The Physics of Car Crumple Zones: How Do They Work?

Reviewed by

Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on November 6th, 2023

Reading Time: 4 minutes
Summary
  • Crumple zones are the areas designed to break down upon impact. They’re usually at the front and rear of the vehicle.
  • These zones create a buffer zone so that it’ll take longer for vehicles to completely stop. This creates a decrease in kinetic force before the impact reaches the occupants.
  • Crush zone designs typically include frame segments designed to bend or collapse during a crash. Some vehicles also feature a steering column engineered to collapse to minimize impact.

Vehicle parts should ideally be sturdy enough to bear the impact of a collision and keep occupants safe. Interestingly, there’s a good reason for some parts to be the opposite. The presence of less rigid crumple areas in your car can actually reduce impact during an accident.

What Is a Crumple Zone?

Crumple zones in cars refer to areas that are specially engineered to break down upon impact. These crush zones are usually at the front and rear of the vehicle.

How Do Crumple Zones Work?

Crumple zones in cars refer to areas that are specially engineered to break down upon impact.

Keeping people safe during car crashes is tricky, even with safety measures like seatbelts and airbags in place. To make the impact of collisions less devastating to passengers, engineers tapped into physics and designed crumple zones. Here’s an example of how they work:

Let’s say a vehicle is traveling at a speed of 60 mph when it suddenly crashes into a post.

Based on the law of inertia, the occupants will continue to travel at this speed until they hit something that stops them (window or dashboard). Traveling at that speed means that there’s a high chance that they’ll be severely injured, especially if they hit hard surfaces.

Engineers aimed to take away the force from the occupants when they created crumple zones. To accomplish that, they have to redistribute the force before it can reach the driver and the passengers.

Their solution? Create a buffer zone so that it’ll take longer for the vehicle to completely stop. In this way, there will already be a decrease in kinetic force before the impact reaches the occupants.

What’s In a Crumple Zone?

The materials used for crush zones or crumple zones vary depending on your ride’s automaker. There’s not much information online about them because these details are usually considered proprietary information.

Simple crumple zone designs include frame segments engineered to bend or collapse during a crash. On some vehicles, the steering column is also designed to collapse to reduce impact. Some automakers use metals to absorb kinetic energy. Plastic and plastic composite materials are also perfect for crumple zones because they’re lightweight.

Crumple Zone Testing

Institutions like the National Highway Traffic Administration (NHTSA) and the Insurance for Highway Safety Institute (IIHS) perform vehicle crash tests.

The NHTSA rates how a vehicle performs in a front-end collision, assigning a rating from one to five stars based on the outcome of the crash test. Most crumple zones are at the front end of the vehicle, so you can use this rating to assess how effective a particular vehicle’s crumple zones are.

When Were Crumple Zones Invented?

Crumple zones were introduced in the 1950s. Béla Barényi, an engineer who worked for Daimler-Benz, integrated them on the Mercedes-Benz W111 Fintail in 1959.

Other Car Safety Features That Can Save Lives

Aside from crumple zones,  here are other safety features you can find on cars:

Airbags

Airbags automatically inflate during severe front-end and side collisions, cushioning occupants from the harsh impact. Some modern vehicles feature thorax airbags with head protection.

Seatbelts

If you’re not buckled up during a major crash, the impact might eject you from the vehicle, so always use your seatbelts. Secure them properly to avoid fractures, contusions, and other injuries.

Head Rests

Also known as head restraints, these parts come as a standard feature in all vehicles because they can reduce the risk of whiplash and similar injuries during a collision. They’re ideally at eye height or close to the back of the head for maximum protection.

Reverse Camera

A reverse camera is helpful when you’re parking or when you’re trying to safely exit your driveway without hitting something. If your vehicle doesn’t have one, there are a lot of aftermarket options available online.

Shatter-Resistant Glass

Glass usually takes damage during crashes, and it’s dangerous when it shatters to pieces. The sharp shards can add to people’s injuries. That’s why many modern windshields have shatter-resistant laminated glass, which can withstand impact without breaking to pieces.

Make-Specific Safety Features

Some automakers continue to find ways to ensure people’s safety during collisions. Consider Volvo’s Safety Ride Down concept.

Crumple zones are tricky to apply to compact cars because of their limited space. That’s why Volvo developed an additional impact-absorbing technology for small units like the Volvo 33C.

In this type of system, the seats are mounted on a sled-like structure equipped with shock absorbers. During a collision, the seats move forward at the same time the frontal crumple zone is deformed.

The shocks absorb the impact, slowing down the seats’ movement. The steering wheel and a part of the dashboard will also move forward to accommodate the driver.

Stay Safe While On the Road

Driving always comes with risks, and it can be comforting to know that many safety features can help lessen your injuries during a collision. However, you shouldn’t rely on crumple zones or other safety features to keep your passengers safe.

The best thing to do is to practice safe driving and pay attention to your surroundings to avoid getting involved in a collision. Avoid driving when you’re under the influence of alcohol. Make sure to focus on the road, and avoid any distractions.

About The Authors
Reviewed By Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Tony Harlin is a Master Gas and Diesel Diagnostic Technician with over 18 years of experience. He works full-time at a large independent automotive shop as a driveability and repair technician working on all types of vehicles with a focus on diesels. ASE certifications include A1-A9, L1 and L2, as well as X1.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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CarParts.com Research Team and Anthony Harlin, ASE Certified Master Automobile Technician
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