Numerical investigations of Lamb waves excited by interdigital transducers and incident on piezoelectric plates

Abstract

This study investigated the thickness mode and thickness shear mode of Lamb waves excited by a surface interdigital transducer and incident on piezoelectric ceramic plates. We numerically calculated the time-domain response, frequency-domain response, and propagation characteristics of these waves. To determine the electric field intensity of a surface interdigital transducer with a semi-infinite domain, the driving potentials of the surface electrodes of the piezoelectric plates were approximated using a series solution and the Legendre function. The wave propagation responses of the plates were determined by considering the electromechanical coupling effect of piezoelectric materials and assuming the electrical boundary conditions of three external excitation sources. A modified Clenshaw–Curtis numerical integration method was used to calculate the frequency-domain response of the Lamb wave displacement of the piezoelectric plates excited by an interdigital electrode. The time-domain response of this displacement was determined using the inverse fast Fourier transform method. This study also examined the near- and far-field Lamb wave responses of interdigital transducers with different electrode numbers and electrode widths.