BMW Engineering Lighter, Safer Electric Cars
Mark Webber has a lot to thank tiny strands of carbon for. When his Formula 1 car cartwheeled in a spectacular 306kph (190mph) crash at the recent Valencia Grand Prix, what helped him to escape unscathed was the immensely strong carbon-fibre “tub” that racing drivers now sit in. Carbon fibre is an expensive alternative to making things in steel or aluminium, but besides being extremely strong it is also very light. It is found in high-performance parts, like aircraft wings, bits of supercars and the frames of pricey mountain bikes. But if work by Germany’s BMW proves successful, it could also become the material of choice to mass-produce electric cars.
The Bavarian carmaker plans to launch a new plug-in electric car in 2013. It will be one of the first designed from scratch to use an electric motor rather than being converted from an existing model. Reducing the weight of this four-seater car, known as the Megacity concept, will be crucial to improving its performance and range. So BMW is planning to use no steel at all. The Megacity will be built as two modules: an aluminium chassis will contain the electric drive-system and battery, and a body made almost entirely of carbon fibre will be fitted onto it.
Carbon fibre is 30% lighter than aluminium and 50% lighter than steel. The fibres are extremely tear-resistant. When woven into a lattice structure and impregnated with resin they can produce a part that is stronger than steel. The trouble is the process is labour-intensive and slow, not least because components may have to be cured for hours under pressure in massive ovens called autoclaves. For carmakers, used to stamping out steel body-parts in a few seconds, this has ruled out carbon fibre for high-volume production. BMW, however, aims to change that.
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