Influence of electric fields on the fracture of ferroelectric ceramics

This paper deals with the fracture mechanics of piezoelectric solids. All investigations consider a single crack, which is exposed to combined electrical and mechanical loading. The main subject of interest is the influence of electric fields on the fracture toughness of ferroelectric ceramics and the derivation of an appropriate fracture criterion. Numerical techniques are presented, allowing for the calculation of fracture quantities, i.e. stress intensity factors and energy release rates, once the piezoelectric field problem has been solved for arbitrary crack configurations using the finite element method. In order to describe a possible shielding of the crack tip due to ferroelectric/elastic domain switching events, a micromechanical model has been developed, based on a closed form solution of the piezoelectric field problem. In order to verify the theory, fracture experiments on barium titanate DCB specimens have been evaluated and compared to predictions of the model. (C) 2002 Elsevier Science Ltd. All rights reserved.