Rayleigh wave on the half-space with a gradient piezoelectric layer and imperfect interface

In this study, we consider the propagation of a Rayleigh wave on an anisotropic half-space with a piezoelectric gradient covering layer and imperfect interface. First, the state transfer equation is derived from the governing equations and constitutive relations. The transfer matrix of the state vector is then obtained by solving the state transfer equation and the stiffness matrix is obtained. The total surface stiffness matrix is obtained by combining the transfer matrices and the stiffness matrices of the piezoelectric half-space, the gradient covering layer, and the imperfect interface. Finally, the application of the electrically open circuit, short circuit conditions, and mechanically traction-free conditions gives the frequency dispersive relation. We investigate five types of gradient profiles for the covering layer where the material parameters vary gradually from the top to the bottom, and two types of imperfect interfaces, i.e., dielectrically weakly and highly conducting but mechanically compliant interfaces. The numerical results show that the surface wave speed is sensitive to the gradient profile of the covering layer with the mechanically and dielectrically imperfect interfaces between the covering layer and the substrate.