Aside from aerodynamics, resistance to rolling, and the engine efficiency itself, mass is the most influencing factor of fuel consumption and therefore vehicle emission.
Over the last years, the automobile industry has generally met the ever-increasing requirements on comfort and passive safety with increases in vehicle mass. However, with the European Community together with Automobile Manufacturers’ Association (ACEA), setting fleet average fuel consumption goals for 2008 to 5.81 petrol/100km (5.251 diesel/100km), this practice has to be not only stopped, but reversed. Very simply, it means that vehicle mass has to decrease while current and new legal requirements on passive safety will continue to have to be met. Additionally, comfort goals have to remain abreast of market demands.
The use of alternative, lightweight materials in the Body-in-White offers the possibility of reducing vehicle mass without influencing the general concept of the car.
The basis for an optimal vehicle structure is set in the initial phase of development. Consideration of implementing alternative materials has to occur at this stage in order to be successful. In order to be cost effective, these feasibility studies are primarily determined by simulation. For this purpose, it is imperative to have dependable models for these alternative materials, which can describe, not only their linear-elastic properties, but also the non-linear behavior and damage.
One common choice for lightweight material which is seeing more and more use in the automobile industry is aluminum which has only one third the density of steel.
This paper discusses the simulating and testing process for structural aluminum components in a BMW vehicle, starting with a general introduction to the problems of simulating aluminum alloys. BMW’s Z8 project is used as example, emphasis being placed on passive safety subjects.