Numerical Investigation into the Effect of Uniaxial and Biaxial Pre-Strain on Forming Limit Diagram of 5083 Aluminum Alloy

In this paper, numerical simulations are carried out to determine the forming limit diagram (FLD) of 5083 aluminum alloy. The aim is to predict the effect of strain path change on the forming limit curve (FLC) of this alloy. For this purpose, out‐of‐plane formability test method with hemispherical punch was simulated by using commercial finite element software, ABAQUSE 6.9. In the first stage, square blanks were modeled and then some of them were pre‐strained uniaxially by tension test and some others were pre‐strained biaxially by stretching over the hemispherical punch. In the second stage, the formability test specimens’ models were prepared by trimming the pre‐strained blanks with the longitudinal axis parallel and perpendicular to the rolling direction. For trimming, a program was written in MATLAB 7.6 which could determine the new elements and introduce their properties to the FEM model. Ductile fracture criteria were used to predict failure. Furthermore, forming limit stress diagram (FLSD) was determined. The numerical results were compared with the experimental findings. Uniaxial pre‐straining increased and shifted the FLC to the left hand side of the diagram for both parallel and perpendicular to the rolling direction. Biaxial pre‐straining shifted the FLC to the right hand side of the diagram for both directions, and also decreased the FLC for the specimens parallel to the rolling direction.