Study on Wave Propagation Phenomena in Layered Media

Abstract

The wave propagation includes the situation where waves originate and propagate in the medium with different material properties and geometry. Studying the sur face wave propagation in the layered structure has been of interest to researchers due to their extensive applications in the fields of geophysics, composite materials, acoustics as well as in nondestructive evaluation. The interactions among these layers depend on many factors such as mechanical properties, loading conditions, interfacial conditions, etc. Traditionally, the layered model involves a substrate based on the classical elastic model but this theory ignore the microstructure-related scale effects. To capture the size effects, two size-dependent models, i.e., Micropolar elastic model and Couple stress elastic model have been considered along with other different ma terial layers such as smart material (piezoelectric material), viscoelastic material, orthotropic material, self-fiber reinforced material. The whole work of the thesis is structured into six chapters which are summarized as follow: Chapter-1 This chapter involves the basic overview on continuum mechanics, classical theory of elasticity with brief summary on generalized Hooke s law. This chapter also in volves the emergence of different microcontinuum theories, i.e., Micropolar theory and Couple stress theory of elasticity, basic governing equations together with consti tutive equations are summarized. This also includes the brief overview on anisotropic materials like piezoelectric materials (also called Smart Materials ) and viscoelastic materials. Chapter-2 In this chapter, the propagation of Love wave have been investigated in a piezoelectric xi xii ceramic bonded over a couple stress elastic half-space. The substrate is considered to have properties of a microstructure like granular macromorphic rock (Dionysos Mar ble). This study has been carried out by using two sets of piezoelectric medium, i.e., P ZT and#8722;5H and BaT iO3.