A note on a proposed general criterion for brittle and ductile fracture in materials and structures

A material endures elastic–plastic deformation to the point where the mean stress reaches the maximum sustainable equi-cohesive bonding stress. In this note a proposed new ductile fracture criterion is developed from the theory of fracture toughness under different mean stress from that of the tensile test. Brittle fracture occurs during elastic deformation, which latter is induced by variation in the mean stress.