Crumple zone

The crumple zone is a structural feature mainly used in automobiles and recently incorporated into railcars.

Crumple zones are designed to absorb the energy from the impact during a traffic collision by controlled deformation. This energy is much greater than is commonly realized. A 2,000 kg (4,409 lb) car travelling at 60 km/h (37 mph) (16.7 m/s), before crashing into a thick concrete wall, is subject to the same impact force as a front-down drop from a height of 14.2 m (47 ft) crashing on to a solid concrete surface. Increasing that speed by 50% to 90 km/h (56 mph) (25 m/s) compares to a fall from 32 m (105 ft) - an increase of 125%. This is because the stored kinetic energy (E) is given by E = (1/2) mass × speed squared. It increases by the square of the impact velocity.

Typically, crumple zones are located in the front part of the vehicle, in order to absorb the impact of a head-on collision, though they may be found on other parts of the vehicle as well. According to a British Motor Insurance Repair Research Centre study of where on the vehicle impact damage occurs: 65% were front impacts, 25% rear impacts, 5% left side, and 5% right side. Some racing cars use aluminium, composite/carbon fibre honeycomb, or energy absorbing foam to form an impact attenuator that dissipates crash energy using a much smaller volume and lower weight than road car crumple zones. Impact attenuators have also been introduced on highway maintenance vehicles in some countries.

On September 10, 2009, the ABC News programs Good Morning America and World News showed a U.S. Insurance Institute for Highway Safety crash test of a 2009 Chevrolet Malibu in an offset head-on collision with a 1959 Chevrolet Bel Air sedan. It dramatically demonstrated the effectiveness of modern car safety design over 1950s design, particularly of rigid passenger safety cells and crumple zones.

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