| The tread brake is still one of the main forms of braking,metro vehicles is decided by the characteristics of the metro operation metro vehicle need frequent braking,wheel long time work under high temperature and high contact stress state,the test of the proposed to the stability of the wheel,Therefore,it is necessary to analyze the fatigue strength of the wheel during braking,It can be used to improve the driving mode of subway vehicles and optimize the structural parameters of the wheels,and provide reference suggestions for vehicle maintenance.In this paper,the wheel of a subway vehicle is taken as the research object.Based on the thermal conductivity theory,the temperature field and stress field of the wheel are calculated by using the finite element method during braking,and the fatigue strength of the spokes plate of the vehicle is evaluated.The main research work of this paper includes:(1)Mathematical modeling of heat conduction between objects is carried out according to relevant theories of heat conduction,and thermal conduction differential equation is obtained.Study the principle of finite element analysis,establish the connection between thermal conduction and finite element method,combine thermal analysis and finite element analysis organically,provide theoretical support for subsequent wheel transient thermal analysis.(2)The three-dimensional finite element model of subway wheels was established by using the finite element software ANSYS.The initial conditions and boundary conditions for solving the temperature field were set,and relevant parameters such as heat flux and convective heat transfer coefficient were determined for the transient thermal analysis.(3)Simulate the distribution of temperature field and stress field of the wheel under two driving modes of continuous emergency braking and normal operation braking,and judge whether the wheel meets the maximum temperature requirement.The Hertz contact pressure and equivalent stress of the wheel at the highest temperature were obtained from the calculation results of temperature field and stress field,and then the tread damage was evaluated according to the tread damage evaluation criteria.(4)to calculate the new analysis of the subway vehicle wheel by straight line,curve,and when an emergency brake switch three wheel under the condition of stress state,it is concluded that car spokes plate and wheel hub,wheel disk and wheel rim border parts of the area of stress concentration,finally according to the relevant standards to evaluate fatigue strength,car spokes board under the mechanical load and thermal-mechanical coupling load all meet the requirements,But the spokes of wheels are more prone to fatigue failure when there is thermal stress.(5)The stress response of the new wheel and the worn to limit wheel under three working conditions of straight line,curve and turnout during normal operation is compared and analyzed,and the position where the stress value of the worn to limit wheel increases the most compared with the new wheel is determined,that is,the weak area of the wheel.The radial stress of two kinds of wheel spoke plate was extracted,and the Haiigh-Goodman curve was drawn according to the stress calculation results to evaluate the fatigue strength of the wheel spoke plate.Finally,it was found that tire tread wear would lead to the deterioration of the fatigue resistance of the wheel spoke plate. |
PDF Full Text Request