Iron (Fe) has been shown to greatly influence the formability of aluminum alloys. Increased Fe results in a greater number of second-phase particles, which act as initiation sites for void damage. Four AA6111 Fe-variants have been studied, using a cantilever bend test apparatus, to determine the effect of void damage on bendability. To simulate the development of void damage and shear band localization, the kinematic hardening Gurson-Tvergaard-Needleman (GTN) equations have been reformulated for use in LSDYNA, a commercial finite element method (FEM) code.

Bendability was found to be a function of reduced grain size and increased void damage, with increasing Fe content. Numerical predictions show that the greater curvature of the kinematic hardening yield surface allows shear bands to initiate more easily than under isotropic hardening conditions. Furthermore, the predictions were also found to be highly dependent upon the level of triaxial stress, the element size and aspect ratio, as well as the void nucleation parameters of the GTN equations.