Study On The Design And Numerical Simulation Of The Energy Storage Structure Of The Front-end Energy Absorber Of Urban Rail Train

With the rapid development of the city,the population is constantly expanding,and the demand for travel is increasingly huge.Therefore,the load test of urban rail transit is also increasing,and it needs to be updated faster and faster.With the upgrading and development of urban rail transit,its safety problems become more and more important,especially the passive safety technology in the train safety technology.At present,special energy absorbers are usually installed on trains to dissipate collision energy and reduce structural damage and impact caused by collision,so as to protect the safety of life and property.Based on the principle of energy absorption in the process of metal extrusion,a new type of energy absorption structure-ball extrusion energy absorber is designed in this paper,which can improve the impact energy absorption performance of urban rail train.The energy absorber is composed of solid energy absorber tube,hard ball made of special material,anti-climbing plate and mounting plate.In consideration of the strain strengthening,high strain rate and thermal softening effect of the material in the process of impact energy absorption,the ordinary rigid plastic finite element model cannot fully describe it,so the Johnson-Cook model is adopted.Based on the nonlinear dynamics simulation theory and the explicit algorithm of finite element software ABAQUS,the finite element model of the small ball extrusion energy absorber was established,and the impact energy absorption process was simulated.The influences of design parameters such as extrusion thickness,number of balls and friction coefficient of energy absorption tube on the energy absorption process were studied and analyzed,as well as the temperature coupling in the case of friction heat generation.It is found that the absorber has good energy absorption effect and stability in the collision process.(1)In this paper,a new design of extrusion energy absorption structure is proposed.The former cutting tool type is improved by small ball extrusion,and the finite element model of the small ball extrusion energy absorption device is established on the basis of the finite element software ABAQUS.At the same time,the Johnson-Cook model is used to compare the advantages and disadvantages of the small ball extrusion energy absorber with the cutting tool type energy absorber and the small ball extrusion hollow tube energy absorber through the analysis of the simulated data,so as to establish the advantages of the small ball extrusion energy absorber.Then analyze the absorption capacity of the absorber structure under different parameters,the difference of energy absorption,and the stability of the wave.(2)The small ball type extrusion energy absorber has the advantages of strong absorption of collision energy,easy control of peak absorption capacity,controllable energy absorption process and so on.The structural parameters of the small ball extrusion energy absorption device have a great influence on the energy absorption efficiency.The controllability of the impact energy absorption performance can be realized by improving the structural parameters of the small ball extrusion energy absorption device,so as to improve the energy absorption efficiency.In this paper,the number of balls,the extrusion thickness and the friction coefficient of the energy absorption tube are studied.The results show that the larger the number of balls and the thickness of extrusion is not the better,and the friction coefficient does not have a great effect on energy absorption.Four balls were the most stable,and 4mm and 6mm were the most stable.(3)The chip flow of the small ball type extrusion energy absorber is analyzed,which is directly related to the energy absorption process.The increase of chip indicates that the material unit with complete failure will be less,which will lead to the decline of absorption capacity and the reduction of absorbed energy absorption,but the degree of energy absorption fluctuation will be reduced,making the energy absorption process more stable.(4)The coupling temperature was simulated,and it was found that the heat generated by friction was a considerable part,but the existence of thermal softening effect reduced the deformation stress and absorbed energy of the absorber.