This paper presents an analysis of crack problemsin homogeneous piezoelectric or on the interfaces between twodissimilar piezoelectric materials based on the continuity ofnormal electric displacement and electric potential across thecrack faces. He explicit analytic solutions are obtained for asingle crack in an infinite piezoelectric or on the interface ofpiezoelectric bimaterials. For homogeneous materials it is foundthat the normal electric displacement D_2, induced by the crack,is constant along the crack faces with depends only on the remoteapplied stress fields. Within the crack slit, the perturbed electricfields induced by the crack are also constant and not affected bythe applied electric displacement fields. For bimaterials, generallyspeaking, an interface crack not affected by the applied electricdisplacement fields. For bimaterials. Generally speaking, aninterface crack exhibits oscillatory behavior and the normalelectric displacement D_2 is a complex function along the crackfaces. However, for bimaterials, having certain symmetry, inwhich an interface crack displays no oscillatory behavior, it isobserved that the normal electric displacement D_2 is also acrossthe interface. Energy release rates are established forhomogeneous materials and bimaterials having certain symmetry.Both the crack front parallel to the poling axis and perpendicularto the poling axis are discussed. It is revealed that the energyrelease rates are always positive for stable materials and theapplied electric displacements have no contribution to the energy release rates.
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