Crumple zones are designed to “crumple”, or fold, when the vehicle encounters an accident.
They are meant to achieve two things: reduce the initial impact and redirect the impact force instead of sending it into the passenger cabin.
More specifically, the crumple zones are designed to absorb the energy during the accident by deforming instead of letting the whole car take the force of the impact.
Where are the crumple zones in a car?
Also known as crush zones, the crumple zones are located in the front and rear of the car.
In the middle is the ‘safety cell’ where the passengers and driver sit.
It is this ‘safety cell’ that is supposed to protect the occupants of the car, while the front and rear crumple zones take the brunt of the impact.
The cell itself is made out of stronger materials than the crumple zones, enabling it to survive a collision and protect the occupants.
In mathematical terms, if you remember your secondary school physics, Force = Mass x Acceleration.
In that equation, the car already has a fixed mass, which leaves Acceleration as the other component which we can lessen in order to reduce the final impact (Force).
Even slowing the car down by a fraction can make a huge difference in the impact energy.
When the crumple zones have decelerated the car as much as they can, impact mitigators like seatbelts and airbags take over to lessen the force the occupants feel.
In motor racing
If you see a Formula 1 car or NASCAR stock car completely disintegrating on impact, that’s a good thing.
The more the car disintegrates, the more energy is dissipated, which means the driver is spared the brunt of it all.
If all the force of the accident is spent on destroying the car, the driver will feel less of the impact force and consequently have a higher chance of not getting injured.