Research On Accident Reconstruction Optimization And Damage Simulation Of Electric Two-wheeled Vehicles For Cyclist Protection

Electric two-wheeled vehicles are an important means of transportation for short-distance travel in urban and rural areas in China.As of 2021,the number of social vehicles has reached nearly 340 million.As the number of electric two-wheeled vehicles increases and their mobility becomes powerful,thus the accidents of electric two-wheeled vehicles are also increasing year by year,so it is necessary to conduct in-depth research on the safety of electric two-wheeled vehicle cyclists.In order to explore the general rules of electric two-wheeled vehicle accidents and reduce the risk of injury to cyclists,this article,based on in-depth investigation of accident cases,conducts reconstruction optimization and collision simulation for electric two-wheeled vehicle accidents based on multiple injuries of cyclists,and deeply explores the potential factors that affect the severity of injury to electric two-wheeled vehicle cyclists,which has a positive impact on the protection of electric two-wheeled vehicle cyclists and the structural optimization of electric two-wheeled vehicles.Provide theoretical basis and suggestions for the traffic management department to formulate and revise relevant management measures.This paper first summarizes the research process and content of the in-depth accident investigation,screens out 742 car-electric two-wheeler collision accidents based on CIDAS data,and summarizes the characteristics of electric two-wheeler accidents and personnel injuries through descriptive statistical analysis.Secondly,in order to explore the potential heterogeneous effects of accidents,Ordered Probit Model(OPM),Random Parameter Ordered Probit Model(RPOPM),and Correlated Random Parameter Ordered Probit Model with Heterogeneity in Means(CRPOPMHM)were used to model the severity of injuries to electric two-wheeled vehicle cyclists,and to explore the heterogeneous of random parameters and their correlations that affect the severity of injuries to cyclists.Establish a generalized additive model(GAM)to explore the nonlinear effects of continuous variables on the severity of cyclists’ injuries and their interactions,which provides key characteristic variables for further simulation research.Thirdly,in order to improve the accuracy of accident simulation and reconstruction,PC-Crash software is used to reconstruct a real electric two-wheeled vehicle accident case based on a multi-rigid body model.Orthogonal experiments are conducted to screen the parameters that have a significant impact on the accident simulation and reconstruction results.A BoxBenhnken test is designed,and a response surface approximation model is established based on the test results to obtain the optimal reconstruction parameter combination.On this basis,using NSGA-Ⅱ algorithm to optimize parameters for multi-objective optimization,the effectiveness and accuracy of accident simulation results based on multi-rigid body models are verified.Finally,based on the results of the econometric model research,a simulation crash test was constructed to explore the impact of impact location,vehicle speed,and structural parameters of the electric two-wheeled vehicle on the injury of the electric two-wheeled vehicle cyclist,combining the head HIC value,chest 3ms composite acceleration value,thigh and calf shear stress and other cyclist injury evaluation indicators.The results show that:(1)Based on the analysis results of the CRPOPMHM model,it is found that in car-electric two-wheeled vehicle collision accidents,factors like the cyclists are female,young,tall,collide with cars,collide with non-intersection roads,asphalt roads,night time and frontal collisions will make the cyclists less injured in the accident.The variable collision vehicle is SUV and the collision part has random parameter characteristics at the rear.The variable non intersection and night time significantly affect the mean value of the random parameters of the variable collision vehicle type SUV,and there is a significant positive correlation between the unobserved heterogeneity of the random parameters of the variable collision vehicle type SUV and the variable collision location at the tail;Based on the analysis results of the GAM model,it is found that the wheelbase,seat height,distance from the center of the saddle seat to the handlebar,and vehicle speed of the electric two-wheeled vehicle have nonlinear effects on cyclist injury,and there is an interaction between wheelbase and vehicle speed,seat height and vehicle speed.(2)Through the orthogonal test,it is found that parameters such as vehicle collision longitudinal angle,car speed,car driver’s reaction time,and electric two-wheeler speed have a great influence on the simulation results,and can be adjusted in priority during the simulation process;design Box-Benhnken Test and build a response surface approximation model to obtain the optimal combination of vehicle collision longitudinal angle,car speed,electric two-wheeler speed,and driver reaction time,and use the NSGA-Ⅱ algorithm to perform multi-objective optimization of the optimization parameters,the highest accuracy parameter combination for the accident simulation and reconstruction case in this paper was obtained.The reliability of the optimization method was verified by combining the cyclist injury.(3)Through simulation and reconstruction,it is found that compared with a car,the cyclists’ head,chest and thigh injuries are more serious when an electric two-wheeler collides with an SUV,while the calf injury is relatively mild;in a side collision,the legs of the cyclist usually suffer more serious injuries;when the speed exceeds a certain speed,the head of the cyclist will not collide with the front structure of the car,but will collide with the ground.When controlling the speed of an electric two-wheeled vehicle below 30 km/h,it can significantly increase the vehicle speed at which the injury index reaches the threshold,which is more conducive to protecting electric two-wheeled vehicle cyclists.The larger the wheelbase of an electric twowheeled vehicle,the lower the severity of injury to the cyclist in an accident,and the higher the seat height.Compared to the lower severity of injury to the cyclists’ head,chest,and thigh in a car collision,the lower the severity of injury to the lower leg is in the opposite trend.For SUVs,the severity of chest and thigh injuries for cyclists will significantly increase.