What lies beneath

The latest incarnation of the famed Audi Space Frame forms the foundation of the incredible new A8.

Audi has continued to refine its revolutionary Audi SPace Frame (ASF) to the point that it is considered an automotive world of art. The foundation of numerous Audi models, it lies at the heart of the new Audi A8.

17 July, 2017

Innovation is the foundation of Audi’s relentless pursuit of performance, design, safety and technological excellence and one of the brand’s game-changing innovations is hidden beneath the smooth skin of many Audi models – an automotive work of art that many do not even know exists.

In 1994 Audi stunned the automotive world with an aluminium-bodied A8 at the Frankfurt International Motorshow (pictured above). But it was what lay beneath the shining exterior that would change the face of automotive construction from that point forward. Dubbed the Audi Space Frame (ASF), the revolutionary vehicle was 40 percent lighter than previous models thanks to the Audi Space Frame construction, yet it was just as strong as a conventional steel design.

The inspiration for this revolutionary design philosophy came from an unexpected source, says Dr Bernd Mlekusch, Audi’s head of the Lightweight Design Centre in Neckarsulm, Germany.

“The decisive inspiration for the Audi Space Frame is found in nature. In a bee colony, for example, only the amount of material required to serve its function is used.”

In keeping with the principle of ‘the right material, in the right place, in the right amount’, the totally redeveloped Audi Space Frame for the new A8 is another lightweight masterpiece. Immensely rigid, it utilises four materials – aluminium, steel, magnesium and carbonfibre reinforced polymer for the first time – ushering in a new multi-material construction.

But long before the original A8 aluminium Audi Space Frame signalled a paradigm shift in automotive body design, Audi engineers had begun to steer away from using a single material and focus on many high-strength and lightweight materials, with each exhaustively tested, to determine their suitability for use.

The testing, knowledge, constant development and production of over one million ASF bodies has resulted in this latest version using carbonfibre-reinforced polymer at critical load-bearing points and the occupant cell rear panel, which itself contributes 33 percent of the Audi A8’s total torsional rigidity.

To reduce weight, increase strength and occupant protection, hot-formed high-strength steel components are used in the lower section of the front bulkhead, the side sills, the pillars between the doors that run from the floor to the roof and the front section of the roofline.

Aluminium makes up 58 percent of the new Audi A8 body including many of the outer panels, while the magnesium front brace, that straddles the engine, is secured by aluminium bolts to the front suspension towers and should a front impact occur, it channels the forces to three impact buffers in the front end.

Producing this latest Audi Space Frame body is a highly-complex process. World-first joining methods including roller hemming – joining metal panels by rolling the edges one over the other – grip punch riveting and remote laser welding of aluminium are all used.

The assembly begins with the welding of the lower assemblies such as the longitudinal members that form the backbone of the vehicle, then the front and rear assemblies are merged with the floor panels, front, middle and rear cabin pillars and the roof.

Pinpoint accuracy is required for the laser welding process and this is done in the geometry and framing stations of the conveyer-belt-driven assembly line.

Final installation of the driveline, suspension, brakes, wiring, electronics and interior takes place and throughout assembly, 20 zones with laser measuring equipment check the ASF body for dimensional accuracy. All the while spot testing of components, sub-assemblies and even complete bodies is conducted to ensure the highest quality standards are met.

Fittingly, the latest Audi Space Frame is produced in a new, purpose-built factory, made of 16,000 truck loads of concrete and 14,400 metric tonnes of steel; twice that of the Eiffel Tower.

It employs 500 staff and is equipped with 500 robots, 90 adhesive systems, 60 machines for self-tapping screws, 270 punch riveting systems and 90 resistance spot-welding tongs.

Although every A8 produced since 1994 is based on an Audi Space Frame, it is not the only model to benefit from this ground-breaking design technology.

The diminutive Audi A2 was the second recipient in 1999, the 1.2 litre diesel tipped the scales at a featherweight 825 kilograms.

Audi’s iconic compact coupé, the TT, was the first model to receive a multi-material ASF in 2006, while Audi’s sporting flagship, the 2007 R8 was built on a new ASF. The current Audi TT also uses an evolution of the ASF, combining high tensile thin steel with aluminium and in 2015 the weight of the R8 was further reduced by 200 kilograms in the second-generation model, by combining aluminium and carbonfibre – the front and rear body modules constructed of aluminium, as is the entire outer skin.

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What lies beneath

The latest incarnation of the famed Audi Space Frame forms the foundation of the incredible new A8.

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