Influence of polarization and the coating properties on propagation of Sh-waves in piezoelectric structures

We have considered a problem on the propagation of shear horizontally polarized surface waves in the framework of a piezoelectric structure with an inhomogeneous coating from a functionally graded material. We assume that physical properties of the coating change in a piecewise continuous way. As a base material of the structure, we use a piezoelectric of hexagonal syngony with a 6mm class symmetry. The solution of the problem is formulated in Fourier transforms on the basis of a modified approach which combines analytical and numerical methods to obtain the solution for homogeneous and inhomogeneous components of the structure. On the basis of the dispersion equation analysis, we have investigated the influence of the direction of a polarization vector and of the type of the coating inhomogeneity on the peculiarities of surface acoustic waves (SAW) propagation and on the behaviour of the coefficient of the electromechanical coupling in an "acoustically homogeneous" structure.