Research On Performance And Optimization Of Multi-chamber Airbag In Side Impact

According to statistics,in various traffic accidents caused by vehicles,side impact is the second only to frontal impact with a probability of occurrance of 30%.Due to the structure of vehicles,there is no large energy-absorbing space on the side compared with the front or the rear of a car.Thus,the relatively weak side structure and the smaller occupant-structure distance result in more serious occupant injury in side impact.Side impact safety is explicitly required and incorporated into regulations by countries all around the world,and it has become a hot topic in vehicle impact safety research.The main measures can be taken to reduce occupant injury in side impact are improving vehicle side crashworthiness and equipping side occupant restraint system,and side airbag protection system,including curtain airbag?CAB?and side airbag?SAB?,is an important part of it.In this paper,based on side impact test of a certain vehicle,a PSM sub-structure model was established using MADYMO to finish the research on its side airbag protection system.The result indicated that side airbag system of the vehicle did not meet the C-NCAP high performance requirements for the occupant's thorax and abdomen protection.In order to improve the protection effect of occupant,a multi-chamber thorax-pelvis side airbag was proposed.The airbag was divided into upper and lower chambers in vertical direction to respectively protect thorax,abdomen and pelvis area.Moreover,the upper chamber was divided into two independent chambers in the impact direction.The two upper chambers were independent and inflated by one inflator with multi airway tubes.The gas flow rate and diameter of vent hole were adjusted to control the different stiffnesses of different chambers,as a result,secondary buffer could be created to reduce the acceleration and compression of the occupant's thorax.Based on finite element simulation technology,the proposed multi-chamber airbag was simulated and verified by MADYMO.The result showed that new airbag eliminates the‘breakdown'phenomenon,and effectively reduces the injury value of the occupant.Then the optimization method based on agent model was used to optimize the parameters of the new airbag.The gas flow rate and vent diameter of each chamber were selected as optimized parameters,and a quadratic polynomial response surface model based on Latin Hypercube method was established and verified.Finally,a high-dimensional multi-objective optimization model was carried out with the target of the injury index?including chest compression RDC,chest viscosity index VC,abdominal force APF,and pubic force PSPF?in the C-NCAP,and parameters of multi-chamber airbag were optimized.The optimized airbag model reduced the injury of dummy's thorax,abdomen and pelvis while ensuring no great changes in head injury.Compared with initial design,the optimized multi-chamber SAB increased the HIC₃₆ by4.14%,decreased the RDC by 13.14%,decreased the VC by 20.16%,decreased the APF by15.62%,and decreased the PSPF by 10.13%.Compared with single chamber thorax SAB,the optimized multi-chamber SAB decreased the HIC₃₆ by 13.08%,decreased the RDC by 28.97%,decreased the VC by 23.7%,decreased the APF by 43.29%,and decreased the PSPF by 20.37%.The protection effect was improved.