What is a Crumple Zone?

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Also called the “crash zone” or “crush zone”, a crumple zone is an area in a vehicle’s design that folds in a specific manner to prevent the car’s occupants from being injured. The level of impact is reduced, lessening the chance that the passengers will be injured in a crash. Examples of crumple zone designs include segments of the frame that are engineered to bend or collapse in specific ways, the metal that will absorb enough energy to prevent the passengers from feeling the force of a crash. On high-performance cars, a honeycomb design is usually implemented and is ordinarily rigid but will decompress in a collision.

History of the Crumple Zone

Early vehicles were very resistant to bending in crashes, leading to the interior of the car and its occupants to endure the force of the crash. In the 1950s, manufacturer Mercedes-Benz began incorporating the crumple zone into their vehicles, starting with the Ponton Mercedes (model series W120). In 1967, the Mercedes Heckflosse a.k.a. Fintail became the first production car with crumple zones.

crumple zone car
A 1950s Mercedes Ponton. This was the first model to implement crumple zones.

How Crumple Zones Work

Crumple zones have two goals:

  1. To distribute the initial force of a crash so that the impact is lessened for passengers and so that their momentum is affected.
  2. To reduce deceleration.

It all comes down to physics. Isaac Newton’s First Law of Physics states that an object in motion will remain in motion unless an outside force acts upon it. So if a car formerly in motion suddenly stops, the bodies in it will stay in motion at the same speed until a barrier stops them. Crumple zones are used to transfer energy during a crash in such a way that the impact is not as powerful and the likelihood of passenger injury or death is decreased significantly. Crumple zones at the front and back of a vehicle are designed for destruction, “taking the heat” of the crash.

Newton’s Second Law of Physics comes into play for the second goal of crumple zones. According to the law, force equals mass times acceleration. So if the rate of acceleration is decreased (i.e. a vehicle’s braking time increases), so does the force of impact during a crash. Crash zones allow for a car to take longer to come to a complete stop.

Think about the difference between the times you have made a sudden stop at a traffic light or maybe a sudden change on the road like a pedestrian crossing in the middle of a road, and the times you have made a slower, gradual stop, fully able to anticipate the need to stop at a yellow traffic light. Now think about the difference in your body’s movement in reaction to these two kinds of stops: the feeling that your body was still propelling forward with the first stop, possibly even hitting your steering wheel or coming close, and your body remains in its usual position in the second stop. Crumple zones make it so that in the case of an accident, the force of that collision would decrease the chances of your body propelling forward.

The Future of Crumple Zones

Safety regulations have expanded, and crash tests have been added, influencing how cars are designed. As these trends in car making continue to evolve, crumple zones continue to be helpful and relevant in the goal of ensuring car safety. As automakers continue to conduct crash tests and evaluate real-world accident data, they will continue to develop vehicle frames that are designed specifically to protect the occupants in the event of a collision.

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