Study On Head-Car Body Crashworthiness And Sitting Occupant's Injury In A Subway Collision

With the rapid development of cities in recent years,traffic congestion is more and more serious.Based on the advantages of large capacity,convenience and quickness,the subway gradually becomes the preferred way to travel.However,because a subway train consists of multiple cars and there are lots of occupants,once a collision accident happened,many people may get seriously injured.Therefore,with the improvement of subway cars' active safety at the same time,it is of great significance to study the crashworthiness of subway cars.With the subway head-car body taken as the research object,firstly,the secondary factors such as interior equipment were ignored according to head-car response in the collision,and the models of head-car body,coupler drift gear and anti-climber were established in Solid Works.Then,in accordance with the amount of energy absorbed by each part of head-car,the density of the finite element mesh is determined and the meshing is finished by using Hyper Mesh.Secondly,numerical simulation of a subway head-car at the speed of 25 km/h impacting a same kind head-car at rest was accomplished by using LS-DYNA.The result shows that the maximum deformation of cabs is 3.73%,the maximum reduction in length of vehicles' compartment is 18 mm over 5 m length,the maximum value of mean longitudinal acceleration in survival spaces is 4.64 g,which all meet the needs of the European standard EN15227.Thirdly,the subway seat's finite element model was developed,and by taking the speed of the seat which is nearby self-motion head-car's first side window during the collision as boundary condition,the posture responses of sitting dummy near side backup and in the middle of longitudinal seat during secondary collision were simulated separately.The result shows that 3ms acceleration of chest and maximum tibia index of the occupant sitting in the middle of longitudinal seat reach 70.81 g and 0.60 respectively.Comparing them with the abbreviated injury scale and C-NCAP presents that the occupant's chest will get serious injuries,such as multiple rib fractures,hemothorax,pneumothorax and flail chest;and the legs may be subject to some damages.But the occupant sitting near side backup may be slightly injured or not injured.So subway head-car occupants should give priority to be seated near side backup.Finally,to reduce the injury of occupants siting in the middle of longitudinal seat,the armrest installed in the middle of seat is considered and verified by numerical simulation.Result shows that compare with before,the occupant's chest 3ms acceleration and maximum tibia index declined by 83.7% and 43.3% respectively,and the occupant isn't injured.Because armrests can reduce occupants' injuries effectively,so they are proposed to be installed in the middle of longitudinal seats of subways.