How does the crumple zone reduce the impact of accidents?

During a car accident, the seatbelt is a primary restraint system, while the airbag is a supplemental restraint system. The airbag is meant to supplement the seatbelt; it is not an alternative to it. In the event of an accident, the seatbelt holds the body in place. Most of the reactive force is applied by the seatbelt. It also delays the time of impact by using pretensioners. The airbag, when used in tandem with the seatbelt, works more efficiently by extending the time of impact, which reduces the impulse force.

During an accident, crumple zones also play a crucial role. When a car crashes into an obstacle, it undergoes a huge deceleration. If the front part is made up of rigid structure, the opposite force from the obstacle stops the car immediately without any delay. The front part of older cars was made up of a rigid structure. The rigid structure transfers all the force to the driver without any delay. During a high impact crash, the engine and other metal parts may crash into the driver’s body, resulting in very high impulse force on the driver. This impact force can be reduced by crumple zones in addition to the seatbelt and airbag. The crumple zone is made up of a non-rigid, collapsible structure. When accidents occur, the front structure of the car crumples. This works like a cushion. It increases the delay in force travel, which increases the amount of time it takes for the driver’s body to hit the airbag. This reduces the maximum force on the driver’s body. Notably, the crumple zone is the only collapsible structure in a vehicle; the main body is rigid. The rigid body won’t collapse during an accident. Newer cars are also built with a crumple zone at the back end to improve passenger safety.

Fig:1a - Car crash without crumple zone
Fig:1a - Car crash without crumple zone
Fig:1b - Car with the crumple zone
Fig:1b - Car with the crumple zone

Other types of airbags

In an accident, the driver hitting the steering wheel is the most probable case. However, they may also hit the side window or other structures. To protect drivers and passengers from all possible impacts, modern cars are equipped with curtain airbags, side airbags, and knee airbags.

Fig: 2- Modern cars are equipped with knee airbag, side airbag, curtain airbag.
Fig: 2- Modern cars are equipped with knee airbag, side airbag, curtain airbag.

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