wabb0512 发表于 2010-11-27 11:17

跨中位移时程曲线的异常

请问大家，我这个跨中位移的时程曲线怎么会是这样子啊，太有规律了，做的是一个张弦桁架结构的地震波下瞬态分析，

wabb0512 发表于 2010-11-27 11:21

模型是这样的

奇怪的是当我i把节点荷载去掉之后，跨中位移时程曲线变成了我想要的形式，尽管不知道对不对


wabb0512 发表于 2010-11-27 11:22

模型是这样的

wabb0512 发表于 2010-11-27 11:25

命令流如下
/COM，Structural
/PREP7
ET,1,beam4
ET,2,link8
ET,3,link10
R,1,2.74889e-3,0
R,2,5.34071e-3,0
R,3,1.15108e-2,0
R,4,5.44202e-3,0
R,5,2.060885e-2,4.33702e-4,4.33702e-4,0.426，0.426
R,6,3.015929e-2,8.70095e-4,8.70095e-4,0.5，0.5
R,7,2.363e-3,2.159e-3
MP,EX,1,206e9
MP,DENS,1,7850
MP,PRXY,1,0.3
MP,EX,2,196e9
MP,DENS,2,7850

N,1,1108.207,39.690,27.818,
N,2,1096.211,39.690,28.058,
N,3,1072.297,39.690,26.206,
N,4,1084.224,39.690,27.520,
N,5,1059.254,37.190,23.861,
N,6,1063.421,37.190,24.715,
N,7,1121.389,37.190,26.653,
N,8,1117.181,37.190,27.128，
N,9,1114.194,37.190,27.407,
N,10,1111.202,37.190,27.637,
N,11,1108.207,37.190,27.818,
N,12,1105.210,37.190,27.951,
N,13,1102.211,37.190,28.035,
N,14,1099.211,37.190,28.071,
N,15,1096.211,37.190,28.058,
N,16,1093.211,37.190,27.996,
N,17,1090.213,37.190,27.886,
N,18,1087.217,37.190,27.727,
N,19,1084.224,37.190,27.520,
N,20,1081.234,37.190,27.264,
N,21,1078.250,37.190,26.960,
N,22,1075.270,37.190,26.607,
N,23,1072.297,37.190,26.206,
N,24,1069.330,37.190,25.757,
N,25,1066.372,37.190,25.260,
N,26,1060.480,38.440,26.166,
N,27,1120.163,38.440,28.815,
N,28,1118.673,38.440,28.983,
N,29,1112.698,38.440,29.534,
N,30,1106.710,38.440,29.893,
N,31,1100.712,38.440,30.059,
N,32,1094.713,38.440,30.034,
N,33,1088.717,38.440,29.816,
N,34,1082.732,38.440,29.406,
N,35,1064.897,38.440,27.028,
N,36,1076.762,38.440,28.804,
N,37,1070.815,38.440,28.011,
N,38,1066.372,39.690,25.260,
N,39,1114.194,39.690,27.407,
N,40,1102.211,39.690,28.035,
N,41,1090.213,39.690,27.886,
N,42,1078.250,39.690,26.960,
N,43,1061.706,39.690,24.376,
N,44,1120.163,38.440,24.815,
N,45,1117.181,38.440,27.128,
N,46,1063.421,38.440,24.715,
N,47,1115.688,38.440,29.282,
N,48,1109.705,38.440,29.737,
N,49,1103.712,38.440,30.000,
N,50,1097.712,38.440,30.070,
N,51,1091.714,38.440,29.949,
N,52,1085.723,38.440,29.635,
N,53,1079.744,38.440,29.129,
N,54,1073.785,38.440,28.431,
N,55,1067.852,38.440,27.543,
N,56,1061.950,38.440,26.465,
N,57,1099.211,39.690,28.071,
N,58,1081.234,39.690,27.264,
N,59,1117.181,39.690,27.128,
N,60,1118.937,39.690,26.942,
N,61,1060.480,38.440,22.166,
N,62,1063.421,39.690,24.715,
N,63,1111.202,39.690,27.637,
N,64,1105.210,39.690,27.951,
N,65,1093.211,39.690,27.996,
N,66,1087.217,39.690,27.727,
N,67,1075.270,39.690,26.607,
N,68,1069.330,39.690,25.757,
N,69,1072.292,38.440,23.450,
N,70,1081.234,38.440,22.843,
N,71,1090.213,38.440,22.897,
N,72,1099.211,38.440,23.620,
N,73,1108.207,38.440,25.025,

