Heterogeneity Influence on Electric Field Induced Piezoelectric Microfracture

摘要

Spatial variations in piezoelectric material properties can influence localized residual stresses under electro-mechanical loading, which has been shown to contribute to microfractures (Jiang, Q., Subbarao, E.C. and Cross, L.E. 1994. "Grain Size Dependence of Electric Fatigue Behavior of Hot Pressed PLZT Ferroelectric Ceramics," Acta Me tall. Mater., 42(ll):3687-3694; Lynch, C.S. 1998. "Fracture of Ferroelectric and Relaxor Electro-ceramics: Influences of Electric Field," Acta Mater., 46(2):599-608; Wang, Z., Jiang, Q., White, G.S. and Richardson, A.K. 1998. "Processing Flaws in PZT Transducer Rings," Smart Mater. Struct., 7:867-873). The effect of residual stress on piezoelectric microfracture has been modeled by introducing a crack at the edge of a piezoelectric elliptic inclusion with dissimilar piezoelectric matrix material properties. Piezoelectric weight functions were used to assess changes in intensity factors and energy release rates when an inclusion is present. The shape of the elliptic inclusion is shown to have an effect on local driving forces. Additionally, comparison of impermeable and permeable crack face boundary conditions illustrate the importance of applying the more 'physical' permeable conditions to achieve positive flaw-localized driving forces under electrical loading.