AN AXISYMMETRIC PROBLEM OF A PARTIALLY INSULATED CRACK EMBEDDED IN A GRADED LAYER BONDED TO A HOMOGENEOUS HALF-SPACE UNDER THERMAL LOADING

The elastic-static problem of a partially insulated axisymmetric crack embedded in a graded coating bonded to a homogeneous substrate subjected to thermal loading is considered. The coating's gradient is parallel to the axisymmetric direction and is orthogonal to the crack plane. The graded coating is modeled as a nonhomogeneous medium with an isotropic constitutive law. Using Hankel transform, the heat conduction and the plane elasticity equations are converted into singular integral equations, which are solved numerically to yield the temperature distribution and the crack tip stress intensity factors. The Finite Element Method was additionally used to model the crack problem. The main objective of this paper is to study the influence of the material nonhomogeneity, partial insulation of the crack faces and the crack position on the stress intensity factors for the purpose of gaining better understanding on the behavior of graded coatings.