Fracture analysis of piezoelectric materials with an arbitrarily oriented crack using energy density theory

The fracture behavior of an arbitrarily oriented crack in a piezoelectric medium is studied in this paper by using the energy density theory. The governing parameters used in the fracture analysis are the remote mechanical load σ∞, remote electric field E∞, and the polarization orientation η with respect to the crack plane. The solution for the energy density factor S is modified to include the stress intensity factors KI and KII, the electric displacement intensity factor KD (or the electric field intensity factor KE) and the polarization orientation η. This paper's theoretical results discuss the importance of the polarization orientation on the crack driving force Smin and the crack propagating angle θ0. For an arbitrarily oriented crack, a negative electric field was found to impede crack growth whereas a positive electric field enhanced it. The driving force and the crack propagation angle were also found to significantly influence polarization η. The ratio R (=E∞/σ∞) was used as a parameter to judge the significance of mechanical load or electric field. The inadequacy of using the energy release rate in predicting the fracture behavior is also discussed.