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The targeted use of aluminium extrusions in automotive crashworthiness applications is a way for a significant weight reduction. Indeed, if the energy absorption is proportional to the mechanical characteristics, it takes important benefits of the thickness increase and of the use of closed sections, advantageously multicellular, allowed by the use of aluminium profiles. But in the case where the material and the geometry of the extruded product are not adapted, some undesirable failures may appear during the crash. Most of the time, these failures remain localised, and have no consequence on the energy absorption levels. Nevertheless, it appears important to predict their apparitions, and to adapt the alloys temper to reduce or eliminate it. An experimental and numerical program was carried out to relate the behaviour of extrusions submitted to different crash conditions. The results were used to fit a damage mechanics based numerical model.

Important design requirements for an outer autobody panel are stiffness and dent resistance performance which depend on panel geometry and mechanical properties of the sheet. Specific grades of PECHINEY 6016, named as DR for « dent resistance », were designed for enhanced strengthening during paint baking. An experimental program was carried out to relate panel thickness and strength to both stiffness and dent resistance in quasi-static and dynamic (10-15km/h) conditions. Tests were performed on non prestrained flat and curved 6016 panels of different thicknesses and paint bake strengths. Steel grades and thicknesses typical of outer panels were used for comparison. Local stiffness, independent of strength, was confirmed to increase with panel curvature and sheet thickness. Static and dynamic dent resistance, which increase with sheet thickness and strength, were found to depend on panel curvature.