Multi-material Design Lightweight construction succeeds with material mix
Frank Venier from Audi Lightweight Construction Centre started this year's "Automobil Industrie" Lightweight Summit with a keynote speech on the multi-material design of the new A8 and the fourth generation "Audi Space Frame".
Lightweight construction for tomorrow's mobility: With a keynote on OEM strategies and the example of the flagship Audi A8 project, the starting signal for the seventh "Automotive Industry" lightweight construction summit was given on 13 March. Specialist Frank Venier from Audi Lightweight Construction Centre spoke to almost 230 participants on lightweight construction technologies used in the flagship A8.
For the electrification of the power-train, the VW subsidiary focuses on weight reduction. "It is not sufficient to restrict our efforts on extending the range," Venier said at the beginning. The result should always be an overall system, in which points such as tire load ratings and driving license categories are considered.
The well-known slogan "The right material in the right place", coined by Audi's head of Lightweight Construction Heinrich Timm, still applies to future e-architecture. "Achieving the goal of economical lightweight construction is just as important," Venier noted. According to him, Audi now uses a complete range of materials. But why did Audi switch from the aluminium body to the multi-material mix, and what components has the company optimised in the new A8?
The fourth generation of the Audi Space Frame
Today, more than one million Audi models are based on the Audi Space Frame (ASF) design principle. The ASF, a framework consisting of aluminium components, extruded profiles, castings and aluminium sheets, is now being produced in its fourth generation – the internal designation is D5. The latest generation ASF has also been equipped with steel parts. This Venier explained, is , above all, with stricter requirements of the market and regulatory authorities, especially with regard to crash behavior and electrification. These, however, are not the only new demands: The internal requirements of Audi are also increasing, for instance, in the premium segment where maximum security plays an important role.
Audi relies on three systems to ensure the highest possible degree of crash safety:
- Multi-material mix
- Lightweight construction
- Active system
Only the combination of lightweight material construction and lightweight design ensure that forces are deflected properly to guarantee the desired crash behaviour. This combination is complemented by a "Predictive Safety Crash Side Assistance" system. If required, the active chassis can raise the vehicle slightly in the event of a crash. This improves the positive effects of the structures in the area of the rockers and the B-pillar. These three construction elements significantly improve the crash behaviour.
The Audi A8 consists of 29 different materials, including steel, extruded aluminium profiles, die-cast aluminium parts, sheet metal components and forged parts. A magnesium strut brace has been installed for the first time in the A8. Venier is also proud of the carbon fibre-reinforced rear wall – Compared to its predecessor, this CFR rear wall reduces the weight by 50%, whilst improving functionality, the expert noted.
Will lightweight construction be neglected in view of the mega trends of electric mobility, connectivity and automated driving? On the contrary, the new disciplines are even giving new impetus to lightweight construction. This is because they add to the existing demands placed on vehicle architecture, which can only be met with lightweight construction measures, for example, to meet load limits.
This article first appeared on www.automobil-industrie.vogel.de.