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The transition regime between bulk waves and Lamb waves: an analytical analysis

In this letter, the transition regime between bulk waves and Lamb waves, which is generated at large frequency-thickness (fd) products, is studied. Unlike Lamb waves and bulk waves, the transition regime appears as a train of nearly non-dispersive pulses with a constant time interval between each other. Based on Rayleigh–Lamb equation, the approximate analytical solution of this pulse train under a simple assumption is given, and it explains the transition process from Lamb waves to bulk waves. Finally, the great potential of the transition regime in non-destructive testing is discussed.