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Why You Want Your Car To Crumple

3 minute read

One of the most effective innovations in automobile safety, the crumple zone is the area of a vehicle that is purposely designed to deform and crumple in a collision. In most modern-day vehicles, this is built into the front end of a car to allow it to absorb the impact from head-on collisions.

The ability for structural areas of a car (determined by the use of various strength metals in specific areas) to deform and redistribute the kinetic energy released on impact, saves countless lives every year. While the image of an accordion-crumpled car may not seem pretty, the more your car crumples, the better.

How does the crumple zone work?

The crumple zone works primarily in two ways. Firstly, it redistributes the forces involved in a crash to prevent it from reaching the occupant and passenger cabin at full force. Secondly, it slows down the collision time and increases the time it takes for passengers to undergo deceleration, thereby reducing forces on the body and decreasing the severity of injuries.

In an earlier blog article, we looked at the physics of a crash and what happens when two objects hit each other. In simplified summary, according to Newton’s Law:

When two objects interact, they apply forces to each other of equal magnitude and opposite directions.

While it is inevitable that a person in a car will still experience some absorption of this force, what the crumple zone does in conjunction with side impact protection and rigid passenger cells, is work as a buffer around the perimeter of a vehicle. By crumpling in a controlled and predictable manner in front of and behind the passenger compartment, structural areas of the body are sacrificed so that minimal impact is applied to vehicle occupants. This is why in specific head-on crashes, it is common to see a severely damaged car hood and front, but a stable and less-affected passenger cage.

What were cars like before the crumple zone?

Car bodies were first designed to be rigid without regard for occupant safety. While this was unintentional, what this rigidity would mean – in conjunction with a lack of other safety features – was that in a collision:

  • There would be no redistribution of kinetic energy,
  • The vehicle would stop more suddenly and potentially rebound, and
  • The rigid body would transmit higher amounts of energy to its occupants, who would therefore undergo more forceful collisions with internal car structures and suffer greater damage to internal organs as a result

Take the scenario where a car travels at X speed before crashing head-on, into a solid brick wall, in a car with no crumple zone. Because there is no buffered area available to absorb the shock of the impact and move forces away from the passenger compartment, all components of the car (including the passenger cabin) would be subject to absorbing the full force in a crash. In cases where the engine was built to sit at the front of the car, with nothing to stop it from moving, the engine would also be pushed into the passenger compartment, crushing them in the crash.

The Invention of the Crumple Zone:

In 1951, Mercedes-Benz engineer Béla Barényi, patented the crumple zone. Focusing on vehicle rigidity, Barényi realised it was safer for occupants to be in a vehicle that dissipated most of the energy from a crash before reaching the passenger cabin. At the time, this was considered counterintuitive thinking to his counterparts who believed, that strong, rigid vehicles are what would keep an occupant safe.1

While reinforced strength and extra rigidity were required in certain areas of the car, for instance, in the passenger cabin, this was not the case for the front and rear end of vehicles. Barényi’s patent led to the creation of a new type of car body – one that had a rigid cabin yet a collapsible front end. When involved in a crash, this design crumpled and folded to allow energy to dissipate along the body in milliseconds, to preserve the integrity of the space the passengers were in.

Car Crash Test Mercedes-Benz

In 1959, the Mercedes-Benz 220 sedan was released using Barényi’s vehicle body design. The car, however, featured not only the first crumple zone in the automotive world but also safety door latches that kept occupants from being ejected in a crash, a steering column hub that would not impale a driver upon collision and a padded dash that was situated lower in the car to avoid it being hit by passengers. These were just a few of the more than 2500 patents Barényi produced concerning aspects of car safety.2,3

Since its invention, the materials and structures used in the manufacturing of vehicle crumple zones have been continuously refined, but the engineering behind Barényi’s crumple zone remains and continues to save countless lives.

Sources: (1) (2) (3) (4 – Images)

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