SH waves in functional gradient piezoelectric material layer

An exact analysis approach based on the transfer matrix method is used to investigate SH waves in functionally gradient piezoelectric material (FGPM) layer bonded to a semi-infinite homogeneous piezoelectric substrate. The material properties change gradually through the thickness of the layer. The transfer matrix considering initial stress is derived. Numerical examples indicate that appropriate gradient distributing of the material properties make SH waves to propagate along the surface of layer, which is in favor of acquiring a better performance of the SAW devices and a less penetration of depth of waves. The initial compressive stress in the direction of propagation of SH waves diminishes the phase velocity and increases the electromechanical coupling factor.