History and Development of Vehicle Chassis
Chevrolet introduced the Corvette with a fiberglass body. The Corvette wasn’t the first car to use fiberglass, but Chevrolet was the first big manufacturer who used this material in a series production. In 1957 Lotus succeeded In building a fiberglass monocle chassis for the Elite. It would remain the only car ever built with a complete fiberglass chassis, as the imprecision caused by the manufacturing process caused every car to be built with a loss. (See Fig. 3) Fig. 3: Lots Elite The main reason to use aluminum or fiberglass Instead of steel Is to save weight.
Fiber glass was common to be used for sports cars or kit cars that where produced in limited quantities. It is inexpensive to create moulds and fiberglass is easy to work with. However it is very difficult to achieve small tolerances in the fitting accuracy. The gaps of the panels are bigger and where small tolerances are needed O. E. Suspension or engine mountings) the required measurements can hardly be met. Engineers found the solution in using a rugged chassis onto which the fiber glass 1 OFF fiber glass body was glued to an Aluminum Frame. (See Fig. 4) In high volume production lines it is neither Fig. : People Speedster Frame economical nor practical to use fiberglass. In the late g’s the advancements in the automotive technology and the demands of the customers had an effect on the vehicle’s weight. Safety structures, comfort electronics, rust protection and an increase in size and engine capacity were the reason for the increase in mass. Cars not only become heavier over the years, they became uneconomical, since the traction resistance is 70 ‘ 80% affected by the weight of the vehicle, the handling suffered from it and the emissions rose. An example is the Audio 80 from 1972. When it was introduced it had a tare weight of 850 keg.
The body weighed 235 keg. Ten years later the bodyweight increased by 50 keg. The third series reached an overall mass of keg by 1986. Lightweight construction was the solution to these problems. The manufacturers could save the most mass by manipulating the body, because it constitutes 1/3 of the total weight. While a car in the g’s and g’s could be made of up to 75% steel, today’s cars only use 50%. In the next 15 ‘ 20 years it should be achievable to reach 45%. This lightweight construction not only saves weight, it also sees less raw material which saves the manufacturer money.
Some might think that steel might be a material of the past and that in the future we will only see cars made of aluminum, magnesium and glass fiber. Fact is that the steel industry is investing a lot in research and in developing new materials to improve their product. After all, steel is still cheaper to produce it is also a very stable and resistant material, has good deformational capability, can be manufactured with high fitting accuracy and it has good high power energy consumption abilities. A crash repair is easier to carry out on steel than on aluminum.
In order to repair an AY body, Audio uses a separate body shop especially designed to work on aluminum. Some manufacturers like Porch or strike a new path in using up to 60% high-tensile steel in their newest Subs: the Cayenne and Fig. 5: Porch Cayenne Torture. Porch even won the first place in the Steel Innovation Prize with their LULAS (Ultra Light Steel Auto Body) which was implemented in the Cayenne. (See Fig. In the future it is not a question of which material will be the best to build a 5) hashish or body, but which material will be used in order to achieve the best results regarding safety, economy and finish.
With “Tailored Blanks” the manufacturer can decide which part of the body should be strengthened. The new Joining technology like laser welding makes it possible to combine steel and aluminum in a new form of “Hybrid” chassis that allows the implementation of certain materials with pinpoint accuracy. BMW uses this technology in their newest BMW 5-Series (See Fig. 6). BMW redesigned the whole front end so that now it doesn’t weigh more than 47 keg and is only made of 1/3 of steel. This has not only the advantage of reducing the weight, but it also contributes positively to the front-rear weight distribution.