Propagation characteristics of Lamb waves in a bilayer plate comprised of a PMN-PT single crystal layer and an elastic layer were investigated in this study. The profiles of the bilayer plate's upper and lower surfaces and the common interface between the PMN-PT and elastic layers were assumed to be periodic corrugation instead of perfect planes. The PMN-PT single crystal was poled along the [0 1 1]c direction with macroscopic symmetry of orthonormal mm2. The dispersion relations of Lamb waves for electrically open and electrically short boundary conditions were derived in the closed form. The effects of the related corrugation parameters and thickness ratios of the PMN-PT single crystal layer to the elastic layer on the phase velocity were assessed using the numerical results. The parameters of the amplitudes and wavenumbers related to the periodic corrugation played key roles in the propagation and dispersion behaviors of the Lamb waves. The phase velocity increased, especially in a lower wavenumber range when the upper or lower surfaces were considered corrugated contours. However, the phase velocity decreased when the common interface was treated as a corrugated configuration. The smaller thickness ratio produced higher phase velocity. These results can provide some fundamental characteristics for the design and application of acoustic wave devices fabricated with PMN-PT single crystals, especially for improving the efficiency and sensitivity.
Keywords: Bilayer plate; Dispersion relation; Lamb wave; PMN-PT single crystal; Periodic corrugation.
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