Die grössten Probleme hatte Ducati anscheinend mit der Schweisstechnik...
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A Brief History Of Motorcycle Chassis Design
Before we look at carbon fiber, a quick word on motorcycle chassis. Once upon a time, a frame was just some tubing that held the engine in place and connected the steering head to the swingarm. As tires improved and engine outputs increased, the forces involved in braking and accelerating started to overwhelm the tubular steel chassis, and frame builders started to make their frames stiffer. In the 1990s, chassis builders started to encounter the opposite problem: as their frames got stiffer and stiffer, the bike started chattering and vibrating, making handling terrible, especially when leaned over, when the suspension of a bike ceases to work, being in the wrong plane. And so the concept of flex was introduced, adding sufficient flexibility to allow the bike to absorb some of the bumps while leaned over, but still stiff enough to keep the chassis stable in a straight line and under braking. Since the late 1990s, and especially since the four-stroke era began, a huge amount of work has gone into engineering in exactly enough flexibility in specific areas, while retaining the stiffness in the planes where it is needed.
As tuneable flexibility has become increasingly important, the attractiveness of alternatives to aluminium has also grown. Traditional aluminium has the benefit of being light and easy to work with, but as MotoGP chassis designers push the limits, they also run into a few limitations. Engineering in flex is a matter of designing chassis elements with a specific thickness and shape, but the underlying properties of aluminium mean that at some point, achieving the precise amount of flexibility required means sacrifices strength. The way to get around this problem is by making elements longer, allowing a mass (usually, the mass of the engine) to use the greater leverage provided by a longer element (such as an engine spar connecting the engine to the main chassis beam) to provide the flexibility without sacrificing rigidity.
When the rest of the world switched from perimeter steel tube frames to aluminium twin spar frames, Ducati took a different but still ingenious approach. Instead of wrapping the engine in aluminium box section, Ducati welded up short sections of light steel tubing to create a trellis frame. The advantages were that the chassis was relatively easy to tune, by changing the diameter and position of the individual tubing sections and redistributing the load and the flexibility, and Ducati persevered with the design for six years until they dropped it in favor of carbon fiber.
The downside to the trellis frame is that the trellis - a series of joined triangles - limited the amount of space available for the airbox. All those short, straight tubes meant the airbox had to be shoehorned in, restricting the airbox in both size and shape. Furthermore, the disadvantage of having the frame constructed from twenty or so short sections of steel tubing is that those twenty tubes require forty welds to join them all. Getting weld strength to a precise tolerance is a very tricky art at best, and the more there are, the more chance of variation. While still at Ducati, Casey Stoner said that even when he had identical setups on his two Desmosedicis, they would never feel exactly the same. Paddock rumor suggests that variation in stiffness between two supposedly identical steel trellis chassis could be large - as much as 15% - due in part to the problems of reproducing so many welds and so many parts to completely identical specifications.
Hier noch der Link zum vollständigen Artikel
The Trouble With The Ducati Desmosedici: An Exhaustive Analysis