Study On The Head Injury Of Cyclist Based On Real Bicycle Accident Reconstruction

As an economical and convenient means of transportation,bicycles are an important way for people to travel.With the boom of bike-sharing in the past two years,by the end of 2017,the number of bike-sharing in China had exceeded 25 million,covering more than 200 cities.Massive use of bicycles leads to a series of bicycle traffic safety issues now,especially car and bicycle traffic accidents.Compared with cars,bicycles have poor stability and lack of effective protective devices,making it more prone to accidents causing casualties and economic losses.Head injury accounts for the largest proportion of total injuries in various parts of the body in traffic accidents,which is the main cause of death.Therefore,it is very necessary to carry out research on head injury of cyclists.This paper aims to study the mechanism of craniocerebral injury of cyclists in car-bicycle collision accident,and explore the research on the risk of head injury of cyclists caused by the change of windshield Angle and different head collision speeds.Firstly,it introduces the deep investigation system of traffic accidents.Secondly,it summarizes the damage mechanism,tolerance limit and evaluation criteria of the human head.Established and validated the head biomechanical model based on the 50 th percentile body size in China.Thirdly,based on the depth investigation of traffic accidents,a real car-bicycle collision with video images is selected.It carried out PC-Crash multi-rigid body simulation accident reconstruction.The kinematic response of the collision between the car and the cyclist is reproduced through the final position of the vehicle,the bicycle and the cyclist as well as the movement posture of the cyclist during the collision.Compared with the actual accident situation,the simulation results show good consistency,which verifies the reliability of the simulation method and model,and calculates the initial speed of the collision between the cyclist's head and the windshield.The simplified finite element model of head-impact windshield was built by Hyperworks software,and the simulation results were calculated by LS-DYNA solver.The injury was evaluated by head impact contact force,peak acceleration,HIC value and pressure distribution in the brain.The results show that the collision simulation finite element model can effectively reproduce the damage crack of windshield during the accident.The results show that the collision simulation finite element model can effectively reproduce the damage crack of windshield during the accident.Since the HIC value is much smaller than the head tolerance limit of 1000,and the intracranial pressure distribution is also within the limit range,this indicates that the head is not subject to obvious fatal damage during the collision of the head with the windshield.The reason for the death of the cyclists is due to the secondary collision between the head and the ground.The change of windshield installation angle and head collision speed has a significant impact on the risk of head injury of cyclists.Reducing windshield installation angle and head collision speed over 40km/h will increase the risk of head injury of cyclists.On the one hand,the research of this paper can provide data support and technical reference for the passive safety improvement of automobile,and on the other hand,it can provide reference basis for the traffic safety department to prevent and reproduce accidents.