<title>Deformation and strength behavior of a soft PZT ceramic</title>

Abstract

Nonsymmetric deformation in tension and compression was measured for a PZT-ceramic. Besides direct measurements in tension and compression tests a method to obtain the nonsymmetric deformation from bending tests was developed. Large differences in strength between tensile and bending tests were found and related to the nonlinear stress distribution in the bending bars and to the statistical size effect. The deformation behavior of PZT-ceramics is mainly investigated under compressive load. Non-linear stress- strain curves were observed and interpreted by domain switching processes. Early results on electroceramics were reported by Subbarao et al. for polycrystalline barium titanate. From these results Subbarao et al. concluded that the Young's modulus would be different in tension and compression. A more detailed analysis of their data shows significant plastic strain contributions in tension and negligible compressive plastic strains, i.e. a non-symmetry in plastic strains. This behavior must have consequences on strength in bending bars due to non-linear stress distribution.