Pattern Recognition of Laser-generated Lamb Wave Based on Time-frequency Analysis

The modes of laser-generated Lamb waves are able to be recognized by different kinds of spectrum analytical methods such as fast fourier transform (FFT), short time fourier transform (STFT) and Hilbert-Huang transform (HHT). It can be found that by FFT and STFT, only the powerful mode can be recognized, however, by HHT, both of powerful and weak modes can be recognized. The study provides basic research for laser ultrasonic detection.