Constraint-induced crack initiation at electrode edges in piezoelectric ceramics

A strain incompatibility arises between the electrically active and inactiv e parts of a partially electroded piezoelectric material. This leads to cra cking perpendicular to the electrode edge. Symmetric partial electrodes of different widths were applied to lead zirconate titanate (PZT) plates to st udy the development of these cracks. Different cracking patterns appeared u pon application of an electric field, depending on the degree of coverage a nd on the thickness of the plates. The apparent coercive fields are correla ted to the degree of clamping and the amount of cracking in the specimens. Non-linear finite element modelling is used to analyse the material respons e. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rig hts reserved.