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4T : Miscellaneous Features

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21 November 2012


It’s a very poorly kept secret that Audi is keen to maintain its strong leadership in the field of lightweight design. The ‘ultra’ branding Audi has applied to it and its key positioning within the brand’s motorsports efforts communicate this quite clearly. So too do behind-the-scenes lightweight production mules such as an aluminum chassis Audi A5 we test drove some time back or a carbon fiber lightened R8 chassis we spotted while touring Audi’s lightweight design center in Neckarsulm. Add to these one more car, what we’ve learned is to be termed the Audi TT evo plus.

To be honest, we’re not sure if we may have driven this car. The very same day we drove “The Beast”, that 2.5 TFSI-powered A5 manufactured in aluminum, Audi also let us drive a lightened Audi TT coupe painted in white. That was some time back though, and we’d nearly forgotten about it… at least until we read the story we’ve translated below via an Audi corporate publication that focused on technology. That story was about the TT evo plus, and the more you read the more you wovo plus nder if it’s not a harbinger of something coming soon. As “The Beast” was a chassis prototype for the quattro Concept, might the TT evo plus be a precursor to some third-generation TT concept car… or maybe even close to new parameters Audi hopes to set with the next generation production car?

We’re not entirely sure, but read on and you’ll learn as much as we have in this very interesting story. Begin translated feature.

 

As yet another example of Audi’s commitment to ‘ultra’ lightweight engineering, what you see here are chassis images of the Audi TT evo plus. And though it may share the same shape as the current Audi TT with its aluminum space frame including some steel segmentation, the chassis of the TT evo plus instead pushes the ultra-lightweight limits even further through construction from carbon fiber, aluminum and magnesium. Fully constructed, this TT coupe weighs less than 1,000 kilograms (2,204.6 lbs).

It doesn’t hurt that the car starts from an already strong position. Thanks to its Audi Space Frame made primarily of aluminum and some steel, the production car fitted with 2.0 TFSI already weighs just 1,280 kg (2,821.9 lbs).

“And with this new technology, the car is less than 1,000 kilograms,” states Peter Fromm, head of Audi design and development. “The TT evo plus is our latest spearhead into ultra lightweight design.”

Of course Audi isn’t new to lightweight design. The first production Audi Space Frame made of aluminum appeared in 1994 as the basis of the first-generation A8. Since then, the brand has continued to lead in this area.

The latest development for Audi in this area is the multi-material space frame, which combines different materials together, following Audi’s philosophy of “the right material at the right place for optimum performance.”

Just two copies of the Audi TT evo plus were created – a joint project between the Audi Lightweight Design Center and Audi Pre-Production (VSC) in Neckarsulm. “From the body alone, which in series production weighs just 206 kilograms (454.2 lbs), we have taken out another 43 kg (94.8 lbs),” states Thomas Milde, a development engineer at Audi.

“We have replaced steel components in the rear part of chassis with aluminum and in some cases carbon fiber reinforced plastic (CFRP) was used.

This material has been used on the roof, the center tunnel and the rear floor area, and carbon fiber parts such as the trunk lid, front fenders and doors bring another 38kg (83.8 lbs) in savings. CFRP is also used in the interior, including the lining of the doors, the side panels and the cover over the instrument cluster, shedding just over 13 kilograms (28.7 lbs).

“For us, the TT evo plus is very exciting because we are able to test these ultra lightweight design technologies that we want to introduce soon in series production,” states Heinz Hollerweger, Head of Overall Vehicle Development at Audi AG.

The rear portion of the CFRP segments also boasts a so-called OLAS (Oscillating Laminated Absorbing Structures) wave design  that will help disperse energy in a crash.

Many cables and covers are attached to an adhesive pin, a plastic layer provides a high strength connection with the CFRP when it is heated for a few seconds. A combination of adhesive and rivets is used to create a bond between the CFRP and aluminum.

In production of the TT evo plus, Audi was able to adopt an innovative new method of CFRP production technology. Just as Audi produces its DTM racecars, components are built around a foam core as hollow structures averaging only 1.3 mm width. Hinge mounts for the trunk lid, the corner reinforcement of the transmission tunnel and the plate in the upper floor are made of magnesium. This ultra light metal offers a weight savings of 15% over the already light aluminum.

And what advantage is gained from this re-engineering of the Audi TT? Project Manager Ralph Schünemann adds, “The TT evo plus can do 0-100 km/h (62 mph) in les than six seconds – 20% less thanks to the lightweight construction and also lightening the engine. We made it lighter by 25 kilograms (55.1 lbs) around the block, at the crankshaft, the flywheel and via the ancillaries. And the exhaust system is made of ultra lightweight titanium that saves another 14 kilograms (30.9 lbs) of weight.

Schünemann is looking forward to the day when he can drive the TT evo plus on the track for the first time. “The handling will be very sporty. We use aluminum dampers and new springs made of fiberglass reinforced plastic, which will soon go into production.  At the front we use a lightweight brake system with aluminum. The stabilizer is made of CFRP, along with the brakes and that brings a savings of 13 kilograms (28.7 lbs). Also, the forged 18-inch wheels of a special ultra Design weigh just 6.4 kg (14.1 lbs) each.

At the front, the car already utilizes the technology of the next TT – most of the units come from the Modular Transverse Matrix (MQB). The engine is installed at an anagle towards the rear, the front axle and steering has moved seven inches forward. Schünemann comments, “We have taken away a lot of weight from the ends of the car and moved it to its center, thus the TT evo plus is even more agile. The starter battery located in the interior, for example, is positioned in front of the rear axle and constructed with lithium-ion technology. It is much smaller than a lead battery and weights just under four pounds.”

“The TT evo plus is a dynamic car, but the driver does not go without… except for the absence of a rear seat. In its place we can fit a reinforcing bar with a luggage net, “says Jochen Uhl, construction manager and dsign coordinator for special vehicles at the VSC in Neckarsulm.

Uhl’s team paints the body of the finished car in an innocent white with an interior in fine style by Audi. Deep shiny carbon fiber contrasts with black Alcantara upholstery, with the back of the lightweight racing seats also made of carbon fiber. Air conditioning and electrically operated windows are all retained.

The technology puzzle in place for the VSC team comprises several thousand parts.  From major components such as engine and transmission, to the smallest screws and plugs… the assembly requires precision and expertise. How do you get the new engine control unit from the MQB to communicate error-free with the electronics of today’s TT? Are the points of the new clips on the right side of the trim set? Does the default program exactly correspond to the weight of the rear axle?

“We put around 500 hours of work into the assembly,” calculates Uhl, “In the production of the body there are 800 more hours. All of that material has to come at a price, and it is done quickly. Some panels are knocked over forms by hand, with a craftsmanship that our colleagues in the VSC have mastered to perfection.”

“When the TT evo plus is ready, it will be worth every penny. Peter Fromm, head of structure development at Audi AG, outlines the importance of the support for technology in just two sentences. “The weight of less than 1,000 pounds, a statement of which we are produ, because it is the leadership Audi’s lightweight engineering demonstrates. The ultra-lightweight design principle means that we can always rewrite the limits of what is possible and, thanks to our strong team, we move a little further ahead every time.”

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