基于EMD的激光声表面波仿真分析

Simulation analysis of laser surface acoustic wave based on EMD

激光超声凭借其具有非接触、信号的信噪比高、灵敏度高、频带宽等特点,在材料的检测方面有着独特优势。本文利用有限元软件针对激光激励声表面波过程进行了数值模拟,得到了声表面波的传播特性;对实际检测信号进行了EMD去噪,得到了去噪后的重构信号,将去噪后的信号同仿真信号对比。结果证明激光超声激发的声表面波主要沿着材料表层向四周发散,其在远场区域会有小幅度的衰减,并且经过EMD去噪后的信号具有和仿真信号相同的特征,对今后激光超声的实验具有重要的参考价值。

Laser ultrasound has unique advantages in material detection due to its non-contact characteristics,high signal-to-noise ratio,high sensitivity,and frequency bandwidth.This paper uses finite element software to numerically simulate the laserexcited surface acoustic wave process,and obtain the propagation characteristics of the surface acoustic wave;for the actual detection signal,the EMD denoising is carried out,and the reconstructed signal after denoising is obtained.The latter signal is compared with the simulated signal.The result proves that the surface acoustic wave excited by laser ultrasound mainly diverges around the surface of the material,and it will have a small amplitude attenuation in the far field area.It is demonstrated that the signal after EMD denoising has the same characteristics as the simulation signal.The experiments of laser ultrasound will have important reference value in the future.