP,GEN,USE
OUTPR,NSOL,NONE ! DISPLACEMENT PRINTOUT CONTROL
OUTPR,ESOL,ALL
EXPSOL,1,5
SOLVE
FINISH
*GET,FREQ1,MODE,1,FREQ
*GET,FREQ2,MODE,2,FREQ
*GET,FREQ3,MODE,3,FREQ
*GET,FREQ4,MODE,4,FREQ
*GET,FREQ5,MODE,5,FREQ
自己修改后的程序
/CLEAR,NOSTART
/FILNAME,GEN
/PREP7
ET,1,BEAM4
ET,2,PLANE42
R,1,0.3*0.3,0.3**4/12,0.3**4/12,0.3,0.3
MP,EX,1,20E11
MP,PRXY,1,0.3
MP,DENS,1,2500
k,1
k,2,3,0
k,3,3,3
k,4,0,3
kgen,2,all,,,,,4,4
l,1,5
l,2,6
l,3,7
l,4,8
lesize,4
lmesh,all
a,5,6,7,8
asel,all
type,2
esize,0.25
MSHK,1 ! MAPPED AREA MESH
MSHA,0,2D ! USING QUADS
AMESH,1 ! MESH AREA 2 WITH QUADRILATERALS
EGEN,5,2000,ALL,,,,,,,,,,4
NUMMRG,ALL
NUMCMP,ALL
allsel,all
! dele non SE element-------------------自己修改的部分--------
aclear,all
adele,all
lclear,all
ldele,all
allsel,all
FINISH
/SOLU
ANTYPE,SUBST ! SUBSTRUCTURE GENERATION PASS
SEOPT,GEN,2
NSEL,S,,,182,191,3
NSEL,A,,,359,368,3
NSEL,A,,,536,545,3
NSEL,A,,,713,722,3
m,all,all
allsel,all
SOLVE
SAVE ! SAVE SUBSTRUCTURE DATA BASE FOR EXPANSION PASS
FINISH
/CLEAR, NOSTART
/FILNAM,USE
/PREP7
! create non super element part, which is deleted above，自己修改的部分
ET,1,BEAM4
ET,2,PLANE42
R,1,0.3*0.3,0.3**4/12,0.3**4/12,0.3,0.3
MP,EX,1,20E11
MP,PRXY,1,0.3
MP,DENS,1,2500
k,1
k,2,3,0
k,3,3,3
k,4,0,3
kgen,2,all,,,,,4,4
l,1,5
l,2,6
l,3,7
l,4,8
lesize,4
lmesh,all
a,5,6,7,8
asel,all
type,2
esize,0.25
MSHK,1 ! MAPPED AREA MESH
MSHA,0,2D ! USING QUADS
AMESH,1 ! MESH AREA 2 WITH QUADRILATERALS
ET,100,MATRIX50
TYPE,100
*GET,MaxNode,NODE,,NUM,MAX ! determine the max number of nodes
SETRAN,GEN,,MaxNode,GEN2 ! node number offset
SE,GEN2 ! Read in superelement matrix
fini
/SOLU
NSEL,S,LOC,Z,0
D,ALL,ALL
ALLSEL
ANTYPE,MODAL !there will be a trans analysis if modal changed to trais. only with some solving conditons.
MODOPT,LANB,5,0,100000, ,OFF
ALLSEL
SOLVE
SAVE
FINISH
/CLEAR, NOSTART
/FILNAME,GEN
/PREP7
RESUME
/SOLU
ANTYPE,7
EXPASS,ON,YES ! EXPANSION PASS WITH ELEMENT SOLUTION
SEEXP,GEN2,USE
OUTPR,NSOL,NONE ! DISPLACEMENT PRINTOUT CONTROL
OUTPR,ESOL,ALL
EXPSOL,1,1
SOLVE
FINISH
1，按自己的程序计算的结果为：
SET TIME/FREQ LOAD STEP SUBSTEPCUMULATIVE
10.0000 1 1 1
20.0000 1 2 2
30.0000 1 3 3
40.0000 1 4 4
5 0.29907E-04 1 5 5
我个人觉得是在导入SE时存在约束问题，因为计算的前4阶频率为零，第5阶也小的可怜。
2，在最后的*GET命令中，得到的频率值和原来的程序一样，全为零。
3，在整个程序运行完毕时仅有一个警告如下：
*** WARNING *** CP = 4.150 TIME= 16:59:58
Use pass step 1 substep 1 does not exist.
高人呢？急用啊！请指点一二！
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