THE EFFECT OF A LAYER ON A 3-D CRACK WITHIN THE SUBSTRATE OF A LAYER SUBSTRATE SYSTEM/

A new numerical scheme is described for calculating the elastic held i n an elastic layer/half-space caused by an embedded crack subjected to a general internal pressure and shear traction in the substrate. This scheme is based on the body force method associated with Green's func tions for two perfectly bonded half-spaces, and the free surface of th e coating layer is modeled by a much larger crack than the substrate c rack. Thus, the surface displacement of the coating layer, which is us eful for many applications, can be easily estimated from the crack ope ning displacements of the larger crack. Although the method can be app lied generally, for simplicity, only a penny-shaped crack in a substra te subjected to a uniform tension at infinity is considered in this an alysis. The effects of layering on stress intensity factors and surfac e displacements were also investigated.