Impact response of a surface crack in a coating/substrate system with a functionally graded interlayer: antiplane deformation

In this paper, the elastodynamic crack problem for a coating/substrate system with a functionally graded interfacial zone is investigated under the condition of antiplane shear impact. With the interfacial zone being modeled by a nonhomogeneous interlayer having the power-law variations of shear modulus and mass density, the coating is assumed to contain an embedded or an edge crack perpendicular to the boundaries. Laplace and Fourier integral transforms are used to reduce the transient problem to solving a singular integral equation with a generalized Cauchy kernel in the Laplace transform domain. The time dependence of the crack-tip response in the physical domain is recovered via the numerical inversion of the Laplace transforms and the values of dynamic mode III stress intensity factors are provided as a function of time, As a result, the effects of material and geometric parameters of the current coating/substrate system on the dynamic load transfer and overshoot characteristics over the corresponding elastostatic solutions are addressed. (C) 2004 Elsevier Ltd. All rights reserved.