A design method for rectangular hollow sections in bending

Local deformation of individual cross-sectional members is of great interes t in the bending of aluminium alloy extrusions for automotive applications. The primary concern is the impact of such distortions on the manufacturabi lity of components as well as the dimensional tolerances of the final build . This paper presents analytical models for the determination of local post -buckling and suck-in deformations in bending. The models are based on the deformation theory of plasticity combined with an energy method using appro priate shape functions. The analytical predictions are verified with experi mental results. Based on the present findings, an approximate design method for evaluation of the bendability of sections in industrial forming operat ions is proposed. The results show that the slenderness ratio (blt) and the width of the flange are the main parameters related to the bending radius at the onset of plastic buckling and the magnitude of local deformations, r espectively Material parameters have proven to be relatively more important to buckling radius than to deformation of individual cross-sectional membe rs. Although there is some discrepancy between the experimental and theoret ical results at tight nominal bend radii, the overall correlation is surpri singly good. It is, therefore, concluded that the present approach provides an efficient method for the evaluation of the bendability of rectangular h ollow sections. (C) 2001 Elsevier Science B.V. All rights reserved.