| Vulnerable groups of road users(VRUs)often face a high risk of casualties in traffic accidents due to lack of protection.According to the statistics of the World Health Organization in 2018,the number of deaths caused by traffic accidents per year has climbed to 1.35 million,of which VRU has distributed 54%.China's annual report on road traffic accident statistics showed that in 2017,the number of deaths caused by traffic accidents reached 63,772,of which VRU accounted for 66.72%,and the number of deaths caused by brain injury reached 77.18%.Due to the lack of video information,the traditional accident reconstruction focused on the pedestrian to vehicle impact(firstly impact)and rarely considered the impact of the ground(secondary impact).Therefore,it is of great significance to research on VRU head injury and comprehensive protection caused by traffic accidents in China based on video information.This paper firstly selected 10 VRU traffic accident cases with clear and complete video information and detailed injuries information based on VRU-TRAVi(VRU Traffic Accident database with Video),and used the high-precision accident reconstruction method to reconstructed the kinematics response and head injuries.The reconstruction results showed that the head initial impact position,the air kinematic response,the rotation angle,the landing posture and body parts were all consistented with the video information.The error range of the final position was within 8%.In addition,the VRU head injured regions and severity were consistented with the accident information.Through reconstructed 10 accident cases by the high-precision reconstruction method,the better evaluation indexes for brain injury were selected.They were:HIC15,maximum angular acceleration,MPS and CSDM0.15 respectively.Secondly,taking the front structure parameters,vehicle speed,VRU size and gait as independent variables and head injury indexes were selected based on accident reconstruction as dependent variables,a total of 300 multi-body simulation and 600 finite element simulation were completed based on MADYMO and HYPERWORKS respectively.Then,the multivariate regression models between VRU head injury and vehicle front structural parameters were established through regression analysis.In addition,the validity of the multivariate regression model was verified used simulation sample sets and real accident cases,respectively.The results based on simulation sample sets showed that for firstly impact,there was a certain correlation between the multiple regression model based on HIC15,angular acceleration,MPS or CSDM0.15 and the front structural parameters of the vehicle,and the multiple regression models could predicted at least 83%of the accident cases(the error level is less than or equal toħ1);For secondary impact,the significant relationship between dependent variables and independent variables of the multivariate regression models were general,and only 50%of accident cases had predictive capabilities.The results based on real accident cases showed that the predictive effectiveness of the multiple regression model reached 86.67%and 66.67%for the firstly and secondary impact respectively.Finally,the sensitivity analysis of the vehicle front structure parameters in the multiple regression equation was performed.The results show that for the firstly impact,the most significant front structure parameter that had effected on the VRU head injury was BL,and BCH was the least significant effect on the head injury.For the secondary impact,BLEH was the most significant parameter on the head injury,and BL and BCH were the two parameters that are least sensitive to the effects of the head injury. |
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