Parametric design of multilayered piezoelectric/piezomagnetic transducers with periodic interfacial electrodes based on fracture mechanics analysis

This paper studies the parametric design of multilayered piezoelectric/piezomagnetic (PE/PM) ceramic transducer with periodic interfacial electrodes based on fracture mechanics analysis. The analysis of multilayered PE/PM transducer under electrically actuated mode is carried out by means of solving the magneto-electroelastic problem of a PE/PM bi-layer, where the inner interfacial electrode is electrically charged and periodic conditions are used. Due to the singular stress distributed on the inner side of the electrode ends, cracks are prone to nucleate and propagate along the interfaces. The weight function method and linear superposition are used to find the Stress Intensity Factor (SIF) around the crack tip. Parametric discussion was carried out for the dependence of SIF on the layer thickness ratio as well as the position of the interfacial electrode. Analysis reveals that, under the same electric load, a thicker piezoelectric layer will lead to a lower SIF. This suggests that, for the bonded interfaces with certain fracture toughness in the piezoelectric/piezomagnetic transducer, the design with a thicker piezoelectric layer can sustain a higher threshold electric load and the transducer can accommodate more electric charges under the critical condition. However, concerning with the crack extension rate defined as the crack extension induced by per unit electric charge increase, the design with a thinner piezoelectric layer will find a lower and relative small crack extension rate, while for the case of thicker piezoelectric layer, the crack extension rate enhances significantly as crack propagates, which may lead to fatal destruction of the device.