New approach to describe load rotation-induced anisotropy in ductile fracture criteria

Abstract

Ductile fracture criteria can be of importance for assessing the manufacturability as well as the performance in service of sheet metal components. Recent results show that an anisotropy in terms of equivalent fracture strain can evolve due to load rotations which may not be predicted by common – potentially anisotropic – fracture criteria. Hence, a novel type of fracture criteria is introduced containing a new damage-related variable named effective load rotation indicator. Its phenomenological fracture strain dependence is covered by a first-order approximation, enabling the computation of increasing or decreasing failure levels. First parameters for the new criterion are identified for own uniaxial tension experiments with a dual phase steel and for literature data on a magnesium alloy for simple shear after uniaxial tensile prestrain. The new fracture criteria form could enhance the prediction quality in the numerical design phase of critical components exhibiting complicated load paths in a user-friendly postprocessing way.