STUDY ON FRACTURE BEHAVIOR OF FERROELECTRIC CERAMICS UNDER COMBINED ELECTROMECHANICAL LOADING BY USING A MOIR(?) INTERFEROMETRY TECHNIQUE

This paper discusses an in situ observation of fracture behavior around a crack tipin ferroelectric ceramics under combined electromechanical loading by use of a moiré interferometrytechnique.The deformation field induced by the electric field and the stress concentration near thecrack tip in three-points bending experiments was measured.By analysis of the moiré images it is foundthat under a constant mechanical load,the electric field almost has no effect on the crack extensionin the case that the directions of the poling,electric field and crack extension are perpendicular toeach other.When the poling direction is parallel to the crack extension direction and perpendicular tothe electric field,the strain decreases faster than that calculated by FEM with and without electricalloading as one goes away from the crack tip.In addition,as the electric field intensity increases,thestrain near the crack tip increases,and the strain concentration becomes more significant.