Design Of New Composite Material Engine Hood Based On Pedestrain Head Protection

With the development of automotive safety, pedestrian protection is gaining more and more people's attention, many countries have formulated a series of pedestrian injury evaluation, Europe and Japan are included. During the impact between the vehicle and pedestrian, the head of the pedestrian can easily hit on the engine hood or even windshield to cause fatal injury. In order to reduce the injury during the impact, in this thesis a kind of composite material engine hood was designed, the simulation models were created by using LS-DYNA, the material mechanical and structural parameters which have the best function of head protection were obtained.A vehicle finite element model was used in this thesis, the finite element models of pedestrian headform impactor impacting the engine hood accordance to the statute of EEVC WG17 were created, did the simulation by using LS-DYNA, the injury values of the original steel material engine hood were obtained. The results show that the testing points above the engine hood hinge and suspension tower can result in higher values of head injuries.Foam composite panel consists of upper and lower carbon fiber composite laminated plates and intermediate foam material. How to manufacture the form composite material and how to use the mechanical properties of carbon fiber layer to calculate the mechanical properties of the carbon fiber composite laminated plate were introduced in this thesis.Static compression and impacting simulations of the carbon fiber composite laminated plate and foam composite material were carried out, Mechanical experiments were used to verify the correctness of the simulation models. Simplified models were used to analysis the influence of material parameters of the foam composite material on the injury value of the pedestrian head during the impact. The finite element models of pedestrian headform impactor impacting the foam composite material engine hood were established. The material parameters which have the best function of head protection were studied by using orthogonal test method. In the end, the result that the structure of ladder-type foam composite material engine hood have the best function to protect pedestrian head was obtained, with this type of engine hood the average injury values of adult are reduce by 35.0%, the average injury values of child are reduce by 8.0%. The simulations of vehicle frontal impacting were carried out, the result shows that the new material has the same performance of the frontal impacting. Lightweight analysis was carried out, after using the new material the engine hood is only 54.15% of the original weight.This thesis offers a basis for the new composite material to applying on the vehicle body, and offers a reference to designing of composite material engine hood with pedestrian head protection function.