Light yet safe contender for city streets: Carbon fiber lightweight design for electric car

January 30, 2013
Light yet safe contender for city streets
First a whirring sound, then the crunch of tires on the road. Things are pretty quiet when the Visio.M engineers take their prototype e-car for a spin. Credit: Credit: A. Heddergott / S. Rauchbart / TUM

Can an electric vehicle be extremely light and safe at the same time? Researchers working on the Visio.M project aim to show that the answer is yes. Scientists as well as engineers from Germany's leading technology companies have teamed up to develop a Visionary Mobility concept car to meet tomorrow's electromobility needs. They have chosen a sturdy monocoque body, state-of-the-art carbon fiber materials and a lightweight engine and transmission system.

Up to now, it has been a case of "either/or." On the one hand, we have the typical ultra-compact, lightweight electric car, where designers have had to compromise on safety. With larger e-cars on the other hand, the heavier frames and crumple zones come at the expense of battery range. But now researchers as well as engineers from some of Germany's top technology firms are looking to create the best of both worlds. The aim of the Visio.M project is to develop a mobility concept for an efficient electric vehicle, making the design as light as possible while still delivering the best possible safety protection.

The Visio.M engineers decided in favor of an innovative monocoque body structure. Typically used in racing cars, a monocoque chassis combined with enables good stability while keeping overall weight to a minimum.

Innovative materials

The developers are also breaking new ground in their choice of ultra-lightweight materials for the structure: The passenger compartment will be made of -reinforced plastic. of this type are already used in the manufacture of aircraft and luxury sports cars. The downside is that they are extremely complex to produce and expensive as a result. So the Visio.M engineers intend to investigate the feasibility of carbon in ultra-compact cars suitable for series production.

For the drive system, too, the Visio.M developers are looking to keep weight to an absolute minimum. The e-car they are designing will have an efficient and compact asynchronous electric engine. The transmission system will incorporate very light gears resting on hollow shafts. This would make the gears up to 15 percent lighter than conventional designs.

Safety first

The lightweight design innovations may be impressive, but driver and passenger safety is still the number one priority of the Visio.M project. The sturdy carbon fiber structure will incorporate various dedicated active and passive features addressing the specific safety challenges of an ultra-compact electric car. The ideas being investigated include specially adapted seatbelts as well as other innovative concepts to minimize potential injuries in the event of an accident. By the end of the project, the researchers hope that they will have achieved the maximum possible level of safety.

A research prototype vehicle has already passed some initial chassis tests. The Electronic Stability Program, i.e., the anti-lock braking system and the torque vectoring system, have been put through their paces at a test site near Munich – marking another successful step in the move to develop a safe electric vehicle.

Explore further: Electric mass mobility for urban environments

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1 / 5 (1) Jan 30, 2013
Is there any way to repair the carbon fiber monocoque with normal tools available to garages, or do you have to toss the entire car after a fender-bender because it's essentially non-repairable?

1 / 5 (1) Jan 31, 2013
I once saw a race car hit the wall and come to a complete stop. They pulled the driver out and carted him off in an ambulance. Another guy hopped in the car and drove it off the track. Stiffening a vehicle past the point of insuring it does not crush it's occupants only increases the g-forces they will experience in a crash.

The occupants of an 1800lb car struck by a 6000lb pickup going 60mph will fair much worse than the occupants of a 4200lb car everything else being equal.
not rated yet Jan 31, 2013
We are all sure that it will be a primary design goal for American Car manufacturers.

"do you have to toss the entire car after a fender-bender because it's essentially non-repairable?" - Eikka

Perhaps Government will be smart enough to produce crash standards that will not permit the Auto Makers from engineering more crap cars.
not rated yet Jan 31, 2013
Is there any way to repair the carbon fiber monocoque with normal tools available to garages, or do you have to toss the entire car after a fender-bender because it's essentially non-repairable?

I presume the care will have separate body panels much like they do now, so prang a wing, replace it in the same way they currently do.

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