Warped frequency transform for damage detection using Lamb waves
Warped frequency transform for damage detection using Lamb waves
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DOI：
10.1117/12.847688
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发表时间：
2010-03
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通讯作者：
L. De Marchi;M. Ruzzene;Buli Xu;E. Baravelli;A. Marzani;N. Speciale
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作者：
L. De Marchi;M. Ruzzene;Buli Xu;E. Baravelli;A. Marzani;N. Speciale
本文提出了一种新的时频分析方法，用于结构健康监测中的导波传播分析。该方法将扭曲频率变换（WFT）与基追踪算法相结合，即使在与波导宽带激励相关的多模态色散传播情况下，也能生成稀疏而准确的采集信号时频表示。这是通过由优化的原子组成的超完整字典来获得的，这些字典设计用于匹配各种传播模式的光谱-时间结构。对采集到的几种波形进行扭曲基追踪（W-BP）分解，得到的距离信号可以通过经典的波束形成技术进行组合，用于成像目的。该方法通过在1 mm厚铝板上人工引入裂纹进行宽带GW激励获得的实验数据进行了验证，然后通过扫描激光多普勒振动仪记录多波导位移。色散补偿和高分辨率源以及缺陷成像即使在不能直接测量的域区域也得到了证明。
A novel time-frequency procedure is presented in this paper for guided wave (GW) propagation analysis in structure health monitoring (SHM) applications.The proposed approach combines the Warped Frequency Transform (WFT) with a Basis Pursuit algorithm to generate a sparse yet accurate time-frequency representation of the acquired signals even in the case of multi-modal dispersive propagation associated to broadband excitation of the waveguide. This is obtained through over complete dictionaries composed by optimized atoms which are designed to match the spectro-temporal structure of the various propagating modes.The Warped Basis Pursuit (W-BP) decomposition of several acquired waveforms results in distance signals that can be combined through classical beamforming techniques for imaging purposes. This approach is tested on experimental data obtained by broadband GW excitation in a 1 mm thick aluminum plate with an artificially introduced through crack, followed by multiple waveguide displacement recording through a scanning laser Doppler vibrometer. Dispersion compensation and high-resolution source as well as defect imaging is demonstrated even in domain regions that are not directly accessible for measurement.