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Concepts for a lighter seat backrest structure using a MgMnCe-type alloy have been developed, dimensioned and evaluated. The underlying predevelopment process is based on numerical as well as experimental methods at different levels. At component level, profile tests in bending reveal large deformation without local failure. This deformation makes the use of closed rectangular profiles promising for the application in seat frame structures. Two alternative structural concepts have been developed utilizing different joining technologies - a primary concept using friction stir welding and a secondary one basing on injection adhesive bonding. Both concepts use the same magnesium frame. In the consideration and development of associated process routes, the major challenge has been the magnesium-steel joint between frame and gusset. For welding, the joining direction is essential. Therefore, the magnesium material needs to be accessible.

Cylindrical extrusions of magnesium AZ31B were subjected to quasi-static axial compression and cutting modes of deformation to study this alloy’s effectiveness as an energy absorber. For comparison, the tests were repeated using extrusions of AA6061-T6 aluminum of the same geometry. For the axial compression tests, three different end geometries were considered, namely (1) a flat cutoff, (2) a 45 degree chamfer, and (3) a square circumferential notch. AZ31B extrusions with the 45 degree chamfer produced the most repeatable and stable deformation of a progressive fracturing nature, referred to as sharding, with an average SEA of 40 kJ/kg and an average CFE of 45 %, which are nearly equal to the performance of the AA6061-T6. Both the AZ31B specimens with the flat cutoff and the circumferential notch conditions were more prone to tilt mid-test, and lead to an unstable helical fracture, which significantly reduced the SEA.