Crack initiation and crack propagation in partially electroded PZT

For partially electroded piezoelectric materials, a strain incompatibility arises between the electrically active part and the electrically inactive part of the material. This can lead to crack initiation and crack propagation perpendicular to the electrode edge. In order to study crack initiation, a symmetrical geometry with the electrodes in the centre of the surfaces of thin lead zirconate titanate (PZT) plates was devised. Upon application of the electrical field, different cracking patterns appear, depending on degree of coverage and on thickness of the plates. Linear and non-linear FEM modelling is able to explain some of the materials response.