Strain incompatibility between dissimilar piezoceramics with a penny-shaped interfacial electrode

Debonding between metallic electrodes and piezoelectric materials is a common cracking failure phenomenon observed in piezoelectric devices. In an attempt to explore the failure mechanism, an electroelastic model made of two jointed dissimilar piezoelectric ceramics with a thin circular interface electrode was proposed. Explicit solution to the entire electroelastic field perturbed by the electrode is obtained by solving the associated boundary-value problem. It shows that the electroelastic field near the electrode edge bears an inverse square-root singularity. However, the normal stress, strain, electric displacement, and electric field vanish along the interface out of the electrode, while the corresponding radial components disappear within the electrode surface. Moreover, in the case of two dissimilar ceramics polarized in opposite directions, the normal strain shows strong incompatibility across the electrode surface, and the normal stress reaches its peak value at a distance less than half of the electrode radius above and below the electrode surface. Numerical results are presented for PZT-4+/PZT-4− and PZT-4+/PZT-5H− with a circular interface electrode.