Audi is writing a new chapter in its successful history of lightweight design. For the coming generation of the Audi A8, an intelligent mix of four materials will be used in the body structure for the first time – more than in any of the brand’s previous production models. The luxury sedan is thus once again rightfully claiming its role as an innovation driver in automotive lightweight design. A tradition that dates back to the year 1994, when the A8 with its aluminum unitary body in Audi Space Frame (ASF) design caused quite a sensation.
Audi long ago abandoned the obsession with using a single material, however. In modern lightweight design the focus is on intelligent and flexible use of a wide variety of materials – in keeping with the principle “the right material in the right place in the right amount”. Each material is tested to determine its suitability for its intended purpose, and the Audi experts possess an in-depth understanding of its potential and the advantages it offers. All advances in the “competition of materials” can be put to direct use by the company in its new models.
This constantly growing wealth of know-how is particularly evident in the coming generation of the Audi A8. The luxury sedan’s load-bearing structure combines four different lightweight design materials – a mix of aluminum, steel, magnesium and carbon fiber-reinforced polymer (CFRP). It has thus ushered in a new stage in multi-material construction that provides direct benefits to the customer – and not only in terms of weight. As for torsional rigidity – the critical parameter for precise handling and pleasing acoustics – the new Audi A8 surpasses its outstanding predecessor’s rigidity value by up to 24 percent.
Ever since the first generation of the Audi A8, the Audi Space Frame (ASF) has been generating strong momentum for lightweight design in automobiles. Since then the premium brand has built more than one million production cars in accordance with this design principle, and it has been consistently building upon its know-how in the use of materials and joining techniques. The result is bodies whose low weight and high rigidity form the basis for greater performance, efficiency and safety.
Following nature’s example – the Audi Space Frame design principle
“The decisive inspiration for the Audi Space Frame is found in nature,” said Dr. Bernd Mlekusch, Head of the Audi Lightweight Design Center (ALC) in Neckarsulm. “In a bee colony, for example, only the amount of material required to serve its function is used.” In the early 1990s the lightweight design experts at Audi drew from this insight when they were designing the structure of the ASF, which consisted of extruded profiles and die-castings. Sheet panels including the roof skin, floor and side panels were incorporated into this lattice to boost rigidity and serve a load-bearing function. The individual components exhibit various shapes and cross-sections depending on their task.
The aluminum ASF body of the first A8 generation made the car more than 40 percent lighter than had been possible with a conventional steel design. That kicked off a development spiral among the steel producers in the competition of materials. Since then, the strength of new high-strength steels has increased by a factor of five.
And of course the ASF aluminum technologies didn’t remain static. They were always being further developed in the direction of new material grades and joining technologies, which are available on the market today. This is why the Audi lightweight design offensive has benefited not only the brand’s own customers, but also the entire automobile industry.
The Audi Lightweight Design Center
The great expertise in body development that Audi has at its disposal has all been brought together in one location – the Audi Lightweight Design Center, which was established in 1994. What has been learned here has provided the basis for hundreds of patents, for being honored as 2008 European Inventor of the Year by the European Patent Office, and for winning the Euro Car Body Award four times, the leading competition in the field of car body manufacturing.
Among the roughly 200 specialists at the ALC, about 25 experts are concentrating on fiber-reinforced polymers (FRP). The FRP Technical Center covers the development process in its entirety. The center focuses on not only materials technology, but also the full spectrum of expertise in component processes technology, development of new joining technologies, quality assurance and development of service and repair solutions.
The equipment, data and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.