Crumple Zones Save Lives

The aftermath of car crashes is not a pretty sight. All too frequently the car or cars involved are a tangled mess of metal on the back of a truck even after relatively low speed collisions.

The bad news is that the car may be a write-off, but the good news is that these days the driver and passengers are highly likely to have survived the crash relatively unharmed.

It wasn’t always this way. In the bad old days when cars were rigid and strong drivers and passengers would frequently die in crashes that all too often left the car with little damage. The life-saving technology that completely revolutionised car safety is the crumple zone and for that we have Mercedes Benz and their brilliant engineer Bela Barenyi to thank.

Genius of Bela Barenyi

Barenyi was an engineering genius responsible for more than 2500 patents, a figure which left even Thomas Edison in the shade. Most of them had something to do with car safety.

Barenyi rejected the idea that a safe car was a strong, rigid one. He clearly recognised that the kinetic energy – the energy of motion – involved in a collision needed to be dissipated by deforming the bodywork in front of and behind a strong passenger compartment to protect the occupants. The aim was to slow down collisions and absorb their energy to reduce the difference in speeds between the vehicle and the driver and passengers.

In 1951 Barenyi patented his design ideas with patent DBP 854.157, but it’s far better knows as the “crumple zone”. Barenyi is rightfully known as the father of passive safety.

Mercedes first incorporated its patented crumple zone into its 1959 W111 series. Possession of that patent could have given Mercedes a huge commercial advantage, but to the German carmaker’s great credit it decided not to enforce its patent rights, but to allow others to adopt the technology as well. It’s a decision that’s saved countless thousands of lives worldwide.

In the years since its invention crumple zones have become a feature on all cars, with passengers encased in strengthened steel cages protected by crumple zones of metal and plastic that fold in on themselves in a crash.

Crumple zones combined with seat belts, air bags and padded interiors now play a vital role in absorbing the impact of the human body in a collision and reducing harm, particularly to the vital internal organs and the skull.

Side impact safety

In the 1990s Volvo launched it Side Impact Protection System (SIPS), a crumple zone designed to protect the occupants in a side-on collision that’s now standard on all Volvos. It combines strengthened B-pillars with a reinforced doorsill, roof rail and floor members to dissipate crash forces around the safety cage while reducing passenger compartment intrusion.

Improvements in steel and other materials like magnesium, carbon fibre and aluminium have also improved cars’ ability to dissipate impacts and absorb energy while protecting the occupants in greatly strengthened passenger compartments. Manufacturers such as Volvo now use varying grades of steel and aluminium in their cars.

"Improved steel qualities have made it possible to achieve better safety structures without sacrificing weight," Levenstam says. "You can achieve better crumple zones with mild steel and superstrong safety cages with high-strength steels," said Volvo engineer Marten Levenstam of Volvo Cars Safety Centre.

Lightweight plastic components are also being incorporated into crumple zones to absorb energy and save weight.

It’s not just car bodies that are being designed to crumple. Composite driveshafts are being made of carbon and polymer fibre so that they disintegrate into smaller fibre fragments in a crash to reduce danger.

Computer modelled crash simulations using technology developed for the nuclear and aerospace industries have helped carmakers to design cars with better structures and materials, greatly speeding up the development of safer cars.

Small car safety

The challenge Volvo faced developing its SIPS, where there is little space between the car’s occupants and a colliding vehicle or other object is also faced by small car manufacturers. It’s an interesting reflection on the advances in crumple zone technology that many small cars now boast ANCAP 5-star safety ratings.

As ANCAP says on its website “Some small cars do remarkably well in crashes with larger vehicles as they have very strong passenger compartments and advanced occupant restraint systems and these features can help mitigate the risk of the mass disadvantage.”

Crumple zones have played a major role in making Australia’s roads a great deal safer. Since 1975 we’ve seen annual road fatalities plunge from 26.59 per 100,000 people to just 4.92 in 2014.

Thanks to Bela Barenyi’s brilliant invention, you’re far more likely to survive a car crash today that would have killed you 40 years ago.

Blog image: Volvo V70 - Safety Cage, Author: https://www.media.volvocars.com/global/en-gb/media/photos/list, Date: 27 February 2007

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Categories: Technology, Safety
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