Interfacial forces and the fundamental nature of brittle cracks

Abstract

A new conception of brittle fracture processes is presented. It is proposed that the crack-tip structure is immutably sharp at the atomic level, such that the attendant growth laws are uniquely determined by the stress intensity factor K of ‘‘fracture mechanics’’ origin. Threshold features in the measured v(K) function for crack growth in interactive environments, previously put forward as evidence for fundamental changes in the tip structure by blunting, are shown to be more consistent with a negative K contribution from interfacial adhesive forces. These adhesive forces should be determinable from the crack velocity characteristics.