| Pedestrians are one of the most vulnerable road users in traffic accidents,and head injuries are the leading cause of serious injury or death to pedestrians.The types of pedestrian head injury are complex and the evaluation criteria are controversial.Therefore,it is necessary to further understand the mechanism of pedestrian head injury and propose more scientifically based injury evaluation criteria.Pedestrian protection research in my country started relatively late.Most of the relevant laws and regulations were formulated with reference to European and American pedestrian safety regulations.China’s road traffic conditions and human height distribution are quite different from those in European and American countries.my country’s existing laws and regulations may not conform to my country’s national conditions.Therefore,based on my country’s real accident information and simulation reproduction,this paper deeply studies the characteristics and damage risk of pedestrian head-vehicle collision boundary conditions,and provides a scientific basis for formulating pedestrian regulations test conditions and evaluation criteria in line with my country’s national conditions.Firstly,this work selected 57 real world traffic accident cases in China that meet the reconstruction conditions and analyzed the basic information of the accident cases.The results show that the vehicle collision speed in 77%of the accident cases is in the range of 26-55km/h,and the average collision speed is 44km/h;the average height of female pedestrians is 157cm,and the average height of male pedestrians is 170cm,which basically matches the Chinese anthropometric parameters.Then,57 real accidents were reconstructed by multi-body dynamics simulation,and the accuracy of the reconstruction results was verified.Then,pedestrian head-vehicle collision boundary condition parameters in the accident reproduction were extracted,the characteristics of the boundary conditions of pedestrian head-vehicle collision were analyzed,and the influence of different collision boundary conditions on the dynamic response of the pedestrian head was studied based on finite element simulations of head-windshield and head-bonnet collisions.The results show that:67%of the accident cases have a linear head collision speed in the range of 26-45km/h,and a head rotation collision speed in the range of 21-40rad/s;58%of the accident cases have a head collision time in the range of80-140ms The time of head collision is generally earlier than 140ms;70%of the accident cases head collision angle is in the range of 40-70°,the average is 53°;61.4%of the accident cases head collision position is on the windshield,The windshield is the main collision position of the pedestrian’s head;the WAD is in the range of 1.5-2.3m,and its average is 1.8m;my country’s current regulatory test standards cannot cover 80%of the accident samples;the head collision position is different from the collision vehicle The pedestrian head-vehicle collision boundary conditions are significantly different;the head rotation motion has a significant impact on the head dynamic response and injury risk.Finally,the dynamic response parameters of pedestrian head-vehicle collision in accident reproduction were extracted,the numerical values of different head damage dynamic evaluation criteria were calculated,the injury risk curves were constructed and correlation analysis was carried out.The results show that the thresholds of the head injury evaluation criteria HIC,HIP,GAMBIT,RIC,Br IC2011 and Br IC2013 corresponding to the 50%AIS3+head injury risk probability were 1300,60k W,0.74,1470×10~4,0.56 and 0.57 respectively;the predictive power of injury risk curves established based on HIP(AUC=64.8%)and Br IC2013(AUC=73.7%)is lower than other injury criteria;GAMBIT,RIC and Br IC2011 can be Considered as a potential addition to the HIC for pedestrian head injury assessment. |
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