Moiré interferometry applied to ferroelectric ceramics

This paper introduces how to in situ observe fracture behavior around a crack tip in ferroelectric ceramics under combined electromechanical loading by use of a moiré interferometry technique. The deformation field induced by electric field and stress concentration near the crack tip in three-points bending experiments was measured. By analysing the moiré interferometry images it is found that under a constant mechanical load, an electrical field has no effect on crack extension in the case that the directions of the poling, electric field and crack extension are perpendicular to each other. When the poling direction is parallel to the crack extension direction and perpendicular to the electric field, strain decreases faster than values predicted by the theoretical analysis as the distance away from the crack tip increases. In addition, as the electric field raises the strain near the crack tip increases, and the strain concentration phenomena becomes more significant.