Simulation Analysis And Research Of A Car Seat Based On Whiplash Test

With the rapid development of national economy, more and more vehicles are neededto meet citizen’s demand; as a result, automobile population is steadily increasing. Thenewly registered cars reached21.88million in2014,17.07million increment ofpreservation, both of which are the highest level in history. However, rising rate of trafficaccidents comes with convenience, especially the rate of low-speed collision. Sincewhiplash test is included in C-NCAP which is implemented in2012for the first time, majorcar companies pay increasing attention on whiplash test. The paper analyses the simulationresult of whiplash test conducted on a seat, which obtains score according to C-NCAP, andthen explores the impact of different seat parameters on the results of whiplash test in orderto provide reference on structural improvements of seat. The full paper is divided into fivechapters:The first chapter introduces background, purpose and significance. Analysis ofmethods and research status related to neck injury, describes regulations, standards aroundthe world of seat system and the relevant whiplash test regulations are compared betweenEuropean Euro-NCAP, the US IIHS, Japanese J-NCAP and Chinese C-NCAP.The second chapter introduces the establishment of a multi-body seat model usingsoftware MADYMO, based on geometry and performance parameters of a seat that isprovided by enterprise. Secondly, adjusting and positioning BioRID II dummy, building athree-point seat belt model and defining the contact between the dummy and the seat, theseat belt and dummies. Finally, the whiplash test model is finished by loading the model inC-NCAP way.The third chapter introduces whiplash test rating rules and dummy neck injurycomputing. Simulation results of whiplash test model are analyzed and scored by sevenindexes including NIC, upper neck shear force, upper neck axial force, upper neck torque,lower neck shear force, lower neck axial force, upper neck torque. Judging from whiplash test scores, seat the seat is a reasonable design; However, judging from the actual value ofeach index, there is a reduced space. So the next step to explore the impact of the seatstructure parameters on each evaluation, in order to further reduce neck injury.The fourth chapter discusses the seat parameters’ effect on the neck injury from threeaspects. First, headrest stiffness: change headrest contact stiffness and head rotationstiffness respectively, use0.5,1,2as the level of the three factors, then respectivelymultiplied by the initial stiffness and rotational stiffness curve to change headrest contact,the simulation result is carried out in accordance with the whiplash test seven scoringindexes. The results, by comparing, show that the greater in head stiffness, especially thegreater in headrest contact stiffness, the smaller injury in neck, and the better in test result.Second, backrest stiffness: change the upper, middle and lower stiffness of the backrestrespectively, use0.5,1,2as level of the three factors, then multiplied by the initial stiffnesscurve of backrest of a chair to change the backrest stiffness of the three parts respectively,the simulation results is carried out in accordance with the whiplash test by seven scoringindexes.The results, by comparing, show that reducing the central and upper stiffness andincreasing the lower stiffness will make the test results better. Third, head position: changeheadrest horizontal position and vertical position respectively, use-20mm,0,20mm asthree factors to change the location of the headrest in horizontal direction and verticaldirection. The simulation result is carried out in accordance with the whiplash test by sevenscoring indexes. The results, by comparing, shows that the closer to the head in horizontaland vertical direction of headrest, the smaller injury in neck and the higher scores in test.The fifth chapter is summary of full text, mainly contains the content and conclusionsand prospect of the research.