Crack and contact problems in functionally graded materials

In this article the failure of FGM substrates due to sliding contact is considered. The first stage of the failure process involves crack initiation on the surface of FGM substrates or FGM coatings bonded to homogeneous substrates caused by the tensile stress due to friction forces. The second stage is the crack propagation under repeated loading. After a brief review of the related contact problem leading to the calculation of complete stress state on the surface, the coupled crack-contact problem for an FGM substrate loaded by a rigid stamp is considered and the stress intensity factors are calculated.