 |
|
|
我想用ansys模拟斜拉桥拉索在简谐荷载激励下的振动问题， 在拉索7＃节点上，施加一正弦荷载作用60s，然后卸掉荷载，让拉索作自由衰减振动40s。
按照结构动力学的知识，初始施加荷载时，拉索振动包含稳态反应和瞬态反应两部分，由于阻尼的存在，瞬态反应将很快衰减至零，只剩下稳态反应，也就是说这时位移的振动幅值应当保持稳定。在30～60s这段时间内，应是稳态反应，然而，从ansys得到的位移时程曲线来看，曲线已经开始衰减了，等卸掉荷载后，曲线开始第二次衰减！why? 请高手们不吝指教，谢谢！
附命令流。
!拉索瞬态动力学分析
!无阻尼器拉索瞬态动力学分析
/prep7
!生成拉索S12节点坐标
!抛物线线型
n , 1 , 0 , 0
n , 2 , 2.5 , 1.05505
n , 3 , 5 , 2.1112
n , 4 , 7.5 , 3.16845
n , 5 , 10 , 4.2268
n , 6 , 12.5 , 5.28625
n , 7 , 15 , 6.3468
n , 8 , 17.5 , 7.40845
n , 9 , 20 , 8.4712
n , 10 , 22.5 , 9.53505
n , 11 , 25 , 10.6
n , 12 , 27.5 , 11.66605
n , 13 , 30 , 12.7332
n , 14 , 32.5 , 13.80145
n , 15 , 35 , 14.8708
n , 16 , 37.5 , 15.94125
n , 17 , 40 , 17.0128
n , 18 , 42.5 , 18.08545
n , 19 , 45 , 19.1592
n , 20 , 47.5 , 20.23405
n , 21 , 50 , 21.31
n , 22 , 52.5 , 22.38705
n , 23 , 55 , 23.4652
n , 24 , 57.5 , 24.54445
n , 25 , 60 , 25.6248
n , 26 , 62.5 , 26.70625
n , 27 , 65 , 27.7888
n , 28 , 67.5 , 28.87245
n , 29 , 70 , 29.9572
n , 30 , 72.5 , 31.04305
n , 31 , 75 , 32.13
n , 32 , 77.5 , 33.21805
n , 33 , 80 , 34.3072
n , 34 , 82.5 , 35.39745
n , 35 , 85 , 36.4888
n , 36 , 87.5 , 37.58125
n , 37 , 90 , 38.6748
n , 38 , 92.5 , 39.76945
n , 39 , 95 , 40.8652
n , 40 , 97.5 , 41.96205
n , 41 , 100 , 43.06
n , 42 , 102.5 , 44.15905
n , 43 , 105 , 45.2592
n , 44 , 107.5 , 46.36045
n , 45 , 110 , 47.4628
n , 46 , 112.5 , 48.56625
n , 47 , 115 , 49.6708
n , 48 , 117.5 , 50.77645
n , 49 , 120 , 51.8832
n , 50 , 122.5 , 52.99105
n , 51 , 125 , 54.1
n , 52 , 127.5 , 55.21005
n , 53 , 130 , 56.3212
n , 54 , 132.5 , 57.43345
n , 55 , 135 , 58.5468
n , 56 , 137.5 , 59.66125
n , 57 , 140 , 60.7768
n , 58 , 142.5 , 61.89345
n , 59 , 145 , 63.0112
n , 60 , 147.5 , 64.13005
n , 61 , 150 , 65.25
n , 62 , 152.5 , 66.37105
n , 63 , 155 , 67.4932
n , 64 , 157.5 , 68.61645
n , 65 , 160 , 69.7408
n , 66 , 162.5 , 70.86625
n , 67 , 165 , 71.9928
n , 68 , 167.5 , 73.12045
n , 69 , 170 , 74.2492
n , 70 , 172.5 , 75.37905
n , 71 , 175 , 76.51
n , 72 , 177.5 , 77.64205
n , 73 , 180 , 78.7752
n , 74 , 182.5 , 79.90945
n , 75 , 185 , 81.0448
n , 76 , 187.5 , 82.18125
n , 77 , 190 , 83.3188
n , 78 , 192.5 , 84.45745
n , 79 , 195 , 85.5972
n , 80 , 197.5 , 86.73805
n , 81 , 200 , 87.88
n , 82 , 202.5 , 89.02305
n , 83 , 205 , 90.1672
n , 84 , 207.5 , 91.31245
n , 85 , 210 , 92.4588
n , 86 , 212.5 , 93.60625
n , 87 , 215 , 94.7548
n , 88 , 217.5 , 95.90445
n , 89 , 220 , 97.0552
n , 90 , 222.5 , 98.20705
n , 91 , 225 , 99.36
n , 92 , 227.5 , 100.51405
n , 93 , 230 , 101.6692
n , 94 , 232.5 , 102.82545
n , 95 , 235 , 103.9828
n , 96 , 237.5 , 105.14125
n , 97 , 240 , 106.3008
n , 98 , 242.5 , 107.46145
n , 99 , 245 , 108.6232
n , 100 , 247.5 , 109.78605
n , 101 , 250 , 110.95
n , 102 , 9.163 , -0.579
!定义材料属性
et,1,link10,,2
mp,dens,1,4849.526
mp,ex,1,2e11
!生成单元
r,1,0.01517,0.001648
r,2,0,19111
type,1
mat,1
real,1
*do,k,1,100,1
e,k,k+1
*enddo
sstif,on
!施加约束
d,1,all
d,101,all
/solu
acel,,9.81
solve
finish
/solu
antype,modal
modopt,lanb,10,0.2,10
d,1,all
d,101,all
pstres,on
mxpand,10
solve
finish
/solu
antype,trans
trnopt,full
d,1,all
d,101,all
alphad,0.014
betad,0.000092
sstif,on
autots,on
nsubst,1 !每一荷载步的子步数
kbc,0
*do,i,1,2000,1
*if,i,le,1200,then
time,0.05*i
f,7,fy,-1800*sin(6.283*0.05*i)
*else
time,0.05*i
f,7,fy,-1800*sin(0*0.05*i)
*endif
solve
!lswrite,i
*enddo
outres,all,all
finish
/post26
solu,
nsol,2,4,u,y
nsol,3,8,u,y
/grid,1
/axlab,y,amplitude(m)
plvar,2,3
prcplx,1
prvar,2,3
finish
|
