Publisher Summary Piezoelectric ceramics can sense and actuate by rapidly converting mechanical and thermal signals into electrical ones, the reverse also being true. The piezoelectric properties and quick response characteristics have made piezoelectric ceramics one of the most commonly used smart materials. The intrinsic brittleness of piezoelectric ceramics and damageability of the materials under electric field — making the materials prone to fracture — are of major concern for product reliability. The fracture of piezoelectric ceramics under combined electrical and mechanical loading has been among the most prevalent research topics. The chapter describes piezoelectricity, ferroelectrics, spontaneous polarization, and electric domains; and discusses the poling process, the hysteresis loop of polarization versus the electric field strength, and the butterfly loop of strain versus the electric field. The chapter focuses on the basic equations commonly used in the study of the fracture behavior of piezoelectric ceramics within the thermodynamics framework, the general solution based on Stroh's formalism (a powerful tool for solving two-dimensional electroelastic problems), analysis of Green's functions for insulating elliptical cavities and cracks, study of conductive elliptical cavities and cracks, study of piezoelectric interface cracks, and three-dimensional electroelastic problems. The four types of nonlinear approaches considered are: electrostriction, domain switching, domain wall kinetics, and polarization saturation at a crack tip. The polarization saturation model that treats piezoelectric ceramics as mechanically brittle and electrically ductile materials is also discussed. The chapter provides an overview of experimental observations whose results show that microstructure and temperature have a profound influence on the fracture behaviors of piezoelectric ceramics under purely mechanical loads, and also discusses the commonly used failure criteria, the electric saturation model, the stress intensity factor criterion and the stress criterion.

Fracture of piezoelectric ceramics

Cai-Fu Qian

Papers

Linear electro-elastic analysis of a cavity or a crack in a piezoelectric material