Secondary Collision Injury Of Train Occupants And Interior Table Protection Design

In rail train collision accidents,the life safety of passengers is threatened by secondary collision seriously.It is the basis to reduce the occupant injury by clarifying the mechanism of occupant injury in the secondary collision process and carrying out effective passive safety protection design.The rail train is not equipped with special safety protection equipment,and the occupants lack of buffering process in the secondary collision in the accident.Therefore,it is of practical significance to propose safety protection measures with simple structure,reliable performance and maintainability to guide the occupant’s movement posture and avoid fatal injuries.In this paper,the assessment of train occupant safety damage is focused,optimization of interior table parameters,and structural design of energy-absorbing table panels to study measures to reduce occupant secondary collision damage.Specific studies are as follows:(1)Assessment of occupant secondary collision injuries.The internal crash scenarios are constructed by using a simplified local model of the train car and the LSTC Hybrid III 50 th percentile seated dummy model to assess the occupant head,neck,chest and leg injuries using GM/RT2100 and APTA SS-C&S-016-99 standards,respectively,and to analyze the occupant secondary crash injury mechanisms under different standard loads.(2)Optimize the dimensional parameters of the interior table panel.Using the physical parameters of the table board as design variables,a three-factor and five-level orthogonal test is designed to study the influence law of each variable on occupant head,neck,chest and leg injuries;the Kriging agent model is used to establish the relationship between the size parameters of the interior table board and the neck injury criterion and comprehensive injury index;the NSGA-II algorithm is used to solve the optimization problem of the table board parameters and to verify the optimization scheme.(3)A honeycomb sandwich table plate with gradient wall thickness is proposed to reduce occupant damage as the energy absorption perspective.The geometric configuration of the sandwich is designed with reference to the honeycomb structure and the leaf vein structure,and the total energy absorption,specific energy absorption and average crush load of the structure are obtained through the simulation analysis of the lateral crush of the energy absorbing sandwich.The optimal Latin hypercube design is used to sample the wall thickness gradient parameters.The polynomial response surface model is established from the crashworthiness index and the wall thickness gradient parameters.The gradient wall thickness sandwich structure is optimized with the maximum total energy absorption and specific energy absorption and the minimum mean crush force,and the optimal gradient parameters are obtained by using NSGA-II algorithm.In this paper,from occupant injury assessment,the injury location and injury mechanism of the dummy is researched,and propose two occupant protection measures: optimization of table size parameters and energy-absorbing table plate.Both measures change the occupant’s motion posture during the collision,avoid contact between the head and the table directly,and significantly reduce the occupant’s injury.The feasibility of the protection measures is high and has some practical significance.