基于弯折频率变换的Lamb波高分辨率损伤成像

Lamb波在结构健康监测中受到广泛关注，但其在传播过程中存在着多模和频散特性，不利于损伤定位和高分辨率成像。弯折频率变换（Warped Frequency Transform, WFT）通过构建合理的弯折映射可实现对频率轴的弯折。基于Lamb波群速度频散曲线设计弯折频率变换，则可用于Lamb波信号的处理。本文从直接补偿角度出发，利用WFT对传感信号进行频散抑制。提出了基于WFT的高分辨率损伤成像方法，利用有限元软件ABAQUS进行了带损伤铝板中Lamb波传播的仿真。仿真结果表明WFT能有效压缩频散的波包，通过本文所提成像方法可实现高分辨率损伤成像。

High-resolution Damage Imaging of Lamb Waves Based on Warped Frequency Transform

Lamb waves received great attention in structural health monitoring (SHM), but it is complicated by the multi-mode character and the dispersion effect, which impacts the damage positioning and high-resolution imaging. Warped frequency transform(WFT) can warp the frequency axis by setting up a reasonable warped map. Warped frequency transform based on the group velocity dispersion curves of Lamb waves can be employed to process Lamb waves. Based on this direct dispersion compensation idea, WFT is adopted here to process the measured signals to suppress dispersion. A new method of high-resolution damage imaging is proposed based on WFT, and the propagation of Lamb waves in damaged aluminum pate is simulated by finite element software ABAQUS. Results show that WFT can effectively compress dispersed wave-packets, and high-resolution damage imaging can be obtained by the proposed method.