Study On The Strength Of High Speed EMU Powered Wheelset

Wheelset is not only the components for transferring wheel-rail force directly,but also the key components to ensure the safe operation of high speed train.As the continuous improvement of EMU speed,the problem of wheeldset fatigue failure has been attached to great attention.In order to ensure road safety of train,it’s necessary to conduct intensive study on wheel-set fatigue problem.This thesis choose a high-speed EMU power wheel as the research object,following studies were carried out.The maximum equivalent stress of the contact surface is obtained by establishing three-dimensional finite element model of the wheel and axle.The connection strength of interference fit is checked by the permissible stress specified in the UIC 510-5 standard.The stress distribution of the contact surface under two kinds of limit interference is calculated by using the contact stress of the minimum interference.Based on the analysis of calculation results,it is found that the calculation results of the axisymmetric finite element model are consistent with three-dimensional model,axisymmetric finite element model can meet the needs of calculation of the interference fit question of wheel and axle.The fit tightness of wheel and axle is checked by calculating the minimum friction coefficient that meet the transmission requirements.The axisymmetric finite element model for wheel-set press-fitting is established,and the fitting curves of the two kinds of limit interference are obtained through the finite element calculation.In order to check the fit parameter of wheel and axle further,the results of the press fit were judged by using the press-fitting characteristic diagram which EN standard provide.Three different forms of the axle shaft symmetry model are established,which are the straight type,the shaft shoulder type and the sudden suspension type.It is found that the maximum contact stress decreases with the decrease of the suspend length,and suspension assembly will produce a large contact stress on edge of the assort position,which have an effect on delaying the fretting wear.According to EN 13104 standard,the force analysis of the axle is carried out under the mass in motion load,the friction braking load and the dynamic braking load by the theory of material mechanics.And the bending moment and torque produced by three kinds of loads are calculated.The synthetic bending moment diagram of axle was obtained by using Moore’s strength theory.31 axle check sections including all assembly and transition surfaces are selected,through the calculation of the safety factor,the most dangerous section of axle is located at outer edge of wheel seat adjacent to the gear mount.Using three kinds of loads specified by the UIC standard,7 radial sections was selected to carry on the finite element analysis,and the strength evaluation based on static load was carried out.Based on the principal stress method,4 radial sections were selected to calculate the dynamic stress of the wheel web non-hole region,and the fatigue strength was evaluated by Goodman-Haigh fatigue limit method and safety factor method.The applicability of the principal stress method and the multi-axial fatigue method,and the difference between three multi-axial fatigue criteria were investigated by comparing the safety factor of plate hole edge node.