基于横波检测的激光超声底部缺陷成像方法

Bottom defect imaging method of laser ultrasonic based on shear wave detection

针对超声衍射横波检测方法存在检测精度差、信号信噪比低以及底部缺陷检测不适用的问题,针对底部缺陷提出了一种激光超声反射横波的合成孔径聚焦成像新方法。首先建立了金属底部缺陷的二维瞬态激光超声力-固耦合模型,分析了激光超声激励下的底部缺陷的声波传播特性。然后搭建了激光超声检测平台,对10mm厚铝板底部缺陷进行合成孔径聚焦成像,仿真与实验成像结果表明,新方法能反映出底部缺陷的宽度,与实际宽度误差在5%以内。

Aiming at the problems of poor detection accuracy,low signal-to-noise ratio and inapplicability of bottom defect detection in ultrasonic diffraction shear wave detection method,a new synthetic aperture focusing imaging method of laser ultrasonic reflected shear wave is proposed.Firstly,the two-dimensional transient laser ultrasonic force-solid coupling model is established for the metal bottom defect,and the acoustic wave propagation characteristics affected by the bottom defect excited by laser ultrasonic are analyzed.Then the laser ultrasonic detection platform is built to carry out synthetic aperture focusing imaging at the bottom of 10mm thick aluminum plate.The simulation and experimental results show that the synthetic aperture focusing imaging algorithm based on reflected shear wave can reflect the width of bottom defects,and the error with the actual width is less than 5%.