Study On Composite Engine Hood Design Based On Pedestrian Protection

With the development of automotive and improvement of people’s safety awareness, pedestrian protection is gaining more and more attention. The collision between pedestrian head and engine hood or windshield was the most important reason for fatal pedestrian head injuries when vehicle impact to pedestrian. In order to improve safety of engine hood, a variable thickness composite hood was designed in this paper, and the simulation models were created by HYPERWORKS then collision simulation analysis were carried out by using LS-DYNA software.A vehicle’s engine hood finite element model was used in this paper, and headform impactor collision into the engine hood model was created according to Euro NCAP regulation requirement, finally, the pedestrian safety performances of original steel engine hood were obtained, the results showed that the pedestrian head safety of the original engine hood was poor.The structure form of the composite engine hood studied in this paper has no inner ribs structure, and it consists of upper and lower carbon fiber composite laminated plates and intermediate foam material. The thickness of foam in new designed composite hood was different between adult head impact zoon and child impact zone, furthermore, the foam above the engine was thickened in order to avoid colliding with the hard engine after the first collision which called a secondary collisionA finite element model of pedestrian head impact with the composite engine hood was created and then the related performances of the hood were analyzed. The pedestrian safety analysis results showed that: at the same points of two engine hood the HIC values of composite engine hood were less than ones on the original hood and meet the regulation requirements for pedestrian head safety; the new designed composite hood has a better effect of pedestrian head protection compared with the original one. Lightweight effect analysis was carried out, the weight of the composite engine hood only has 15.6% of the original engine hood. Torsional and latch beam stiffness tests model were created, and the result showed that the mechanical properties of composite engine hood were better than the original.This paper offers a reference for the application of composite to the engine hood.