Research on Fatigue Crack Monitoring by Active Lamb Wave Based on HHT
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摘要: 由于兰姆波具有频散效应,使得其信号形式较为复杂、分析困难,这就为损伤监测中的模式波包提取带来了很大的难度。利用希尔伯特-黄变换(Hilbert-Huang Transform,HHT)对信号包络进行提取,可以达到简化原始信号、提高损伤监测精度和效率的目的。与利用短时傅里叶变换(Short Time Fourier Transform,STFT)提取信号包络的方法相比,希尔伯特-黄变换的自适应性更强、效率更高,更适合兰姆波分析。通过对铝制薄板中的裂纹扩展监测试验表明,结合了希尔伯特-黄变换的损伤指数法,对兰姆波信号的模式提取更为准确、对裂纹的扩展也更为敏感。Abstract: The dispersion in Lamb wave complicates the signal shape and analysis procedure and this phenomena also bring difficulties in mode packet extraction during damage monitoring. Extraction the wave packet via Hilbert-Huang Transform(HHT)can simplify the raw signal and improve precision and efficiency of damage monitoring. Compared with Short Time Fourier Transform(STFT), the HHT is more suitable for Lamb wave analysis with higher self-adaptivity and efficiency. The experiment of crack expansion monitoring on aluminum plate showed that the damage index combined with HHT can extract the lamb wave packet with higher accuracy and higher sensitivity to the crack expansion than those obtained by STFT appraoch.
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Key words:
- damage monitoring /
- design of experiments /
- efficiency /
- experiments
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