LOCAL FLANGE BUCKLING AND ITS RELATION TO ELASTIC SPRINGBACK IN FORMING OF ALUMINUM EXTRUSIONS

This paper presents a numerical and experimental investigation of inte ractions between local buckling and elastic springback in forming of t hin-walled aluminium extrusions. The cross sectional distortions that are present in typical aluminium sections prior to elastic unloading c annot be disregarded. This is the case even when these beams are bent with relative large radii. The numerical analyses presented herein hav e shown that both element type and formulation have to be chosen caref ully in order to correctly predict elastic recovery. Full integration tri-linear brick elements in combination with the assumed strain formu lation have proven to be preferable to linear thick-shell, conventiona l full integration brick elements as well as reduced integration eleme nts.