SURFACE CRACKS IN TRANSFORMATION TOUGHENING CERAMICS

This paper presents a complete R-curve analysis for a single surface c rack and an array of equally spaced parallel surface cracks in transfo rmation toughened ceramics (TTC). The problem is reduced to the soluti on of a pair of singular integral equations in which the dislocation d ensity function and the transformation zone boundary are the unknown f unctions. The form of the equations does not depend on the number of s urface cracks being studied; only the weight functions are different. The singularities of the weight functions and of the dislocation densi ty functions at the crack tip and at the intersection of the crack by the transformation zone wake are analytically isolated for accurate nu merical integration of the integral equations.