Inspection of simulated weld penetration depth using laser-generated Lamb waves and wavelet signal processing

The Laser/EMAT ultrasonic (LEU) technique has raised interest in weld quality inspections because of its non-contact feature. However, the application of the technique in thin structures is challenging because of the difficulties in signal interpretations. In this work, a Continuous Wavelet Transform (CWT)-based algorithm is developed to calculate the transmission coefficients of laser generated Lamb waves. The transmission coefficients calculated using this method are shown to be able to predict the simulated weld penetration depths in thin structures.