Low-speed rear-end collision car accident neck injury of crew

Vehicle traffic accidents have become a threat to the world．Traffic accidents not only caused a large number of fatalities，but also enormous social economy loss every year all over the world． It is reported that neck injuries is the most common injured human body part among all the type of accidents，which is especially remarkable in the rear-end collision．The neck injury as high as 77．1％in the rear-end collision，and in most cases，these injuries are occurred at low speed(A V≤ 25kmha)situations．For this reason,it makes great SISe to guide the design of vehicle structural safety and prevent neck injuries in rear—end impact and further reducing or eliminating neck injury and other types ofinjury by study of the neck injury． The dynamic of head and neck during rear-end impact is studied in the present paper by means of computer simulation：A rear-end impact model with BioRID II dummy was built based on simulation program MADYMO，which including driver,vehicle environment model，restraint system(seat model and hybrid safety belt model)，to study the influence of seat properties，such as backrest inclination angle，head restraints position and tilt angle，backrest contact rigidity distribution，recliner rotation stiffness and yield strength characteristic Oil neck injuries．The results of this analysis showed that the backset angle，head restraints position，seat back stiffness and recliner stiffness have great influence on occupant head-neck dynamic response，and neck injury risk Can be reduced by proper seat design．The output parameters include head and the first thoracic verteb acceleration，predicted segmental rotational angles，neck shear force，axial force and extension moment，Neck Injury Criterion NIC，and shear moment neck injury criterion Nkm． The NIC and Nkm were used to assessment of neck injury risks and evaluate the performance of vehicle seat for neck injury prevention based on simulation result． The analysis results above showed that the backset angle，head restraints position，seat back stiffness and recliner stiffness have great influence on the occupant head—neck dynamic response． This suggested that the neck injury risk could be reduced by diminishing the seat back angles，by positioning the head restraint higher and closer to the head with an appropriate larger tilt angle，by softening the upper seat back while stiffening the lower seat back，and by equipping the deformable recliner with a larger rotation stiffness and lower yield strength characteristic． Finally,the occupant restraint system improving manner,as well as new types of Rear Pre．．Crash Safety System design was proposed base on these analyses above．

Key words：Rear-end Impact；Neck Injury；Biomechanics；Seat；Restraint system；Rear Pre-Crash Safety System