Crack tip shielding and anti-shielding effects of the imperfect interface in a layered piezoelectric sensor

The purpose of the present work is to study the effect of an imperfect interface on the fracture behavior of a layered piezoelectric sensor. For mathematical convenience, the problem is investigated under mode III-a simple case in fracture mechanics. Fracture analysis is performed by the methods of Fourier integral transform and Cauchy singular integral equation. Parametric studies on the numerical results of energy release rate reveal the crack tip shielding and anti-shielding effects of the imperfect interface. When the inclined angle of crack is less than 0.1 pi, the imperfect interface may shield the crack, however, when it is larger than 0.2 pi, the crack may be anti-shielded. If the distance between a crack tip and the imperfect interface is less than two times of the crack length, the shielding or anti-shielding effect is remarkable, and otherwise it is negligible. Finally, the crack tip shielding and anti-shielding effects of the mechanical imperfection are generally more remarkable than those of the dielectric imperfection. (C) 2009 Elsevier Ltd. All rights reserved.