Redesign of A Front Bonnet Targeted to Lightweight and Pedestrian Safety By Virtual Techniques

The use of innovative virtual test procedures is ever more important. They allow to reduce the development time and to pursue several targets at the same time. In design for active and passive safety¸ they are very useful in order to forecast the impact behaviour of car structures without making use of expensive prototypes and, at the same time, to reduce as much as possible the weight of the component/system with a consequent reduction in fuel consumption and carbon dioxide emission. Once excellent results in terms of active and passive safety have been obtained, the attention of car manufacturers and of the public opinion has been focused on the safety of the vulnerable road users (VRU), pedestrians and cyclists. Some examples concerning the redesign of a bonnet with the double target of weight reduction and pedestrian safety will be illustrated. Hybrid metal/plastic and more usual metal sheet solutions have been compared. The static performance (stiffness and denting resistance) as well as the impact against a pedestrian head have been evaluated by means of FEM models along with actual regulations. The design process of the bonnet in case of pedestrian head impact has been investigated also by using a head model in order to introduce and evaluate the possible advantages of the introduction of human models in the design process