Plastic Constitutive Equation based on Non-Associated Flow Rule for Anisotropic Metals (3rd Report)

Abstract

For successful sheet metal forming, avoiding fracture during forming plays significant role; however, due to the increasing application of difficult-to-press metals, it is still a challenge. Although there have been many direct type fracture prediction methods, in this study, material fracture is defined as a final form of local bifurcation, which can be analyzed mechanically reasonably by using a local bifurcation theory. To represent local bifurcation appropriately, we have adopted the 3D bifurcation theory based on the anisotropic plastic constitutive equation in which the rotation of stress rate tensor is allowed to express plastic instability. To evaluate this constitutive equation, a non-associated flow rule material model that has been proposed by the author is applied. In this report, framework of the proposed fracture prediction is described and some numerical investigations are presented.