Costruire auto leggere è da lungo tempo una delle principali priorità di Audi: è uno dei pilastri della marca. Come pioniere del corpo in alluminio autoportante, Audi è leader mondiale nel campo della Lightweight. Innovazioni future faranno in modo che il marchio possa continuare a invertire la spirale di peso e costruire ogni nuovo modello Audi più leggero di quello che sostituisce.
Lightweight Design – a core competence of Audi
Light cars in large volumes – an Audi core competence
Lightweight construction has long been a top priority at Audi; it is one of the pillars of the brand. As the pioneer of the self-supporting aluminum body, Audi is the worldwide leader in the field of lightweight construction. Future innovations will ensure that the brand can continue to reverse the weight spiral. Each new Audi model will be lighter than the one it replaces.
Audi’s lightweight construction approach is a philosophy embraced by every development engineer. It begins with the body and emanates outward to include every area of technology in the complete vehicle, from the engine to the wiring harness. And it is not just the aluminum bodies featuring the Audi Space Frame (ASF) design that are unusually light. A number of volume models with steel bodies also set the standard in their respective class.
When it introduced the first A8 in 1994, Audi had not only developed the ASF design and put it into series production, it had also developed all of the steps required for its production. This integrated approach was what made this breakthrough possible. Audi gradually expanded its competences, adding numerous high-tech fabrication processes, in particular.
The brand takes a holistic and sustainable approach to this field of technology that encompasses the entire development and production chain. For Audi, lightweight construction not only means material engineering, it also means full competence in process technology, the development of new joining technologies and the validation of service and repair options.
Lightweight construction in large volumes is an Audi core competence. Since 1994, the company has continuously produced vehicles with ASF bodies. The number now totals 550.000, far more than any other manufacturer in the world. In the current model lineup, the A8 luxury sedan and the R8 high-performance sports car represent the ASF principle in its purest form. The body of the TT compact sports car is a hybrid aluminum and steel construction, and the A7 Sportback and the new A6 have steel bodies with a large fraction of aluminum.
The evolution of the Audi Space Frame
Audi is now taking the ASF principle to the next level – the Multimaterial Space Frame. This combines aluminum, steel and fiber-reinforced plastics. While still a space frame construction, this involves the use of some new joining technologies.
What makes the space frame principle so impressively elegant from a technical perspective is that separates the tasks of the various components of the body. The extruded sections bridge spaces, the cast nodes connect the components, the aluminum panels close off the spaces and lend rigidity to the framework. The space frame principle assigns a specific task to each material and each component. This gives the development engineers much more freedom than the traditional monocoque sheet metal design.
Audi is convinced that the Multimaterial Space Frame is the right approach for building vehicles in high volumes. Compared to a CFRP body, it is just as good, if not better with respect to weight, and it offers major advantages, not the least of which are a better overall energy balance and the lower costs.
Wide-ranging materials competence
At Audi, lightweight construction does not mean the rigid fixation on a single material, but rather working intelligently and flexibly with diverse materials. Our motto is, “The right material at the right place for optimal function.”
The objective is to achieve the best performance while using the least amount of material possible, but using it at the right place. Just like in nature, where material is not wasted, either. The engineers have developed wide-ranging expertise in all of the relevant fields of technology. Every material, whether steel, aluminum or fiber-reinforced plastic, is repeatedly reviewed for it suitability for the intended purpose, and the Audi experts are intimately familiar with their potential and weaknesses.
The materials are in competition with one another, and Audi can use any and all advancements to its direct advantage. With aluminum, for instance, new high-strength alloys and further refined component structures will result in significant progress very soon. In the medium term, CFRP components will make the structure of the ASF even stronger, lighter and safer. Audi can use precise simulations to accurately compute the crash properties of this material.
The Audi Lightweight Design Center
The primary source of this broad-based competence is the Audi Lightweight Design Center. Roughly 180 specialists work at the facility. The ALDC is the company’s spearhead in lightweight construction. The lessons learned here have so far provided the basis for numerous patents, for the honor of European Inventor of the Year 2008 by the European Patent Office, and for four wins in the Euro Car Body Award, the world’s most important competition in car body design.
