A Study of Theories of Fracture Under Combined Stresses

Abstract

Experimental data are presented for a cast nodular iron and for high-silicon cast iron materials which represent limiting conditions of ductility in a test of fracture theories. Data of other pertinent investigations are reviewed and various failure theories are discussed with regard to their applicability. It is concluded that failure under combined stresses of brittle materials can be predicted adequately by applying a notch modified distortion energy criterion. However, other criteria are also applicable. Since criteria for the failure of brittle materials are conspicuously phenomenological, the application of solid state and dislocation theory, to explain the initiation and growth of a crack in a heterogeneous structure under combined stresses, has been discussed.