Influence Of Seat Parameters On Neck Injury Risk Based On C-NCAP Whiplash Test

Whiplash injury indicates the neck injury of passengers during low-speed rear collisionsof automotive. Viewed as one of the most frequent injuries of all accidents, it haveengendered great social economic loss and destroy humorous human lives. Therefore, inorder to measure the frequency and severity of the passenger’s neck injury during alow-speed rear collision, and to evaluate the protections from whiplash injury of front seatsand headrests, the China’s New Car Assessment Procedure(C-NCAP) officially includes the“neck protection test of rear impact (whiplash test)” to its test programs in the year2012. Inabsence of the revelation to accurate neck injury mechanism, this new rule is to providecriteria to evaluate the performances of the seat during the whiplash test, pointing a moreclear direction to manufacturing improved seats.The method of muti-body is applied in this paper, based on the actual performance ofthe front seat of a certain B-class car in the whiplash test, an analysis model combined with amuti-bodied seat and muti-body BioRID II dummy is established for simulation. Themodel’s validation is later evaluated. Take this model as a fundamental one, through alteringthe determining parameters of the seat and headrest and comparing the stimulation results,the influences of headrest position, headrest stiffness, the connection stiffness betweenheadrest and seatback, seatback stiffness and the adjust stiffness to dummy injury areanalyzed. The outputs of this model consist of seven injury indicators to the C-NCAPwhiplash test requirements, including upper and neck shear forces Fx+, upper and lowerneck tensions Fz+, upper and lower neck torques My and the NIC indicator.The results of seat design parameters influencing neck injury in the whiplash testindicate that, within rational range, the closer between headrest and passenger’s head, thesafer it seems to be for the neck protection, however, a majority of neck injury indicators ismore sensitive to the height of headrest. The subordinated torque of the adjust have a greaterinfluence on the upper-neck force, upper-neck torque, and the NIC indicator, simultaneouslythe other neck injury indicators were subjected to both subordinated torque and elasticspinning stiffness. As a result, the softer the adjust tends to become, the more beneficial. This paper also established preliminary research about how the impact impulse and its velocityimpact the neck injury, the results demonstrate that with same level of impact velocity, atriangle impulse is easier to generate neck injury than a square impulse, when with sameimpulse, the higher the velocity is, the severer the dummy suffer.