Multiple Moving Cracks in an Orthotropic Strip Sandwiched between Two Piezoelectric Layers

Dynamic fracture mechanics of layered materials has been gaining lots of attentions among the researchers where the layered materials are extensively used in various products and devices to improve structural performance such as strength and durability. The influence of the crack moving speed on the the stress intensity factors was a popular subject in classical elastodynamics. Among the models of propagating crack, Yoffe crack is the simplest and the most classical one. In this model, a Griffith crack is assumed to propagate straight at a constant speed with its length unchanged. Most of the piezoelectric sensors are layered structures, and the control of laminated structures including piezoelectric devices has been extensively studied in the literature. In a practical application, bonding of piezoelectric layers frequently happens. The simplest structure is just composed of two piezoelectric layers and a substrate; therefore, the study of the fracture mechanics of the materials composed of piezoelectric layers is very substantial in the design of piezoelectric devices. Orthotropic composites are sometimes used as the substrate of layered piezoelectric devices to enhance mechanical performance. Sih et al. [1] studied the dynamic behavior of a moving crack in layered composites.