7 - Lightweight construction materials and techniques

Abstract

The key to lightweight construction lies in a combination of structurally efficient design and the exploitation of advanced materials technology and construction techniques. Steel, the traditional building material for the structures of volume cars, has excellent property combinations if it can be exploited in structurally efficient designs, alloyed to produce high strength sheet, then formed and fabricated by such techniques as hydro forming and laser welded tailored blanking. Light (high specific strength and rigidity) alloys of aluminum, magnesium, and titanium also have a place and advanced polymer composite systems have already proven themselves in race car and similar applications to provide ultra-light solutions. The use of metal platform base structures and reinforced plastic body shells is established technology for low to medium production cars. The concept of composite construction is to use reinforced plastics in more intimate combinations with metals in such a way that permits the most efficient usage of thin-walled sheet metal structures together with plastic systems that stabilize them against buckling. Hybrid metal/plastic (stabilized core) systems offer considerable potential to the constructor who is prepared to depart from conventional manufacturing technology and embrace production systems geared to the technique. Design techniques for load-beating plastics inevitably differ from those applying to elastic materials and continuous attention must be paid to creep properties when predicting stresses and deflections. Plastic material specifications must state service temperatures and duration of loads when using the so-called pseudo-elastic design method.