Stress-Invariants-Based Anisotropic Yield Functions and Its Application to Sheet Metal Plasticity

The yield criterion, or so-called function, plays an important role in the study of plastic working a sheet because it governs deformation properties during plastic-forming process. In this paper, we propose novel anisotropic function useful for describing behavior various sheets. proposed includes version second stress invariant J2 and third J3. can explain sheets by introducing parameters α β also exhibits both symmetrical asymmetrical surfaces. included model were determined with optimization algorithm from uniaxial biaxial experimental data under proportional loading path. study, validity was verified comparing surface shape, normalized value, Lankford coefficient R-value derived results. Applications functions to aluminum showed yielding and, pure titanium sheets, asymmetric behavior; thus, shown that curve types materials be predicted reasonably using new function.