Numerical Prediction of Ductile Fracture in Bi-Axially Stretched Sheet Metal

Ductile fracture is characterized by nucleation and growth of voids with deformation and ends with void coalescence leading to fracture. The Gurson-Tevergaard model is a widely accepted model for describing the ductile flow of voided metals. This model does not consider the interaction between voids. Many coalescence models are being introduced to define the onset of fracture and they are based on different hypotheses considering the carrying capacity of ligaments between voids. Literature includes many void Coalescence models; namely Thomason, Pardoen and Hutchinson (P&H), Benzerga, Ragab, and McClintock. In this work, FEA is used to model materials obeying Gurson function on biaxial stretching of sheet metal. The coalescence criterions are introduced to the FEA solver, Abaqus via a user subroutine. The onset of coalescence is determined and compared to experimental results. It is found that Ragab criterion gives fracture strains close to the experimental results.