Pedestrian safety investigation of the new inner structure of the hood to mitigate the impact injury of the head

• All of the new developed hood inner structures were involved in the energy absorption phenomenon, so the HIC values are reduced significantly.
• Not only did the hoods get stiffer but the HIC values also decreased significantly.
• The composition of wavy–conical design leads to a much better result in HIC and it also has higher torsional/bending stiffness than the original one.

Increasing the safety of the road transportation leads to reducing the costs of road accidents, especially improving the safety of the pedestrians who are the most vulnerable road users. Regarding the new regulations on the pedestrian safety, automakers have recently paid certain attention to the front-end design of the vehicles. The collision of the pedestrian's head to the automotive hood is the main reason for fatal injuries in pedestrian to vehicle impacts. Head Impact Criteria (HIC) measures the possibility of inducing serious injury to the pedestrian's head in collision with the hood.In this paper, a new finite element model has been developed to simulate the collision between headform impactors and five different hoods according to the EEVC WG17 regulation requirements. This model was utilized to compare pedestrian friendliness of four hoods with four new different inner layers including hemispherical, conical, wavy, and the combination of wavy–conical structures to the original hood and the engine parts are modeled as rigid.It is shown that the pedestrian safety has rigorously improved in the new structures with respect to the original one. In the new designs, the entire structure is involved in energy absorption so it leads to the mitigation of head acceleration to a certain level.Finally, the masses of different structures are compared and it is illustrated that the new structures are not much heavier than the original structure. Moreover, the torsional and latch stiffness of the new structures are much better than the original one.