Effects of graded properties on the impact response of an interface crack in a coating/substrate system subjected to antiplane deformation

摘要

An elastodynamic analysis of an interface crack in coated media with functionally graded properties is performed under the condition of antiplane shear impact. The graded material exists as a nonhomogeneous interlayer between the dissimilar, homogeneous phases of the coating/substrate system or as a nonhomogeneous coating deposited on the substrate. The material nonhomogeneity is represented in terms of power-law variations of shear modulus and mass density. Based on the use of the integral transform technique, formulation of the transient crack problem is reduced to having to solve a Cauchy-type singular integral equation in the Laplace transform domain. Via the inversion of the Laplace transforms, the values of dynamic mode III stress intensity factors are obtained as a function of time. In the numerical results, the effects of material and geometric parameters of the coating/substrate system with the graded, nonhomogeneous constituent are illustrated, addressing the dynamic load transfer and overshoot characteristics of the transient crack-tip behavior. Furthermore, a comparison is made with the dynamic behavior of the interface crack in a discretely coated material system. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.