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

摘要

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 K_Ⅰ and K_Ⅱ, the electric displacement intensity factor K_D (or the electric field intensity factor K_E) and the polarization orientation η. This paper's theoretical results discuss the importance of the polarization orientation on the crack driving force S_(min) and the crack propagating angle θ_0. 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.