As we know, the next-generation SL will be an AMG exclusive that will sit alongside the GT Coupe and Four-door. Bearing a 2+2 layout, the brand’s halo moniker will be replacing the current GT Roadster range. As a teaser of what we can expect, an all-new bodyshell for the open-top performance car has been revealed by the brand.
Mercedes-AMG reveals that the architecture for the next-generation SL consists of the combination of an aluminium space frame with a self-supporting structure. It was created, as with the first SL in 1952, on a blank sheet of paper with not a single component being taken over from the preceding SL model or the AMG GT Roadster.
“The development team in our bodyshell design area was faced with an extremely appealing, but also challenging task. When we were commissioned to undertake the overall development of the new SL, we started from scratch, so to speak, without building on any existing structure. We can be justifiably proud of the result, which proves, once again, the high level of development competence in Affalterbach.
“On the one hand we have managed to reconcile the high package demands, while on the other we have been able to achieve excellent rigidity values in all areas in conjunction with a favourable weight, so providing the basis for agile driving dynamics and exceptional comfort.” says Jochen Hermann, Chief Technical Officer of Mercedes-AMG GmbH.
Mercedes-AMG states that the requirements for the bodyshell architecture of the next-generation SL were considerable. The specifications demanded a much more comprehensive scope of services than for the predecessor model series.
The basic layout with 2+2 seats and the potential to accommodate a wide range of drive systems had to be considered here. This made for 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 next-generation SL, the intelligent material composition of aluminium, steel, magnesium and fibre composites ensures the highest possible rigidity in conjunction with low weight. Optimised material cross-sections and sophisticated component shaping create space for the required comfort and safety features, the sophisticated technology and the soft-top.
Other targeted measures include aluminium 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 made out of a fibre composite material with a mixture of glass fibres and carbon, also demonstrate the engineers’ efforts to achieve the best possible, customised 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 aluminium components are used at the nodal points where forces come together or where functions are highly integrated such as areas 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 generation, the torsional stiffness of the bodyshell structure has been increased by 18 per cent. The transverse rigidity is 50 per cent higher than that of the AMG GT Roadster, while the longitudinal rigidity is 40 per cent higher. The likewise improved introduction rigidity for the chassis connection aims to ensure sporty driving performance with precise handling and high agility. The weight of the pure bodyshell without doors, bonnet and boot lid, as well as without add-on assembly parts, is around 270 kg.
The entire vehicle concept is geared towards the lowest possible centre 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. Examples of this are the connections between the front and rear sections and the passenger safety cell, with their high flexural strength and torque rigidity, systematically realised via force paths that are as low as possible.
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 quality standards were raised again here. Mercedes-AMG claims that the bodyshell architecture of the next-generation SL meets all internal crash requirements, which in many areas are significantly stricter than legal requirements.
Despite the extremely high quality requirements, Mercedes-AMG states that development for the next-generation SL’s new shell was done at a record-breaking pace with 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. The high quality of the software used in the digital development made it possible to give the go-ahead for the production of the series tools without a real prototype of the chassis. The so-called structural verification vehicle, which is of immense importance for passive accident safety, received internal top rating in the first real crash test.
Production of the next-generation SL will take place at the Bremen plant, where the preceding model already rolled off the production line.
