14 DAY TRIAL // Car accidents have now turned into one of the main causes of mortality in the modern society and their number is increasing, in parallel with the number of cars on the roads. Annually, over 200,000 car accidents take place only in Germany.
That's why the car manufacturers dedicate a lot of time and effort (besides the financial part) on research in investigating the safety of the cars and in developing new methods to protect drivers and passengers.
The car body's design is important, but the quality of the employed steel is also crucial. During a crash, the steel elements must combine two different traits: they must be ductile to absorb most of the impact energy and meanwhile have enough shape stability to protect the passenger cabin.
A combined research of the Max Planck Society and the German Steel Institute (VDEh), led at the Max Planck Institute for Iron Research GmbH (MPIE) in D?sseldorf, Germany, has come with a new type of steel for such future requirements.
Basic experimental results for the TWIP steel show a high ultimate tensile strength (600-1100 MPa) and extremely large elongation of 60% to 90%, values satisfying the requirements of new generations of cars.
In case of an impact, the so called TWIP-steel (twinning induced plasticity) deforms but a forming capability (ductility reserve) is maintained. Each steel piece elongates, then strengthens and delivers the rest of the deformation energy to the surrounding pieces, which will also deform. This way, by spreading energy over the whole surface, the impact momentum is absorbed more effectively, offering the passengers a higher likelihood to survive the event.
In a few years, the new TWIP steel could be integrated into bumpers and side doors, the most vulnerable car parts in a crash. The TWIP-steel technology clearly shows that steel can still combine both tradition and novelty.