Study On Head Injury Mechanism Based On Finite Element Model Of A Three-year-old Pedestrian

Road traffic accident is one of the serious factors threatening human life safety.Children’s physical development and limited social cognition make them more vulnerable in road traffic.Due to the influence of various factors,there are relatively few researches on child pedestrian injury at present,and it will be a development trend to study child traffic injury through the finite element model of child pedestrian.Therefore,in this study,finite element method was used to establish two posture models of three-year-old children,namely,standing and walking posture.It is of practical significance to study the impact of different vehicle types,different collision speeds and different standing posture on three-year-old children’s head injury,aiming to provide theoretical basis for child pedestrian protection.In this paper,by referring to the attitude parameters of six-year-old pedestrian and 50 th percentile pedestrian specified in the Euro NCAP’s Pedestrian model certification Technical notice TB024,two finite element models of a three-year-old children’s standing posture and walking postures with detailed anatomical characteristics were obtained by adjusting the sitting model of the three-year-old children.The simulation calculation of human-vehicle collision is carried out in PAM-Crash software.Combining the finite element model of child pedestrian with FCR(Family Car),MPV(Multi-purpose Vehicle and Superminis),Collision simulation tests were carried out for RDS(Roadsters)and SUV(Sport Utility Vehicle)four general models at speeds of 30 km/h,40 km/h and 50 km/h collision speeds.Twelve groups of simulation tests were set up for the finite element model tests of standing posture and walking posture respectively.The data of person-vehicle contact force,head contact force,head centroid synthetic acceleration and brain tissue stress-strain parameters were extracted from the simulation tests were applied to study the influence of four vehicle models on the head injury of three-year-old children’s standing posture model and walking posture model.Under the same speed collision,the head injury of SUV model was the most serious.In the same vehicle collision,the head injury of walking posture was more serious than that of standing posture.The leading edge height of vehicle cover has great influence on the kinematic response of three-year-old pedestrian’s head.In the SUV model test,the WAD value of the head impact position of children with standing posture and walking posture under the three speed tests was 904.1mm and 928.0mm,respectively.In MPV model test,the WAD value of children’s standing posture test remains unchanged with the increase of vehicle speed,both of which are 871.0mm.In FCR,RDS and MPV vehicle tests,the WAD value of children’s walking test increases with the increase of vehicle speed.The WAD value can provide reference for the design position of the head protection device for children pedestrians.In this study,the finite element models of standing and walking postures of a three-year-old pedestrian and four typical vehicle models were used to simulate pedestrian-vehicle collision at three different collision speeds.The research results have significance theoretical and application value for the development of finite element mode of three-year-old children,the study of head injury mechanism of child pedestrian in the process of collision,and the design of automobile front-end structure.