| Now it is a hot research project on vehicle crash safety in China. The major objective is how to decrease the injuries and deaths of passengers and pedestrians in collisions. A MADYMO simulation model was established to analyze the passenger restraint systems. A new theory about passenger restraint systems has been put forward and further research is in progress.The sum total of study on the subject is contained as follows:1,The present development situation of belts, airbags and safety seat at home and abroad, and the statistic data of accidents were analyzed. The conclusion that the passenger restraint system can protect the passengers and there is potential danger was drawn. So we need to develop the intelligent passenger restraint system accordingly.2,The development trend of the current intelligent passenger restraint system was researched. There are the following problems: 1) unreasonable belt restraint system; 2) the injuries to the body from the deployment of airbags; 3) short of effective protection to the passengers in frontal impact from safety seat.3,The seat cushion with the adjustable mechanism which increases the angle between the seat cushion and floor in collisions is developed. As a result, the pelvis and leg was restrained to sustain higher load and increase restraint system efficiency.4,The recent energy absorbing system used in sled test system was analyzed. Based on the analysis, the pulse regained theory of steel rods damping absorber in sled tests was researched, developed the steel rods damping absorber. According to single steel rod damping force-sled displacement curve, the program about putting steel rods was set up in the experiment. The result showed that this program is able to represent the pulse of collision in a good way.5,The vehicle cabin model was built up in MADYMO. The cabin is made up of floor, firewall, dashboard, accelerator pedal, toe board, windshield, roof, A-pillar, trim, seat, steering system containing cross member, steering column bracket, inclination adjustor, energy absorbed steering column, steering wheel etc. The restraint system is made up of the folded airbag system, belt retractor, pretensioner, load limiter, height adjustor, fixed anchor point, buckle etc. The 50tile Hybrid-III male dummy is sitting in seat according to test dummy posture. The properties of components, load and contact were defined. The simulation results were validated according to the test results.6,The influence of different cushion angle on dummy injuries by the simulation model was analyzed. The results indicated that the head injury index decreased by 21.4%, the chest injury index decreased 16.6%, the pelvis injury index increased only 8.2% and the leg injury index kept low during increasing from 10 to 25 degree in collision. It indicated that the inclination adjustor of seat cushion can supply much better protection to occupants.7,The stiffness of seat belt, the pay-in of pretensioner, the level of load limiter, the mass flow rate of airbag gas generator, the area of airbag vent hole, the permeability coefficient of airbag fabric coating, the stiffness of cushion were selected as the design variables. Then the parameters sensitivity analysis was finished by ModeFRONTIER. The main factors which influence injury criterion of occupants were confirmed.8,The former six parameters were chosen as the design variable of the optimization, the probability of combination injury was chosen as the aim of optimization. Response surface method of head injury criterion, thorax cumulative 3ms injury criterion to the design variables was used to optimize. The head and chest injury criterion is remarkably reduced after the optimization. The other injury criterions don't have obvious change. The head injury criterion is reduced by 43.4%, the probability above AIS4 level of the head and chest combination injury is reduced from 4.0% to 3.2%, it improved the effect of occupant protecting significantly.Finally, we discuss the problems about the cushion inclination adjustor.
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