Bai A. Spectra and properties of normal waves in an anisotropic piezoelectric crystal layer of orthorhombic and trigonal system

The aim of this thesis is the development and application of refined theoretical methods concerning determination of the main dispersion, kinematic, energy and asymptotic properties of normal waves in three-dimensional electroelastic plate waveguide. The waveguide's material is piezoelectric of low anisotropy level, specifically various cuts of piezocrystal of orthorhombic and trigonal system. Proposed methods is based on a combination of a parametric analysis of roots of characteristic polynomials of dynamic electro-elasticity equa-tions in absence of root's explicit analytic form, as well as direct numerical study of transcendental dispersion equations constructed in analytical form. By applying the method full dispersion spectra of homogeneous and heterogeneous electroelastic normal waves were calculated and investigated for cases of AT-, BT-, NT-, GT-cuts of ?-quartz as well as for Z-cut of Rochelle salt. By using the symmetric polynomials theory dispersion equation for phase velocities of electroelastic surface waves in piezocrystal half-space of orthorhombic system has been obtained in polynomial form. Patterns in processes of high short asymptotic transformation of studied wave types to localized electroelastic waves for different directions of propagation have been identified and generalized.