The influence of piezoelectricity on free and reflected waves from fluid-loaded anisotropic plates

Abstract

A unified analytical treatment is presented supported by extensive numerical illustrations of the interactions of ultrasonic waves with piezoelectric anisotropic plates. The plates are allowed to possess up to monoclinic anisotropic symmetry and associated piezoelectric coupling. The plates are also assumed to be immersed in water and subjected to incident acoustic beams at arbitrary polar and azimuthal angles. Simple analytical expressions for the reflection and transmission coefficients are derived, from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the piezoelectric plates. This equation is written in simple and completely separate terms pertaining to symmetric and antisymmetric modes. It is found that piezoelectric coupling, as well as water, influence both types of modes. Higher symmetry, such as orthotropic, transverse isotropic, and cubic, are contained implicitly in this analysis. It is also demonstrated that the motion of the sagittal (Lamb) and SH modes uncouple for propagation along axis of symmetry. For such cases, however, piezoelectric coupling can influence one of these types of modes depending upon the type of piezoelectric model adopted.