Research On Energy Absorption Characteristics And Optimization Design Of The Expansion Tube Buffer

With the speeding up of trains, the study of passive safeguarding for the trainbecomes particularly important. Working reliably, being easy for processing andadjustment, as a part of the passive safety protection system, the expansion tube buffer isused in coupler buffer device to buffer and absorb energy. At present the amount ofdomestic high-speed trains is growing, the demand for tube expansion buffer is increasing.Facing the entire coupler buffer devices in use in China are purchased from Europeanmanufacturer, it is significant to research on tube expansion buffer and apply the researchachievement into production. Given such a situation, this paper studied the energyabsorption characteristics and optimization design of tube expansion buffer by theoreticalderivation, computer simulation and tests, which might help to accelerate the manufactureof tube expansion buffers in China.At first, this paper will carry out a quasi-static compression test of tube expansionbuffer which intends to study the effect of the expanding, wall thickness and cone angle tothe energy absorption characteristic of tube expanding buffer. The test results also areused to verify the accuracy of theoretical model and numerical simulation in chapter3andchapter4.Secondly, as there is much deviation between the calculation of the existing crushingforce mathematical model and the real situation, and the existing crushing force formula,other researchers deduced, without considering the effect of the bend of tube. This paperdeduced the crushing force mathematical model which considered the effect of the bend oftube. And compared with experiments, we can found that crushing force theoretical modecan’t direct practical application.Thirdly, simulations of the experiment cases are carried out by ANSYS/LS-DYNA.Comparing the simulations with experiments, it can be found that the crushing force-displacement curves got from the simulations are very similar to those got from theexperiments, which proves the simulations can direct the design of tube expansion buffer.And using simulations to study the effect of velocity to the crushing force-displacement curves, it can be found that the velocity has little effect on the size of crushingforce-displacement curves, and has no effect on the shape of those, which certifies thatconducting the quasi-static compression test of tube expansion buffer can be apractice guidance.Lastly, the simulations of expansion tube buffer, having expanding-preformed section,to study the optimized design of structure have been performed. And the simulationsresults proves that for a fixed inside diameter and a fixed wall thickness, there is a fixedexpanding size to maximize the energy absorption efficiency, and for the tubes who havethe same inside diameter, when the wall thickness is larger, the expanding size should belarger to approve the ideal energy absorption efficiency. These conclusions point out thedirection for optimization design of tube expansion buffer.