STUTTGART: The upcoming Mercedes-AMG SL will have a completely new vehicle architecture.
Developed by Mercedes-AMG, the lightweight composite aluminum chassis provides the basis for high comfort, precise driving dynamics, optimal packaging and sporty body proportions.
The first SL came out in 1952 and used a filigree space frame that combined low weight with the highest possible torsional rigidity. This construction was conceived for its original use in motorsport and further developed to provide the backbone for the later production SL model in coupe and roadster form.
The new roadster architecture consists of the combination of an aluminum space frame with a self-supporting structure. It was created - as with the first SL in 1952 - literally on a blank sheet of paper: not a single component was taken over from the preceding SL model or, for example, from the AMG GT Roadster.
The requirements for the bodyshell architecture of the new luxury roadster were considerable: the specifications demanded a much more comprehensive scope than for the predecessor model series. In particular, the basic layout with 2+2 seats and the potential to accommodate a wide range of drive systems were realized here for the first time in an SL, a task that presented the developers with completely new challenges in terms of complexity.
The aim was to present the Driving Performance characteristic of the brand with a focus on lateral and longitudinal dynamics, as well as to meet the high expectations in terms of comfort and safety.
In the new SL, the intelligent material composition of aluminum, steel, magnesium and fiber composites ensures the highest possible rigidity in conjunction with low weight. Optimized material cross-sections and sophisticated component shaping create space for the exceptional comfort and safety features, the sophisticated technology and the soft top. Other specific measures include aluminum thrust panels on the underbody and function-integrated struts at the front and rear.
The instrument panel support made of magnesium, along with part of the front module cover bridge in a fiber composite material with a mixture of glass fibers and carbon, also demonstrate the engineers' efforts to achieve the best possible, customized use of the most diverse materials.
This also applies to the windscreen frame made of high-strength, hot-formed tubular steel. This, in conjunction with a system behind the rear seats that extends at lightning speed if necessary, serves as rollover protection.
Cast aluminum components are used at the nodal points where forces come together or where functions are highly integrated, i.e. where large forces have to be transferred. Cast components have the advantage of enabling the specific discharge of forces, and make it possible to vary wall thicknesses locally according to the loads encountered.
Areas of greater rigidity can therefore be realised where required, for example at the chassis connections. Moreover, only the necessary wall thickness is provided at any point of the component, which saves weight in the areas subject to low forces.
Compared to the previous model series, the torsional stiffness of the bodyshell structure increased by 18 percent. The transverse rigidity is 50 percent higher than that of the AMG GT Roadster, while the longitudinal rigidity is 40 percent higher.
The improved introduction rigidity for the chassis connection ensures sporty driving performance with precise handling and high agility. The weight of the pure bodyshell without doors, hood and trunk lid, as well as without add-on assembly parts, is around 595 lbs.
The entire vehicle concept is designed towards the lowest possible center of gravity. This applies both to the low connection points for the powertrain and axles and to the lowest possible arrangement of the rigidity- relevant bodyshell structure.
Modern joining techniques such as MIG welding, laser welding, punch riveting, blind riveting, MIG soldering, glued seams or flow hole bolts as well as precise toolmaking raise the level of the bodyshell value appeal to the highest level. This applies equally to gap dimensions and to radii or joint courses. The new Mercedes-AMG bodyshell architecture meets all internal crash requirements, which in many areas are significantly stricter than legal requirements.
Despite the extremely high quality requirements, the development was implemented at a record-breaking pace: The pre-development was done in only three months. It took less than three years from the time the commission was given to a team of, initially, just six people to the release of the series.
Production of the new SL will take place at the Bremen plant later this year, where the preceding model rolled off the production line.
