| A unified analytical treatment supported by extensive numerical illustrations of the ultrasonic acoustic wave propagation in multilayered anisotropic media with piezoelectric interaction is presented. The media are allowed to possess as low as monoclinic anisotropic symmetry and associated piezoelectric coupling and are also assumed to be immersed in water and subjected to incident acoustic beams at arbitrary polar and azimuthal angles. Various types of ultrasonic acoustic waves, such as bulk waves in infinite media, Rayleigh and Bleustein-Gulyaev surface waves in substrates, Lamb and Love waves in plates, and relative waves of these in multilayered media are studied in this research, respectively. 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 multilayered piezoelectric media. This equation can be written in simple and completely separate terms pertaining to symmetric and antisymmetric modes for a single plate. It is found that piezoelectric coupling, as well as water, influence the modes of waves. Higher symmetry, such as orthotropic, transverse isotropic and cubic, are contained implicitly in our analysis. We also demonstrate that the motion of the sagittal (Lamb) and SH modes uncouple for propagation along axes of symmetry. For such cases, however, piezoelectric coupling can influence one of these types of modes depending upon the type of piezoelectric model adopted. Due to the different boundary conditions, electric shorted or free, on the surfaces of the media, a electromechanical coupling constant is calculated, from the fraction change of the phase velocity of these two cases, to show the degree of piezoelectric coupling for various materials or for different combinations of lamination of layered media by various materials. |
