Passive car safety

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The safety standards in top-class motor racing have improved at a breathtaking rate in recent years. The monocoque was invented by the legendary designer and Lotus team boss Colin Chapman, who inserted a riveted lightweight metal case instead of the classic tubular frame in his Lotus 25 in 1962. On the infinite safety scale, it has now reached a level that will be hard to surpass.

As Brian O'Rourke, specialist for composite materials with the WilliamsF1 Team says: "The monocoques used in Formula 1 are safer than they have ever been. Nonetheless, research and development in this field still continue because safety has the highest priority for the drivers."

Similar to the monocoque in Formula 1, the robust cell in passenger cars represents the heart of passive safety. It too should be affected as little as possible in the case of serious accidents. "It is crucial that the doors can still be opened easily after an accident," said Dr. Hartmuth Wolff from the Allianz Centre for Technology (AZT). "This stability is achieved with the selective use of high-strength steel in areas that require high rigidity: for example, in the pillars." However, rigidity alone is not enough in the area of the passenger cell. "For ideal occupant safety, the deformation behaviour, the rigidity of the cell and the function of the restraint systems and the seats must be coordinated precisely with each other," said Wolff.

In the Formula 1, the monocoque has become the most important component in the drivers' overall safety package since McLaren first sent cars with a carbon fibre safety cell onto the starting grid in 1984.

In spite of the high standard achieved, however, Formula 1's governing body, the Fédération Internationale de l'Automobile (FIA), never ceases in its efforts to improve safety in the sport even more. The crash tests which have been stipulated by the FIA since 1985 guarantee the load capacity of the monocoque and the crash structure, and they have become more and more stringent over the years.

Since 1997, it has been obligatory for the rear structure as well as the side crash structures and the roll-over bar to pass a crash test before every season. Here, again, the FIA is not satisfied with the standards already achieved and raised the level of the requirements a little higher before the 2006 season began by increasing the impact speed for the dynamic crash test of the rear area from 12 to 15 metres per second. That corresponds to an increase of 56 per cent in the impact energy on the rear crash structure, showing how much importance the FIA attaches to crash safety as reliable life insurance for the drivers.

The monocoques are made from carbon fibre, a composite material that is twice as strong as steel, but five times lighter. It consists of up to 12 layers of carbon fibre mats, in which each of the individual threads is five times thinner than a human hair. A honeycomb-shaped aluminium layer is inserted between these mats, which increases the rigidity of the monocoque even more. The whole shell is then heated under pressure in the autoclave, a giant oven. After two and a half hours, the shell is hardened, but still the baking procedure is repeated twice more.

As a result, the monocoques are strong enough to protect the drivers even in the most serious of accidents, like the one involving Giancarlo Fisichella at Silverstone in 1997. The evaluation of the black box showed that his Jordan slowed from 227km/h to zero in just 0.72 seconds, which corresponds mathematically to a fall from a height of 200 metres. Even so, the Italian only suffered a minor injury to his knee – thanks in part to the monocoque.

Allianz Safety Check: Albert Park Circuit
Mark Webber "On a road course such as Albert Park, we are inevitably relatively close to the walls. That can be dangerous both for us drivers and for the spectators. In recent years, the organisers have worked extremely hard to improve safety for the spectators – and they've succeeded. But they didn't forget the drivers, either. There are run-off zones at key points on the circuit. It wasn't easy to integrate them, but the people in charge have found an excellent solution."

Source: Allianz