A note on tensile testing of poled and unpoled piezoelectric ceramics

Tensile tests were carried out on unpoled and poled soft lead zirconate titanate (PZT) ceramic materials: APC #855 (APC International) and PZT-5H (Morgan Electro Ceramics). The tests were performed on a dog-bone specimen with holes at its edges. A methodology is presented for carrying out these tests. A tensile stress was applied by means of Kevlar strings through the specimen holes. The poling direction was perpendicular to the longitudinal specimen axis. For the poled specimens, two electrical boundary conditions were applied, namely, E = 0 and D = 0. Strains were measured at four points on the sample. For each specimen, the bending percentage was calculated. For all specimens, stress-strain curves were found to be initially linear; at a strain of approximately 0.0001, the curves became nonlinear. Young's modulus was measured in the linear region of the stress-strain curve. Young's modulus values were highest for the poled material with an open circuit boundary condition (D = 0) and lowest for the unpoled material .