TYPE,1
REAL,5
MAT,1
E,5,6,
E,43,62,
E,6,25,
E,62,38,
E,25,24,
E,38,68,
E,24,23
E,68,3,
E,23,22,
E,3,67,
E,22,21,
E,67,42,
E,21,20,
E,42,58,
E,20,19,
E,58,4,
E,19,18,
E,4,66,
E,18,17,
E,66,41,
E,17,16,
E,41,65,
E,16,15,
E,65,2,
E,15,14,
E,2,57,
E,14,13,
E,57,40,
E,13,12,
E,40,64,
E,12,11,
E,64,1,
E,11,10,
E,1,63,
E,10,9,
E,63,39,
E,9,8,
E,39,59,
E,59,60,
E,8,7,

TYPE,1
REAL,6
MAT,1
E,26,56,
E,56,35,
E,35,55,
E,55,37,
E,37,54,
E,54,36,
E,36,53,
E,53,34,
E,34,52,
E,52,33,
E,33,51,
E,51,32,
E,32,50,
E,50,31,
E,31,49,
E,49,30,
E,30,48,
E,48,29,
E,29,47,
E,47,28,
E,28,27,

TYPE,2
REAL,1
MAT,1
E,43,46,
E,38,24,
E,24,55,
E,24,37,
E,24,3,
E,68,55,
E,68,37,
E,23,37,
E,23,54,
E,3,37,
E,3,54,
E,3,22,
E,22,54,
E,22,36,
E,22,42,
E,67,54,
E,67,36,
E,21,36,
E,21,53,
E,42,36,
E,42,53,
E,42,20,
E,20,53,
E,20,34,
E,20,4,
E,58,53,
E,58,34,
E,19,34,
E,19,52,
E,4,34,
E,4,52,
E,4,18,
E,18,52,
E,18,33,
E,18,41,
E,66,52,
E,66,33,
E,17,33,
E,17,51,
E,41,33,
E,41,51,
E,41,16,
E,16,51,
E,16,32,
E,16,2,
E,65,32,
E,65,51,
E,15,32,
E,15,50,
E,2,50,
E,2,14,
E,14,50,
E,14,31,
E,14,40,
E,57,50,
E,57,31,
E,13,31,
E,13,49,
E,40,31,
E,40,49,
E,40,12,
E,12,49,
E,12,30,
E,12,1,
E,64,49,
E,64,30,
E,11,30,
E,11,48,
E,1,30,
E,1,48,
E,1,10,
E,10,48,
E,10,39,
E,63,48,
E,39,45,
E,45,39,
E,45,60,


TYPE,2
REAL,2
MAT,1
E,6,46,
E,46,62,
E,25,38,
E,25,35,
E,25,55,
E,38,35,
E,38,55,
E,24,68,
E,23,3,
E,3,23,
E,22,67,
E,21,42,
E,20,58,
E,19,4,
E,18,66,
E,17,41,
E,16,65,
E,15,2,
E,14,57,
E,13,40,
E,12,64,
E,11,1,
E,10,63,
E,10,29,
E,63,29,
E,9,39,
E,9,29,
E,9,47,
E,39,29,
E,39,47,
E,8,45,
E,45,59,

TYPE,2
REAL,3
MAT,1
E,61,6,
E,61,46,
E,61,62,
E,61,5,
E,61,43,
E,5,46,
E,5,56,
E,5,26,
E,5,43,
E,43,26,
E,43,56,
E,6,56,
E,6,35,
E,46,56,
E,46,38,
E,46,25,
E,62,56,
E,62,35,
E,9,45,
E,8,47,
E,8,28,
E,8,44,
E,45,28,
E,45,7,
E,45,44,
E,59,47,
E,59,28,
E,59,44,
E,44,60,
E,44,7,
E,60,28,
E,60,27,
E,60,7,
E,28,7,
E,7,27,

TYPE,2
REAL,4
MAT,1
E,23,69,
E,3,69,
E,58,70,
E,17,71,
E,41,71,
E,14,72,
E,57,72,
E,11,73,
E,1,73,
E,20,70,

TYPE,3
REAL,7
MAT,2
E,46,69,
E,45,73,
E,69,70,
E,70,71,
E,71,72,
E,72,73,
FINISH
/SOL
D,1,UY,,,43,1
D,60,UY,0
D,61,UX,0,,,,UY,UZ
D,44,UX,0,,,,UY,UZ
F,26,FZ,-21262.5
F,27,FZ,-21262.5
F,43,FZ,-21262.5
F,60,FZ,-21262.5
F,1,FZ,-42525,,4,1
F,28,FZ,-42525,,42,1
F,47,FZ,-42525,,68,1
ALLSEL,ALL
ACEL,0,0,9.8
ANTYPE,STATIC
SOLVE
FINISH

