Automated methodology to locate notches with Lamb waves

This study develops an automated method capable of detecting notches in isotropic plates. Laser ultrasonic techniques are used to generate and detect Lamb waves in perfect and notched plates. These signals are first transformed into the time-frequency domain using a short time Fourier transform (STFT) and subsequently into the group velocity-frequency domain. Finally, the notch is located with an autocorrelation in the group velocity-frequency domain. A verification of the proposed methodology shows excellent agreement with the actual location of the notch. c 2001 Acoustical Society of America PACS number: 43.20.Mv, 43.35.Cg Date Received: April 19, 2001 Date Accepted: May 20, 2001