Design And Safety Analysis Of Active Hood Hinge Device

In recent years, with the continuous growth of the global automobile ownership,the incidences of road traffic accidents are also rising. Pedestrians as vulnerable groups in road traffic accidents,and damage suffered by their heads is the main cause of their death. In the course of frontal collision between pedestrians and automobile,the collision area of the pedestrian head is generally concentrated on the hood. As the traditional hood is close to the high point below it, it is easy to cause secondary damage to pedestrian head. Based on the above reasons, the hinge of the traditional hood has been improved in this paper, and an active hood hinge device is designed and analyzed.Firstly, this paper analyzes the technical defects of the existing hood hinge in the collision between pedestrians and automobile by TRIZ theory, and then innovatively designs an active hood hinge device. UG software is used to establish the three-dimensional model of the active hinge device, and then a series of kinematics and dynamics simulation analysis is carried out by using UG motion simulation module. The results show that the device meets the corresponding requirements, and the feasibility of the design is verified.Secondly, according to the requirements of national standard "car on the pedestrian collision protection" (GB/T 24550-2009), UG software is used to establish the three-dimensional model of adult and child headform impactor respectively, then,the 3D model is imported into the finite element software HyperMesh to establish the finite element model. The dynamic performance of the model is analyzed, and the results show that the model meets the requirements of application.Then, a three-dimensional model is established with reference to the actual size of an automobile hood. In accordance with the relevant provisions of the national standard, the finite element model of the collision including the headform impactor,active hinge device and hood is established. Collision area on the hood is divided by the national standard, then the arrangement of the key parts in the engine compartment of the experimental automobile is simulated and the five collision points on the hood are selected, which provides the basis for the safety analysis of the active hood hinge device.Finally, the finite element software HyperMesh and the solver LS-DYNA are used to simulate the head synthesis acceleration and HIC values of the five collision points selected in the two cases before and after lifting of the hood. The results show that the head synthetic acceleration decreases by 20.9 % after the hood is lifted; HIC value decreases by 60.5 % after the hood is lifted, and the HIC value is less than 1000 after the hood is lifted,thus making the pedestrian head in a safe range. It can be concluded that the active hood hinge device designed in this paper plays an important role in the life safety of the pedestrians.