Concepts for a Seat Backrest Structure Using Extruded Magnesium Profiles

Abstract

In large-scale production of vehicle seat structures, high and ultra-high strength steel alloys prevail because of challenging requirements, mainly concerning passenger safety. The project FUMAS (Functionally integrated magnesium lightweighting for automobile seat structures) aimed at weight reduction by using extruded magnesium (an alloy of the type MgMnCe) and novel process routes in manufacturing. Concepts for a lighter seat back structure have been developed, dimensioned and evaluated. The underlying predevelopment process is based on numerical as well as experimental methods at different levels - coupon, generic component and demonstrator level. Good-natured, ductile failure behavior has been observed using rectangular closed profiles in bending at high testing speeds, which makes the use of the alloy promising for seat applications. The proposed backrest structure builds on a three-part magnesium frame assembly that is joined to so-called mobile steel gussets at the transition to the seat area. Two alternative structural concepts have been developed utilizing different joining technologies - friction stir welding and injection adhesive bonding.