Fracture under combined loading

Theoretical and experimental studies were carried out to predict the initial crack propagation angle in elastoplastic materials under small scale yielding subjected to mixed mode loading in plane stress conditions. The proposed method maximizes the principal stresses product, and this is shown to be equivalent to maximizing the total strain energy density or dilational strain energy density when applied along the elastoplastic boundary, eliminating the arbitrariness in selecting the point at which the criterion is to be applied. Experimental investigations carried out using different metals and isotropic composites exhibit very good agreement with theoretical predictions for all crack angles.