On fracture testing of piezoelectric ceramics

Abstract

Fracture tests carried out on unpoled and poled PZT-5H four-point bend specimens are presented in this paper. The crack faces were parallel to the poling direction. Both mechanical loads and electric fields were applied to the poled specimens. The experimental results were analyzed by means of the finite element method and a conservative M-integral including the crack face boundary conditions. Fracture tests on fourpoint bend PIC-151 specimens with the crack faces perpendicular to the poling directions were also analyzed here; the experimental results were taken from the literature. A mixed mode fracture criterion is proposed for piezoelectric ceramics. This criterion is based upon the energy release rate and two phase angles. This criterion was implemented with experimental results from the literature and from this investigation. Excellent agrement was found between the fracture curve and the experimental results of the specimens with the crack faces perpendicular to the poling direction. With some scatter, reasonable agreement was observed between the fracture curve and the experimental results of the specimens with crack faces parallel to the poling direction.

A supplementary study on fracture tests of piezoelectric material: cracks parallel to the poling direction

“…The criterion may be easily extended for other relative crack and poling orientations. This criterion was first presented by Motola et al (2009a) for a crack both perpendicular and parallel to the poling direction. In that study, the fracture criterion was implemented with tests carried out by Jelitto et al (2005a) on PIC-151 with the crack perpendicular to the poling direction.…”

“…The test results fit the failure curve quite well. In addition, the fracture criterion was applied to tests which were performed on PZT-5H with the crack parallel to the poling direction (Motola et al 2009a). In that case, there was much scatter of the test data about the failure curve.…”

“…There have been many fracture tests carried out on piezoelectric material (see Tobin and Pak 1993;Park and Sun 1995a;Wang and Singh 1997;Lynch 1998;Fu and Zhang 2000;Shindo et al 2001Shindo et al , 2005Schneider et al 2003;Zhang et al 2004;Jelitto et al 2005a; Motola et al 2009a). There is a contradiction between some of the studies.…”

“…Fracture criteria have been presented by Suo (1991), Gao et al (1997), Fulton and Gao (2001), Jelitto et al (2005a,b), Park and Sun (1995b) and Motola et al (2009a). Each of these is based on the energy release rate.…”

“…In Motola et al (2009a), the derivation for the energy release rate begins with the expression (Suo et al 1992)…”