Wavelet analysis on shock response of a real ship subjected to non-contact underwater explosion
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摘要: 为了研究水下爆炸条件下船体冲击振动响应时频特征,针对某实船非接触水下爆炸实验冲击响应测试实验数据,基于小波分析及能量统计方法对响应信号进行时频特性分析,得到了实船非接触水下爆炸冲击振动响应的时频分布和能量分布。分析结果表明,采用基于小波变换的时频分析方法,可以成功获得船体冲击响应信号不同频率段下的强度、能量和作用时间等时频细节信息,包括响应信号各频段冲击峰值、衰减过程、振动能量及其在全频率段上所占的分数。通过对小波频段能量统计以及冲击强度分析发现,冲击响应能量频段分布较广,主甲板及以下甲板全频段振动能量的80%以上在312.5 Hz以上,上层建筑甲板平台各频段冲击振动能量分数向低频段转移。Abstract: With a view to obtaining the characterisstic of shock response of the hull to underwater explosion, based on the experimental impact vibration data subjected to underwater explosion trial of ship, the time-frequency characteristics of the monitored impact vibration signals were studied by wavelet analysis. By using these signals, the acceleration-time curves and the energy distributions in different blasting frequency bands were obtained. The result show that the time-frequency characteristics of impact vibration can be obtained by the wavelet analysis, it is easy to get the time-frequency information details of the impact vibration signal intensity, frequency and duration, including the peak values and attenuation and vibration energy of impact vibration signals. Based on the analysis of the energy statistics and impact strength of the wavelet frequency band, found that has a wide distribution of shock response spectrum energy, more than 80% of vibration energy distributed above 312.5Hz at the main deck and below deck, and more vibration energy in low frequency at superstructure deck platform.
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表 1 小波分解频段
Table 1. Corresponding frequency bands of wavelet decomposition
小波系数 d1 d2 d3 d4 d5 d6 d7 d8 d9 a9 fi/Hz 5 000~10 000 2 500~5 000 1 250~2 500 625~1 250 312.5~625 156.25~312.5 78.125~156.25 39.062 5~78.125 19.531 25~39.062 5 0~19.531 25 表 2 各甲板测点冲击响应信号小波分解信号各频带能量信息
Table 2. Band parameters for shock response signals of decks
i fi/Hz Ai, max/g Ei/g2 ki/% 甲板01 甲板1 甲板2 甲板01 甲板1 甲板2 甲板01 甲板1 甲板2 d1 5 000~10 000 11.51 33.36 111.36 7 307.46 53 917.82 518 888.60 3.02 3.14 11.28 d2 2 500~5 000 8.70 50.27 95.15 7 600.98 115 947.60 384 515.90 3.14 6.76 8.36 d3 1 250~2 500 15.43 40.09 107.17 22 028.13 85 816.75 260 952.60 9.10 5.01 5.67 d4 625~1 250 31.28 107.97 132.08 46 007.65 397 562.20 668 500.30 19.01 23.20 14.50 d5 312.5~625 12.98 126.22 184.77 42 606.12 791 057.50 2 184 242.00 17.61 46.20 47.50 d6 156.25~312.5 7.67 27.83 41.02 10 172.70 112 680.40 291 414.80 4.20 6.58 6.33 d7 78.125~156.25 2.85 9.75 13.79 3 641.01 43 371.17 111 032.10 1.50 2.53 2.41 d8 39.062 5~78.125 8.09 7.82 9.74 26 572.24 31 322.22 107 088.90 10.98 1.83 2.33 d9 19.531 25~39.062 5 5.98 4.33 5.23 37842.86 40 194.21 46 575.54 15.64 2.35 0.58 a9 0~19.531 25 8.20 7.48 8.73 38 223.99 41357.92 48 494.98 15.80 2.41 1.00 -
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