Abstract
Keywords: passive safety, crash simulation, crash energy absorption, metal cutting
The increase of the passive safety as well as the need to reduce CO2-emissions and the protection of resources belong to the objectives concerning the automobile industry in present and future. To cope with the growing public interest on the passive safety, a permanent enhancement of passive protection systems is indicated. Essential development work in the areas of airbag systems, seatbelts, energy absorbing deformation structures, safe passenger compartments as survival space due to application of high-strength steels etc., shows the importance of the passive safety. Especially in recent years the passive safety has made a major contribution in reducing injuries and deaths. However, this fact resulted in the increase of vehicle weight. One solution to reduce weight is Multi-Material-Design, i.e. using different materials in consideration of their requirements (1). In many cases the use of different materials requires also new vehicle architecture concepts. Regarding their dimensioning and development, the energy absorption of structural parts plays among other things a major role. Vehicle structures such as a longitudinal rail or a crashbox for instance have to fulfil many functions and requirements. Especially the longitudinal rail has not only the function as a supporting element of engine, chassis frame and front-module, but also in case of a crash it has also to meet the demand to absorb as much energy as possible (2). Usually the automotive manufacturer chooses profiles for crash absorbing elements that have, as a result of their specific deformation behaviour (stable axial collapse behaviour), an oscillating force-deformation characteristic, which is not optimal concerning the energy absorption.
In this respect the DLR (German Aerospace Center) Institute of Vehicle Concepts presents a high efficient crash energy absorption method, which shows higher specific energy absorption and a smoother force-deformation characteristic compared to currently applied methods in the automotive industry. Testing results from the actual research work will be shown. Besides the experimental results FE-simulations will also be presented. Thereby the modelling technique, that enables a numerical simulation of this device for energy absorption will be discussed. Furthermore the question concerning the application of this method in simulations of full vehicle FE-models will be answered.