Integrity of piezoceramic patch transducers under cyclic loading at different temperatures

Abstract

In this study the loading limits, damage behavior and long-term integrity of piezoceramicpatch transducers, based on monolithic PZT (lead zirconium titanate) wafers (PIC 255),were investigated. The study involved quasi-static and long-term cyclic testing undertensile and compressive mechanical loading of the patches, at different temperatures. Astrain-cycle lifetime diagram was established for tensile loading at room temperature, and+60,+100 and−40 °C. In all cases of tensile loading, cracking in the PZT ceramic was found to bethe relevant failure mechanism which was shown to be correlated with theobserved degradation of sensor performance of the patches. No mechanicaldamage was found under compressive loading at strain levels of up to−0.6%. Finite element (FE) analyses were performed using 3D material modeling withelectromechanical coupling, achieving very good predictability of the sensor and actuatorperformance. Analytical calculations and numerical simulation were used to interpretexperimental findings and to allow the transfer of results to various applications. Based onmicro-structural investigations of the cracked PZT wafers and FE simulation, fracturemechanics analyses of the local stress situation in the PZT ceramic were carried out.