Electroelastic field concentration by circular electrodes in piezoelectric ceramics

The electroelastic field concentration due to circular electrodes in piezoelectric ceramics has been discussed through theoretical, numerical and experimental characterizations. This paper consists of two parts. In the first part, the problem of a surface electrode attached to a semi-infinite piezoelectric solid was formulated by means of Hankel transforms and the solution was solved exactly. The displacements and electric potential were expressed in closed form. In the second part, finite element analysis was carried out to study electroelastic fields in piezoelectric disks containing circular electrodes of different radii by introducing a model for polarization switching in local areas of electroelastic field concentration. A nonlinear behavior induced by localized polarization switching was observed between the strain and the voltage applied to the electrode. Experiments were also conducted to study the strain state near the electrode tip. Comparison of the predictions by the present model with experimental data is conducted and pertinent conclusions are drawn. This work is the first attempt to obtain nonlinear electroelastic fields around a circular electrode in piezoelectric ceramics and validate the polarization switching model.