Some 50 experts in the FRP Technical Center are now focusing their efforts on fiber-reinforced plastics. Audi is engaged in a lively technology transfer with its sister brand Lamborghini in the fields of CFRP and aluminum, with both sides continuously gaining new insights.
A century of lightweight construction
Lightweight construction has a long tradition at Audi and its predecessor companies. In 1913, NSU built the Type 8/24, a model having a body made entirely of aluminum. Ten years later, the Audi Type K wore an experimental streamlined skin of this same material.
In the 1930s, specialists from the Racing department of Auto Union shaped aluminum panels by hand, from which the bodies and streamlining panels for their spectacular race cars and land speed record cars were built. The 1936 Auto Union Type C tipped the scales at just 825 kilograms (1,327.71 lb) ready to race. With its V16 supercharged engine producing a good 280 kW (520 hp), it had a power-to-weight ratio very close to that of a modern Le Mans sports prototype.
Audi continues to drive progress on the racetrack today. The rally and circuit race cars in the years around 1990 included many plastic parts in and on the body. Some of them were already using cardan shafts of carbon fiber composites at that time. This was already a standard feature on the Audi 90 quattro. Today the Audi R18 and the A4 DTM serve as rolling labs for working with CFRP.
Coming to production vehicles, the first Audi A8 caused quite a stir upon its debut in 1994. With its ASF body, the A8 incited a minor revolution in the rather conservative steel and castings industry and placed suppliers under tremendous pressure. Since then, the strength of high-strength steels has increased by a factor of 5, and foundries have made significant gains in quality standards. The Audi ASF principle has benefited not just the brand’s customers, but the entire industry.
Lightweight construction will again play a crucial role in electric mobility of the future. New components such as the traction battery contribute a substantial amount of additional weight, and intelligent lightweight construction can compensate for this in many areas. The engineers in Neckarsulm are already working to develop entirely new solutions for the bodies of future electric vehicles.
Audi lightweight construction – the reversal of the weight spiral
Throughout almost the entire automobile industry, vehicles are getting steadily heavier from generation to generation. This has been the case for many years now. Not at Audi, however. The brand with the four rings is reversing the weight spiral with its systematic strategy of lightweight construction. The second generation of the TT compact sports car tips the scales up to 90 kilograms (44.09 and 198.42 lb) less than its predecessor. With the new A6 currently being launched, this difference can be as much as 80 kilograms (176.37 lb), depending on the model. Each new Audi model will continue to be lighter than its predecessor.
The lightweight construction principle practiced by Audi conserves resources, lowers fuel consumption and thus enhances economy. Depending on the engine, the new A6 consumes as much as 21 percent less fuel than its predecessor. Lightweight construction accounts for roughly one-fifth of this progress. Generally speaking, shaving 100 kilograms (220.46 lb) of weight reduces fuel consumption by between 0.3 and 0.5 liters per 100 km.
At Audi, lightweight construction begins with the body, which brings with it an array of secondary effects throughout the rest of the car. A lower body weight enables the use of more compact brakes, a smaller engine, a correspondingly trim exhaust system and a smaller fuel tank. The individual components also harbor a lot of potential for saving weight. Lightweight gas springs are sufficient for a lighter aluminum rear hatch, for example.
Lightweight construction also offers decisive advantages with respect to sportiness, driving safety and comfort. A car weighing 1,200 kilograms (2,645.55 lb) reaches the 100 km/h (62.14 mph) mark from a standing start 6 meters (39.37 ft) sooner than a vehicle weighing 1,300 kilograms (2,866.01 lb). The reduction of so-called rotating masses with their moments of inertia has a particularly strong effect on acceleration.
A lower vehicle mass also has many positive effects on braking. Stopping distance is shorter and less heat is generated. The lighter a car is, the less kinetic energy it develops and the less of this energy needs to be converted into deformation in the event of a crash. In the event of a collision, less load is also exerted on the other vehicle involved.
One particularly interesting field of technology is lightweight construction in the chassis. The reduction of the unsprung masses at the wheels makes it possible, for example, to build lighter suspension components.
