Under the skin: the new SL body shows the evolution of the species Car News

The future Mercedes-AMG SL has a clean body design aimed at making it as light and stiff as possible using a combination of techniques and materials that have continued to evolve over the years. The first unit-built car, where the chassis and bodywork are combined into a single unit carrying the load of the powertrain and suspension, was the Lancia Lambda in 1923. It and those that followed were fairly straightforward, made of mild steel. fairly thick panels spot welded together and painted.

Modern bodywork is a complex system of materials and assembly techniques, some of which are aerospace-derived and sophisticated. In the late 1980s, the Lotus Elan M100 series was built using a new aluminum architecture created mostly from aluminum sheets bonded together using a special epoxy resin and self-piercing rivets. Since then, aluminum and aluminum-intensive architectures (partly aluminum and partly light steel) have become the popular choice for lightweight bodies.

Mercedes-AMG has 50% higher transverse stiffness for the new SL body than for its Roadster GT and 40% more longitudinal stiffness and, compared to the previous model, 18% more torsional stiffness. We are constantly bombarded with details about the stiffness and strength of each new generation of bodywork by most manufacturers, but how is it done?

The materials of the SL are a blend of aluminum, steel, magnesium, and a composite of carbon and fiberglass assembled using a wide variety of methods. MIG (metallic inert gas) welding is one of them and a commonly used method for welding steel and aluminum. It consists of melting the pieces of metal to be assembled with an electric arc while continuously feeding a “filler” wire into the bath of molten metal as the weld progresses along the joint. The arc is wrapped in inert gas to prevent oxidation from weakening the weld, and a good weld looks like a well-sewn seam.

Robot laser welding is a more modern technique employed where greater precision is required. The components also use punch riveting (a self-piercing rivet that penetrates and drives into the two sheets of metal to be joined), blind riveting (also known as “pop” riveting) and taped seams, like the Elan but now commonly used throughout the aluminum construction industry. The final method used in the SL shell is drain hole bolting, which, like the punched rivet, is a self-piercing technique where a sharp bolt first pierces the metal and then self-taps, creating its own thread in an instant when screwed. in.

In addition to achieving stiffness, strength and a high degree of crash safety, a modern and advanced body like this must be designed with perfect closing lines measured in fractions of a millimeter. Although a far cry from its ancestor, the 1952 Mercedes SL, the goal was the same, except that it was then based on a rigid space frame that required the use of those iconic gullwing doors. In this sense, the SL is one of the best examples of how body technology has evolved over the years.

Aberdeen tests hydrogen