Ferroelastic Properties of PZT: Characterization under Compressive and Tensile Stress, Finite-Element Simulation, and Lifetime Calculation

Finite-element (FE) simulations, based on a phenomenological nonlinear constitutive model, were carried out to show the impact of ferroelastic switching on compressive and tensile loading of a soft and hard ferroelastic polycrystalline lead zirconate titanate ceramic (PbZr_1-xTi_xO₃, PZT). Hereby, a model assembly is used that simulates mechanical stresses generated by the contact of a ceramic element with a concave counterpart. In order to parameterize the constitutive model, the elastic and piezoelectric tensors are determined by the small signal resonance method and by the direct measurement under compressive/tensile loads. In addition, the large field ferroelectric and ferroelastic behavior of polarization and strain were characterized. The simulations show that the tensile stress level within the piezoceramic is much lower compared to a linear elastic model, which is related to ferroelastic switching. This is demonstrated to have a significant influence on mechanical lifetime predictions. To validate the parametrized FE model, a four-point bending experiment was used. The comparison of the calculated and measured strain on the compressive and tensile sides of the sample showed very good correlation.