Propagation Characteristics Of SH Waves In Orthorhombic Piezoelectric Layered Structures With An Imperfect Interface

Due to being able to convert mechanical energy into electric energy and vice versa, piezoelectric materials have been widely used in technology such as sensors, delay lines, filters and resonators, and so on. These applications are closely related to elastic wave propagation. Therefore, elastic waves propagating in piezoelectric materials and structures have been an active topic.This dissertation deals with the propagation of shear horizontal waves in an orthorhombic piezoelectric layered structures with an imperfect interface, where the piezoelectric crystals are cut around one of the material principle axes. The considered layered structures include two configurations: one being the elastic layer on the piezoelectric half-space and the other being the piezoelectric layer on the elastic half-space. The solutions of SH waves and the dispersion equations are first derived. Then the phase velocities are calculated to show the effects of interface imperfection cut orientations and structure forms on the dispersion characteristics of SH waves.The obtained results include that: 1) For the elastic layer/piezoelectric half-space structure, the phase velocity of the first mode starts from the B-G wave speed of the piezoelectric material, whereas the phase velocities of the higher modes begin at the limit speed of the piezoelectric material. When the wave number is smaller, the cut angle has obvious effect on the phase velocity of the first mode. 2) For the piezoelectric layer/elastic half-space structure, when the surface of the piezoelectric layer is electrically shored, the phase velocity of the first mode tends towards the B-G wave speed of the piezoelectric layer, whiles the phase velocities of the higher modes approach the limit speed of the piezoelectric layer. For the electrically open condition, the asymptotic value of the phase velocity is the limit speed of the piezoelectric layer. 3) The existence of imperfect interface reduces the propagation velocities of SH waves. The imperfect interface can make the phase velocity less than the B-G wave for the electrically shorted case. This characteristic does not appear when the piezoelectric layer is subjected to the electrically open condition.