Stretch bending of aluminium extrusions for car bumpers

Stretch bending of two generic aluminium bumper sections are investigated experimentally and numerically. Six different stretch bending procedures, herein denoted tensile sequences, are studied. Laboratory tests are performed for one of these sequences, finding that the numerical model represents the observed behaviour satisfactorily. A sequence with constant tensile force during bending seems to be favourable with respect of cross-section deformations. These deformations increase with additional tensile force, whilst the springback during unloading shows a decreasing tendency. Post-stretching operations or membrane-induced stretch bending are also investigated, finding that these sequences result in a disadvantageous cross-section distortion.