The interface crack problem for a nonhomogeneous coating bonded to a homogeneous substrate

The debonding problem for a composite layer that consists of a homogeneous substrate and a nonhomogeneous coating is considered. It is assumed that the problem is one of plane strain or generalized plane stress and the elastic medium contains a crack along the interface. It is further assumed that the thermomechanical properties of the medium are continuous functions of the thickness coordinate with discontinuous derivatives and the kink line of the property distributions corresponds to the ''interface''. The mixed-mode crack problem is formulated for arbitrary crack surface tractions and sample results are given for uniform normal and shear tractions. The main variables in the problem are two dimensionless length parameters and a nonhmogeneity constant. Calculated results consist of primarily the stress intensity factors and the strain energy release rate and are partly intended to provide benchmark solutions for further numerical studies.