Piezoelectric Love Waves in an FGPM Layered Structure.

An analytical approach is used to investigate the existence and propagation behavior of surface electro-elastic Love waves in an ideally layered structure consisting of a functionally graded piezoelectric substrate and a dielectric layer. The piezoelectric substrate is polarized in the direction perpendicular to the wave propagation plane and its material parameters change continuously along the thickness direction. The dispersion equations for the existence of surface Love waves with respect to phase velocity are obtained for electrically open and shorted cases, respectively. A detailed investigation of the effects of material gradient on dispersion curve, phase velocity, group velocity, and electromechanical coupling factor is carried out. Numerical results show that material gradient significantly affects the fundamental mode of Love waves but has only negligible effects on the high order modes. Large electromechanical coupling factors could be achieved by an appropriate adjustment of gradient coefficients, which is of practical interest for designing acoustic wave devices. [ABSTRACT FROM AUTHOR]