Higher rigidity, greater sporting character

Body rigidity is a decisive factor when designing a good sports car: the aim is clearly to transmit the output from a powerful engine efficiently to the road in the form of precise handling and roadholding. This in turn means choosing the most suitable running-gear settings, and for these to have their maximum effect - the body itself must act as an extremely rigid "backbone".

The running gear needs this substantial body structure against which to "react": even in the most severe conditions, there must be no distortion. Body movements generate oscillation, which can conflict with movements of the suspension and have an adverse effect on the car's road behaviour.

Modern techniques, from computer simulation to laser welding, enable body rigidity values to be achieved which would previously have been considered impossible. It is a particular challenge, however, to do this while keeping the weight as low as possible. For the Audi TT Coupé the development engineers were able to draw on more than 10 years of experience with the finite-element method of computer-aided strength calculation. In addition, they utilised weight-saving construction principles which also extend back for several model generations, notably those adopted on the Audi A8.

Aluminium is a material used to reduce the weight of the Audi TT Coupé in many areas. The engine compartment lid, for instance, is made from this material, as it is on the Audi A6.

The Audi TT Coupé achieves the high torsional rigidity needed for a sports car with roof frame and door sill elements of generous cross-section - up to a third larger than in comparable saloon cars, though in practice very little heavier.

The dimensions and patterns of the elements which connect the body sections together are also of decisive importance. On the Audi TT Coupé, for instance, the door sills are anchored to the front and rear roof posts and the rear side members by means of large-area metal sections in the side panel frames.

The struts to the left and right of the centre console inside the car create an authentic "sports-car look", but have a clearly defined function to fulfil as well: they strengthen the entire area between the dash panel and the floor pan, and in doing so significantly reduce steering wheel shake.

As well as "local" measures such as these, high levels of torsional and bending strength are essential if vibration and body shake are to be minimised. The Audi TT Coupé achieves outstanding results in this area. Its static torsional rigidity is 19,000 Nm per degree of angle and the first intrinsic bending frequency is as high as 50 Hz. This latter value in particular is reliable proof of a genuinely rigid bodyshell with a "clean" vibration pattern, and therefore a guarantee of the safe, comfortable ride that is so typical of the TT.

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