EFFECTS OF STATIC ELECTRIC FIELD ON THE FRACTURE BEHAVIOR OF PIEZOELECTRIC CERAMICS

摘要

The paper gives an overview on experimental observations of thefailure behavior of electrically insulating and conducting cracks in piezoelectric ce-ramics. The experiments include the indentation fracture test, the bending test onsmooth samples, and the fracture test on pre-notched (or pre-cracked) compact ten-sion samples. For electrically insulating cracks, the experimental results show a com-plicated fracture behavior under electrical and mechanical loading. Fracture dataare much scattered when a static electric field is applied. A statistically based frac-ture criterion is required. For electrically conducting cracks, the experimental resultsdemonstrate that static electric fields can fracture poled and depoled lead zirconatetitanate ceramics and that the concepts of fracture mechanics can be used to mea-sure the electrical fracture toughness. Furthermore, the electrical fracture toughnessis much higher than the mechanical fracture toughness. The highly electrical fracturetoughness arises from the greater energy dissipation around the conductive crack tipunder purely electric loading, which is impossible under mechanical loading in thebrittle ceramics.