Strain Rate and Porosity Effect on Mechanical Characteristics and Depolarization of Porous Poled PZT95/5 Ceramics
Shock wave compression of poled PZT95/5 ceramics results in rapid depoling and a release of bound charge. Porous PZT95/5 ceramics are superior to dense ceramics in high-voltage breakdown resistance under shock-wave loading. In this article, the mechanical and electrical responses of porous poled PZT95/5 ceramics under uniaxial stresses at different strain rates were investigated using the servo-hydraulic MTS810 universal test machine and the improved split Hopkinson pressure bar system. The engineering stress vs. axial and radial engineering strain curves of porous poled PZT95/5 ceramics under different strain rates exhibit anomalous nonlinear behavior. The nonlinear behavior and depolarization mechanism of porous poled PZT95/5 were attributed to the domain switching and phase transformation. By comparing the stress–strain curves of the porosity porous poled PZT95/5 ceramics at different strain rates, an obvious strain rate sensitivity of mechanical behavior can be found, and the strain rate sensitivity decreases with the increase of porosity. The critical stress of domain switching and phase transformation and the strength increased with increasing strain rate. In addition, their normalized values showed a logarithmic relationship with the strain rate. Finally, we suggest that the maximum polarization released is nearly independent of stress state and strain rate, and it only depends on the porosity.