The Griffith Medal Lecture: The fracture mechanics of soft solids

A review is given of describing the fracture of soft solids using the notion of energy release rate as proposed by Griffith. Soft solids have low modulus and, sometimes, low yield stresses which result in self-blunting when cracked specimens are loaded laterally. The resulting blunt cracks bring into play the requirement that some critical stress must be achieved as well as the energy release rate. This two criteria analysis is explored and conditions for sharp crack failure, blunt crack failure with elevated apparent toughness and ductile tearing when the critical stress is not achieved are described.