A Study On Structure Safety Of Passenger Car And Occupant Injury Prevention In Rear-End Impact

Passenger car rear-end crash is one of the major categories of the urban road traffic accidents, the incidence is ranking after the front and side impact categories. This type of accidents ranked first of all accidents on national freeways. The neck injury is one of the typical injuries occurred frequently in rear-end impact. Moreover, the fires resulting from fuel spillage are likely to happen in this type of accidents, which can lead to additional property losses and casualties. So how to prevent fuel spillage risk and injuries from rear impacts becomes an increasing problem in the filed of vehicle safety.In order to study on vehicle crashworthiness and the integrity of fuel systems of vehicle in rear-end impact, a finite element model of car was adapted. Then, according to the new FMVSS 301 requirement, an FE model of passenger car was built and validated with available experiment data to make an analysis of the rear impact. Furthermore, the rear bumper and rail structure were optimized by using orthogonal experimental design (OED) and comprehensive equilibrium methods. The effects of 4 parameters of thickness and type of material of rear rail and rear bumper on integrity of fuel system of the car were considered as main design parameters. The main objective of optimization was the maximum effective strain of fuel tank. The secondary objectives were the energy-absorbing capability of rear rail and rear bumper and the deformation of tank structure around.In order to study on the risk of passenger injuries in rear-end impacts, a multi-body model of rear-end impact were developed and validated. The model was used to investigate the influence of driver seat on driver injuries in terms of design parameters, such as distance between head and head-restrain, obliquity of seat back, seat cushion, and stiffness of seat back.According to simulation results, the following conclusions were made.The simulation results of rear impact analysis model showed that the maximum effective strain of fuel tank was reduced by 50.7% after optimization of the design parameters of rear bumper and rear rail. The approach of mathematical models combined with optimization procedures is very useful in the design of car body structure, considering the improvement of passenger car crashworthiness.Simulation results of multi-body model showed that when the vertical distance between head and headrest within a certain range, there was no marked change on driver injury parameters, once the distance beyond the boundary, the risk of head and neck injuries of driver increased distinctly. Either raising or lower of obliquity of cushion will increase the risk of neck injuries.