Toughening due to domain switching in single crystal ferroelectric materials

In this paper Mode I steady state crack growth in single crystal ferroelectric materials is investigated. Specifically, the fracture toughness enhancement due to domain switching near a steadily growing crack tip is analyzed. For this purpose, an incremental phenomenological constitutive law for single crystal ferroelectric materials is implemented within a finite element model to calculate thestressandremanentstrainfieldsaroundthecrack tip. Also, the ratio of the far field applied energy release rate tothe crack tip energy release rate, i.e. the toughening, is calculated. The numerical computations are carried out for single crystal ferroelectric materials of tetragonal or rhombohedral structure with different switching hardening and irreversible remanent strain levels. Toughening levels for crack growth along different crystallographic directions andplanesareobtainedandcompared.Resultsfrom numerical computations for the toughening anisotropy for both tetragonal and rhombohedral crystals are presented and discussed.