Aluminum’s Contribution to Crash Management

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Aluminum’s many attributes include enhanced safety for vehicles on the road, thanks to its lighter weight and excellent crash management. These features are even more critical with the current market transition to battery electric vehicles.

ACTIVE AND PASSIVE VEHICLE SAFETY

There are two different forms of vehicles safety in the case of an unexpected road event. One, “active safety,” refers to the ways in which vehicles can avoid or mitigate an accident. In recent years, the development of sensors and artificial intelligence has significantly improved active safety. Aluminum contributes to active safety by reducing the weight of the vehicle, and consequently by improving the handling of the vehicle and reducing the braking distance: the best accidents are the accidents you avoid!

However, there are – and will always be – situations when a crash cannot be avoided. In such a case, passengers rely on “passive safety,” or the ability of the car body structure to manage the crash and limit the impact on the passengers.

Regional regulations, insurance companies, and road safety organizations such as the New Car Assessment Programme (NCAP) have defined rules to respect (e.g., seatbelts) and typical crash scenarios to assess the passive safety of vehicles. Aluminum offers vehicle body structure designers many options to manage these crash tests.

ALUMINUM BODY STRUCTURES PROTECT PASSENGERS  

Body structure safety engineers have two complementary strategies to assure passive safety. One is to create a strong reinforced cabin around the passengers, to minimize intrusions. The other is to multiply crumple zones around this cage which are deformed at a controlled level of force (resulting from an impact), ensuring controlled deceleration of the car during crash events.

A strong reinforced cabin (see image in red) demands high-strength materials. Aluminum is an ideal choice; high-strength/high-gauge alloys can be hot formed to leverage alloys with the highest tensile properties, and tubular parts with optimized gauge distribution can be built from extrusions.

Aluminum is also extremely efficient for crumple zones (see image in blue). Its energy absorption efficiency is over-proportional to material gauges—when you double the gauge, you triple the energy absorption capacity. Typically, automotive manufacturers can use aluminum sheet in a higher gauge than steel, for the same energy absorption and an average lightweighting of 45% (with typical steel & aluminium grades used in body-in-white).

Furthermore, aluminum crash alloys have been designed to offer excellent ductility in service that prevents unexpected behavior during large deformations, unlike some other materials with less ductility.

ALUMINUM PROTECTS BATTERIES TOO

We are witnessing a massive transformation in the global automotive market from internal combustion engine (ICE) vehicles to battery electric (BEVs), which are set to dominate production and sales by the end of the decade. Since current BEV battery technologies are based on flammable electrolytes, batteries must also be protected for the safety of passengers.

The same safety principles are applied to batteries as to people: they are placed in a strong cage (enclosure), with buffer areas to absorb energy. Once again, strong, lightweight, energy-absorbent aluminum provides the ideal solution. Battery enclosures are generally made from high strength & thick aluminum sheets, while aluminum extrusions are inserted into the rockers to act as buffers during the side crash.

ALUMINUM-INTENSIVE VEHICLES ENHANCE SAFETY OVERALL

In the event of a crash, aluminum efficiently protects a vehicle’s passengers through lightweighting and energy absorption. And since aluminum reduces mass, and therefore the kinetic energy transferred in an accident, an aluminum-intensive vehicle is safer for pedestrians, cyclists, and occupants of all types of other vehicles, too.