Computer Simulation for Time Signal of Symmetrical Mode Lamb Wave

The signal processing of Lamb wave is complex because of its multi-mode and frequency-dispersion characteristics. A method to analyze symmetrical single-mode ultrasonic Lamb wave in the time domain is presented. Based on the analysis of frequency-dispersion characteristic of symmetrical mode Lamb wave, we deduced the half analytic expression of its time signal, and implemented simulation computation to the time signal of the zero-order symmetrical mode Lamb wave which had propagated in the aluminum lamina for a distance. The change of waveform with the propagation distance in different frequency bands is analyzed. The simulation result indicated the method could effectively compute the time waveform of single-mode Lamb wave. The method could offer the theoretical foundation for the application of symmetrical Lamb wave measuring technique in the time domain.