TENSILE STRESS-STRAIN BEHAVIOR OF PIEZOELECTRIC CERAMICS

Fracture strength and stress-strain behavior under tensile stress in piezoelectric ceramics have been investigated with special emphasis on the effects of poling conditions. The materials used in this work are the commercial piezoelectric ceramics, PbZrO3-PbTiO3 (PZT) and BaTiO3. First, an attempt was made to evaluate the tensile strength properties of samples having a specially designed specimen geometry. In the actual tensile test, fracture did not occur at the gripping portion at all, indicating usefulness of the present tensile test method. Not only fracture strength, but also elastic properties, tensile modulus and Poisson's ratio, were evaluated. Second, an investigation was performed on the stress-strain behavior under tension in this material. As a result. stress-strain response under tension was confirmed to be nonlinear. The nonlinearity in the stress-strain relationship under compression loading has already been reported by some investigators. However, very little work has been done on the tensile stress-strain relationship studied in this paper. Third, acoustic emission monitoring was performed simultaneously during tensile tests, and thus the tensile failure process in piezoelectric ceramics was discussed.