/post1
ETABLE,SUO,LS,1
FINISH

/SOL
ANTYPE,MODAL
MODOPT,SUBSP,10
MXPAND,10, , ,1
PSTRES,1
MODOPT,SUBSP,10,0,0, ,OFF   
SUBOPT,8,4,14,0,0,ALL
SOLVE
FINISH
*GET,FREQ1,MODE,1,FREQ
/CONFIG,NRES,20000
*SET,NT,500
*SET,DT,0.02
*SET,DAMPRATIO,0.01
*DIM,AC_X,,NT
*DIM,AC_Y,,NT
*DIM,AC_Z,,NT
*VREAD,AC_X(1),X,TXT,,JIK,1,NT
(E11.4)
*VREAD,AC_Y(1),Y,TXT,,JIK,1,NT
(E11.4)
*VREAD,AC_Z(1),Z,TXT,,JIK,1,NT
(E11.4)
/SOL
ANTYPE,TRANS
TRNOPT,FULL
ALPHAD,2*DAMPRATIO*FREQ1*2*3.1415926
BETAD,2*DAMPRATIO/(FREQ1*2*3.1415926)
*DO,I,1,NT
ACEL,AC_X(I),AC_Y(I),AC_Z(I)
TIME,I*DT
OUTRES,ALL,ALL
SOLVE
*ENDDO
FINISH

Rainyboy 发表于 2010-11-27 14:12

本帖最后由 Rainyboy 于 2010-11-27 14:18 编辑

回复 4 # wabb0512 的帖子

i节点是哪个节点啊？
是指
*DO,I,1,NT
ACEL,AC_X(I),AC_Y(I),AC_Z(I)
TIME,I*DT
这段APDL么？要是都去掉了楼主岂不是在计算自由振动……
还有啊，我看楼主最后的瞬态动力学求解APDL：


ANTYPE,TRANS
TRNOPT,FULL
ALPHAD,2*DAMPRATIO*FREQ1*2*3.1415926
BETAD,2*DAMPRATIO/(FREQ1*2*3.1415926)
*DO,I,1,NT
ACEL,AC_X(I),AC_Y(I),AC_Z(I)
TIME,I*DT
OUTRES,ALL,ALL
SOLVE
*ENDDO
FINISH


怎么没有打开时间积分选项：
TIMINT,ON


虽然最终的问题也许不是由于这个造成的，但是跟我想象的不太一样，希望楼主解释解释，共同学习，呵呵

wabb0512 发表于 2010-11-27 17:26

回复 5 # Rainyboy 的帖子

节点荷载是指施加在桁架节点上的荷载，是由屋面荷载转化来的，就是把下面的F命令流给去掉了，去掉之后的模型实际上就没有屋面恒载了，只有桁架本身的重力，在没有屋面恒载的情况下，结构的跨中竖向位移曲线符合实际，但加上F命令流后，即加上节点荷载后，跨中位移时程曲线就是第一幅图了，这明显不对，我也试过时间积分，应力钢化，大变形，问题不是出在这里好像（我觉得），问题好像出在节点荷载上（我觉得），那怎么才能在加上节点荷载的情况下得到正确的时程位移曲线呢，拜托大家了

F,26,FZ,-21262.5
F,27,FZ,-21262.5
F,43,FZ,-21262.5
F,60,FZ,-21262.5
F,1,FZ,-42525,,4,1
F,28,FZ,-42525,,42,1
F,47,FZ,-42525,,68,1

wabb0512 发表于 2010-11-27 17:40

初学ansys，命令流是一个一个写的，再附上节点图

wabb0512 发表于 2010-11-27 17:41

回复 7 # wabb0512 的帖子

wabb0512 发表于 2010-11-27 17:50

发现一个问题，没有节点荷载时，时程曲线在大约0值（较小值）附近振动，有节点荷载时在某一数值下振动，按照常理在某一数值下的振动形式应该和没有节点荷载时差不多，可是它却是很有规律的衰减了

wabb0512 发表于 2010-11-27 17:54

我再把节点荷载都减半试一试
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