Research On Configuration Optimization On Metro Passive System

Railway transportation is the most suitable transportation mode for China’s geographical features as one of continental countries. And safety, as the core of the entire rail transportation work, is the most important factor to guarantee the operation order, passenger’s life and property, meanwhile it is one kind of comprehensive performance which ensures the cargo and transport equipment in good condition. In order to delivery passengers and goods to the destination fast and safety, the railway transportation security management policy- "safety the first, prevention the first" is carried out to guarantee the transportation safety system in China. It is related to every citizen, so the passive safety system must be reliable and has to be put to the first place in the daily rail transportation.Buffer, used in the joint between one subway car and the next, is one of the main mechanical components in metro train. It has the function to offset the vertical load between the car bodies and ease the impact force in the longitudinal direction. Thereby the damage and destruction to the car bodies along with the components caused by the impact can be reduced. It is obvious that the buffer can release the impact and diffuse the influence on the car bodies. Crush tube, one kind of destructive energy absorbing device, is installed in the subway train tail. It is made of special treated steel tube which has stable yield strength to bears compressive force, while the energy absorption rate can reach 100%. If the train runs in the non-normal operating conditions, such as violent collision or connection speed is greater than normal number, the crush tube will produce plastic deformation to absorb collision impact energy, so that the vehicle’s longitudinal impact load is lower than its own strength to keep staffs and passengers safe.This thesis cites the principles and advantages of one new type liquid gas buffer which developed by our research group. In the case of only putting the buffer absorbing energy into consideration, the cushioning device is simplified to spring and damping system, meanwhile the collision dynamics equation and model of the six-train formation are deduced. With the help of MATLAB, the simulation is carried out to study the response characteristic of collision, obtain the butter damping energy dissipation, maximum stroke and the relationship between buffer energy absorption rate with the speed after six-train collision. And according to practical demand, the suitable buffers can be select reasonably.Due to the limitation of the buffer on energy absorption, one multi stage energy absorbing system is put forward which requires a crushing device that can absorb the energy of next level. This thesis introduces the design principle of the crushing tube and evaluation index in brief. The single degree-of-freedom system of the collision model is set up. When the impact velocity is greater than 15km/h, the energy of the collision cannot be absorbed entire by the buffer, so the buffer shed. Energy is absorbed by the crushing tube. Then the crushing tube is simplified as an inelasticity spring and damping system during the dynamic model is set up. Considering the nonlinear damping of the crushing tube, the nonlinear shock model and equations of the train hitting the wall is established. Then MATLAB is used to solve the nonlinear equation and calculate the shock characteristics response. The relationship between performance of crushing tube and the energy absorption is studied. The optimal state of crushing tube energy absorption is determined through changing the crushing tube damping coefficient, crushing tube influence coefficient and collision speed.