Crack growth in ferroelectrics driven by cyclic electric loading

点击翻译按钮获取中文摘要

Prior work from the literature of non-conducting cracks indicates that ferroelectrics can exhibit crack growth due to electrical cycling only with the electrical field perpendicular to the crack propagation direction. A clear quantitative and mechanistic understanding about the influences of prior poling, polarity and frequency of the cyclic electric field, however, is still missing. In the experimental part of this project, crack propagation of through thickness cracks in DCB specimens in PZT due to electrical cycling will be investigated with and without a mechanical preload. Switchable strain and macroscopic material characterization will also be performed. The theoretical part of the project will provide switching zones for 90° switching, for 180° switching and will include the piezoelectric effect in order to compute the stress intensity factor at the crack tip via an evaluation of the tractions along a contour integral around the crack tip. A further consistency check of the model is afforded by calculating the specimen geometries where a stable crack path is obtained under mixed mechanical and cyclic electrical loading.