Research On Biomechanical Damage Of Head And Neck Of Electric Bicycle Rider In Crash Accident

With the continuous increase of the number of electric bicycles in China,the traffic accidents related to electric bicycles are also increasing.Head and neck injuries of bicycle drivers account for about 1/3 of the total number of injuries in vehicle-to-vehicle crashes,therefore,the injuries of head and neck of cyclists should be focused on.The finite element head and neck model can provide a fine model of complex head and neck structure,which can better understand the damage mechanism between the head and neck of a rider and the cranium,cervical spine and spinal cord.Firstly,based on the analysis of human neck anatomy,referring to Hybrid III dummy neck model and a large number of medical literatures,the models of cervical spine,intervertebral disc,ligament and spinal cord of impact dummy were established.The established geometric model of neck was rationalized by meshing.On this basis,a finite element head and neck model is formed by combining it with the original head model of the subject team for further research.Generally,MATL＿77 material was used to simulate the neck muscle tissue in finite element simulation.However,due to the complexity of MATL＿77 material,the simulation time was too long.In this paper,MATL＿27 is used instead of MATL＿77 for neck simulation experiment.First,the stress-strain curve of rubber sample is obtained by compression test,then the curve obtained is fitted in Origin by Mooney-Rivilin rubber constitutive model,and the values C₀₁ and C₁₀ in the model are obtained.Finally,in HYPERMESH,the compression simulation experiment of rubber sample with the same size is carried out.By comparing the two curves obtained from the experiment with those from the simulation,it is found that there is little error,which proves the reasonableness of rubber material parameter setting of finite element and then the subsequent experiment is carried out with relevant parameters.Subsequently,the established finite element model of cervical spinal cord was validated with Maiman,Li and Hung classical spinal cord experiments respectively.In order to verify the rationality of the equivalent neck model,a compression experiment of the neck model was designed.The pressure in the main neck damage index was used as the verification index,and the trend of the experiment and simulation curves were consistent.Finally,referring to Nahum body experiment,the head of head and neck finite element model is impacted by impact block to verify the rationality of the established head and neck finite element model.1757 sets of accident data of electric bicycles in Shandong Province from 2018 to2019 were obtained from the database of the Institute of Forensic Identification.Effective information contained in the accident investigation report includes basic information of both parties and their vehicle injuries,as well as information on road conditions,number of casualties,time distribution,causes,locations and forms.Based on this,statistical investigation is carried out to obtain the road traffic accidents in Shandong from 2018 to 2019.The casualties of two-wheel drivers are analyzed with statistical results.Accurate traffic accident reduction directly affects the reconstruction of head and neck injuries at the rear.They are interlinked,so it is necessary to establish high-precision accident reduction simulation.Based on multi-rigid body dynamics method,this paper uses MADYMO software for accident reduction.In restoring,the instantaneous speed before vehicle collision,distance between person and vehicle after collision and the instantaneous attitude of two-wheel electric vehicle driver before collision are adjusted repeatedly according to video monitoring in accident investigation report in order to achieve more accuracy.Through subsequent animation display in HYPERVIEW,the coincidence between simulation and real accident at several critical time points effectively proves the high accuracy of accident recovery.Afterwards,a corresponding three-storey front windshield finite element model was established according to the accident vehicle.Based on the finite element analysis,the equivalent stresses in the neck and spinal cord from the HIC value of the head and neck of a bicycle driver were determined to be severely damaged.This study has great practical significance for the development of automobile safety industry and traffic injury prevention and treatment in China by establishing a human head and neck model and carrying out reducing and injury analysis work based on traffic accidents to understand the mechanism of action of traffic injury.