Exploration of ductile, brittle failure characteristics through a two-parameter yield/failure criterion

A criterion is developed for determining whether a particular mode of failure is expected to be of ductile type or brittle type depending upon both the material type and the particular state of stressing the isotropic material to failure. The material type is specified by an α index obtained from two specific failure properties and a recently formulated failure theory. The ductile versus brittle criterion then involves the α material specification and the mean normal stress part of the imposed stress state. Several illustrative examples are given for different stress states and a spectrum of materials types. Closely related to the failure mode types are the orientations of the associated failure surfaces. In uniaxial tension, the present method shows a distinct failure orientation transition from ductile type to brittle type as the type of material changes.