A Study On Cyclist Head Response Based On An Electric-bicycle To Motor Vehicle Accident Reconstruction

In China,electric-bicycles have become one of the most common travel methods,but the number of casualties caused by electric-bicycle accidents remains high.Compared with vulnerable road users such as pedestrians,there are currently no regulations and protection protocols applicable to electric-bicycle cyclists,especially the heads of cyclists.An electric bicycle-motor vehicle side impact accident was reconstructed based on MADYMO and LS-DYNA software,and head injuries of the cyclist were analyzed.MADYMO was used to build a multi-body accident model,which reproduces the accident process and obtains dynamic response of the cyclist.The finite element model of head-windshield impact was established by LS-DYNA.The boundary condition of the cyclist head obtained by multi-body accident re-construction was taken as its initial input,and the biomechanical response and damage mechanism of the head were calculated and analyzed.The simulation results are basically consistent with the records of the on-site investigation and the actual damage of the deceased,that means the results of the accident reconstruction are effective.It shows that collision with windshield is the main source of damage to the cyclist.Moreover,the higher dynamic response of skull and brain tissue leads to a higher risk of skull fracture and subdural hematoma in the head of the rider,which may be the main cause of his death.This model has been validated to further investigate the head injury of cyclists and the protective performance of the helmet in electric bicycle-motor vehicle accidents.This model has been verified by accident reconstruction.It could be further based on data mining and decision tree algorithm multivariate parameterized research methods,using an automated modeling and analysis platform mode FRONTIER to build massive different electric-bicycle to car accident conditions,to study the effects of factors such as the cyclist’s body size,the velocity of the electric-bicycle,the velocity of the car,the angle and position of the collision between the two on the head injury and dynamic response of the cyclist,and thus a prediction model of the head response of the electric-bicycle cyclist was obtained and verified.The analysis of the results of the data set shows that: 1.In the E-bike-to-car accidents,the average head impact relative velocity and WAD(Wrap around distance)of head impact location are higher than those in the car-to-pedestrian accidents;2.The velocity of the car is the most critical factor affecting the response of the cyclist ’s head.The higher the velocity,the greater the dynamic response of the cyclist ’s head and the more serious the injury;3.The collision angle between the electric-bicycle and the car and the size of the dummy have a significant impact on the collision area of the cyclist ’s head,and different sizes of dummy suffer different injury in the accident;4.The effects of initial E-bike impact location on the WAD of cyclist’s head impact location is not significant when initial E-bike impact location is concentrated in the region of 0.25 m around the centerline of the car.The prediction model can guide the establishment of relevant regulations or protection protocols applicable to the head of electric-bicycle cyclists.The accident reconstruction guidelines obtained from the decision tree model will help to carry out the reconstruction of electric-bicycle to car accidents.