Abstract
Keywords
Crash box, Aluminium foam, Car over hang reduction, energy absorption, Danner application
Abstract
In Europe and Japan, compact cars are more and more present on the market. Architecture of such vehicle creates new problems with crash safety related to the reduced packaging length of the crash zones. The crash box concept is originally motivated by the large amount of car crashes taking place at 15 km/h speed where goals are to reduce intrusion and/or car over hang. Thus, cars makers manage to absorb energy during the impacts in a controlled manner (relative low crushing peak, progressive and repeatable deformation) in order to decrease insurance rates as a result of low repair cost. Foam filled profile and especially foam is used due to its isotropic intrinsic mechanical characteristics: high strength, high absorption capacity and progressive deformation. In the first part of the paper experimental and numerical studies on a crash box system, including foam blocks characterization and foam filled profiles, is detailed and compared to existing aluminium crash boxes. It is shown that aluminium foam filled crash box provide high performance ability for Danner crash, high efficiency answers in terms of crushing peak level and energy absorption. Above all, better styling possibilities are also provided. Indeed, according to Danner improvement it is demonstrating that foam filled profiles increase the performance reducing significantly the intrusion and/or reducing the packaging while absorbing the same level of energy. More precisely it is presented that, foam filled crash boxes, using aluminium envelope and aluminium foam made form metallurgical process, can overmatch conventional solution for Danner problematic, can offer new styling freedom with car over hang reduction and can allow pedestrian safety improvement with additional packaging space. Finally, extensive simulation work based on experience plan, aiming at the development of a designing tool helping in the different parameter choice according packaging space, is presented for 2 profile geometry.