The Research On The Passive Safety Of Driver-side Seat In The Multiple Conditions

When occurs collision, vehicle seat is one of the most important parts which protect occupant, so the research on the passive safety of driver-side seat in the multiple conditions is of important theoretical significance and engineering application value. Based on the occupant area of one car, this paper studys the protection of driver-side seat for driver neck and rear occupant in the frontal and rear collision. The following several aspects of research are carried out:(1) Based on the related size and performance parameters of one car occupant area, through crash simulation software MADYMO, this paper built up the complete frontal collision restraint system simulation model with front and rear occupant, rear collision driver restraint system simulation model, which were verified by tests.(2) The motion state of the driver in the frontal collision was divided into three stages. Using the established frontal collision simulation model, in the three stages of frontal collision, the influence of the vent leakage coefficient of airbag, the mass-flow rate of gas generator, the fabric permeability of airbag, the fabric elongation of safety belt, the locking hysteresis effect of retractor, the preload quantity of pretensioner on the injury of every part of driver and the occurrence time of peak injury value were studied. Taking whole injury criterion WIC as the optimization goal, the whole driver restraint system was optimized, in order that driver obtains the best protection in the first stage of driver’motion(the early period of frontal collision). After driver obtains the best protection in the first stage, in the second and third stage(the late period of frontal collision), the motion state of driver’upper and lower neck and the influence of the front headrest stiffness, upper backrest stiffness, lower backrest stiffness and recliner rotational stiffness of driver-side seat on driver neck injury were analysed.(3) Using the established rear collision simulation model, in the rear collision, the motion state of driver’upper and lower neck and the influence of the front headrest stiffness, upper backrest stiffness, lower backrest stiffness and recliner rotational stiffness of driver-side seat on driver neck injury were analysed.(4) This paper putted forward a neck whole injury criterion NWIC for considering neck protection in both the late period of frontal collision and the rear collision. Taking NWIC as the optimization goal, the front headrest stiffness, upper backrest stiffness, lower backrest stiffness and recliner rotational stiffness of driver-side seat were optimized by the response surface analysis method, obtaining the optimum combination of the four characteristic parameters. The simulation results indicate after optimization, driver neck iujury declines obviously in the two collisions:in the late period of frontal collision, the peak moment of extention of upper neck Mupper, the peak moment of extention of lower neck Mlower, Nkm and Nij decreases52.31%,33.59%,48.86%and28.95%respectively, the peak shear force and axial force of upper neck, the peak shear force and axial force of lower neck decreases32.51%,28.55%,42.96and23.89%respectively; in the rear collision, the peak moment of extention of upper neck RMvper, the peak moment of extention of lower neck RMlower and the peak value of neck injury criterion NICmax decreases36.84%,47.55%and40.95%respectively, the peak shear force and axial force of upper neck, the peak shear force and axial force of lower neck decreases43.71%,35.91%,42.84%and46.31%respectively, NWIC decreases41.24%.(5) This paper putted forward the new idea of automobile driver-side safety seat, in order to reduce the injury of the head, neck, other parts of rear occupant when rear occupant head hits driver-side seat headrest in the action of the inertial force of frontal collision. The simulation results show that:with the decrease of the turuing spring rotational stiffness in the safety seat, the head injury, chest injury and neck injury of rear occupant show a trend of decline. Considering passive safety and comform of seat, this paper determined the optimum rotational stiffness of the turning spring as10N·m/°. Compared to the original seat, head injury criterion HIC15, thorax3ms resultant acceleration T3MS and the peak moment of extention of occipital Myoc decreases24.4%,6.81%and22.38%respectively, the above shows that the protection effect of the new safety seat is obvious.(6) This paper conducted a matching optimization study bewteen the new safety seat and the design parameters of rear female occupant restraint system:﹕elected the rear headrest stiffness, rear backrest stiffness, recliner rotational stiffness of driver-side seat, the elongation and the D-ring height of rear-row safety belt, and rear seat cushion stiffness to conduct sensitivity analysis, to determine main factors affecting rear female occupant injury;②according to the results of sensitivity analysis, chosen the former five design parameters as the optimization design parameters, taking a new definition of whole injury criterion of rear female occupant WICF as the optimization goal, the response surface analysis method of HIC15, Myoc, Thpc to various optimization design parameters was used, in order to determine the optimum design parameters;〢fter optimization, rear female occupant injury declines greatly, HIC15, Myoc, the left and right thigh axial peak force Fleft, Fright decreases37.76%,56.08%,37.76%and56.08%respectively, WICF falls32.89%, the above shows the optimizatoin effect good.Summarily, in the late period of frontal collision and the rear collision, as the front headrest stiffness, upper backrest stiffness and lower backrest stiffness of driver-side seat is45N/mm,30N/mm and50N/mm respectively, the recliner rotational stiffness falls by60%compared to the original value, driver neck injury falls significantly at the same time; in the frontal collision, as the turning spring rotational stiffness is10N·m/。, the rear headrest stiffness and rear backrest stiffness is30N/mm,36N/mm, the recliner rotational stiffness falls by60%compared to the original value, the elongation and the D-ring height of rear-row safety belt is13%,0.85m respectively, the injury values of rear female occupant decrease significantly.