Thermal-mechanical Coupling Analysis Of Train Brkae Disc Based On ADINA And Experiment Validation

In high speed train braking,the friction pair is subjected to high heat load and alternating stress,which is easy to cause the heat fade of friction material and the thermal fatigue damage of the brake disc,which is a threat to the safety of the train.Braking condition decides the braking energy and the heat input power,is a key factor to affect the temperature of the brake disc;the material parameters affect the distribution of contact pressure and heat flux in the friction pairs,which can also affect the temperature of the brake disc.Therefore,the study of the influence of the braking condition and the material parameters on the temperature field and the stress field of the brake disc is of practical significance to improve the safety operation of the train and the development of the friction pair.In this paper,a thermal-mechanical coupling finite element model including brake disc and pad of TM-I rail train shrinkage test bench for braking based on ADINA solftware is established.Using this model,the temperature field and stress field evolution law of the braking process are simulated,the effects of brake pressure and initial velocity on the temperature field and stress field of the brake disc are discussed,the relationship between the contact pressure and the temperature of the brake disc under different pad material parameters is analyzed.Carrying out the braking test under different conditions,this paper study the change law of the temperature field on the surface of the brake disc during braking,and compare and analyze the difference between simulated temperature and measured temperature.The results showed:(1)Under different braking conditions,the temperature field and the stress field on disc surface distribute in a circular strip,the peak temperature and the peak stress increase linearly with the increase of the brake initial velocity and the brake pressure,under brake pressure 0.538 MPa,when the brake initial velocity increase from 100 km/h to 250 km/h,the peak temperature increase by 426.1 ℃,the peak stress increase by 564.3 MPa;under the initial braking speed 100 km/h,the brake pressure increase from 0.236 MPa to 0.538 MPa,the peak temperature rise by 20.9 ℃,the peak stress increase by 37.1 MPa.(2)The pad thermal expansion coefficient has the most obvious influence on the temperature and the contact pressure of the brake disc.Due to the uneven distribution of the contact pressure is increased obviously with the increase of pad thermal expansion coefficient,the brake disc temperature is changed obviously;when the elastic modulus increases,the peak temperature and maximum contact pressure are basically unchanged,the distribution of the contact pressure is not sensitive to the elastic modulus,and the elastic modulus has little effect on the temperature of the surface of the disc.The heat diffusion increases with the heat transfer coefficient increases.which can lower the peak temperature of the brake disc:the increase of specific heat reduse the heat flux entering into the brake disc and lower the peak temperature of brake disc.(3)The degree of agreement between simulated temperature distribution and measured results depends on the actual contact state of the pad and disc,under the braking condition of low speed and low pressure,because the pad and the disc is not fully fit,resulting in the radial temperature curve is flat in the early stage of braking,under the braking condition of high speed and high brake pressure,due to the cumulative wear of brake disc in previous braking process,A groove is formed in the middle part of the friction region,resulting in the local contact between the disc and pad in the early stage of braking,two narrow high temperature zone formed on both sides of the friction zone,along with the braking process,wear of the firction pair improves the contact condition between the disc and pad,which is close to the ideal contact condition of numerical simulation,and the numerical simulation results reflect the change of the theoretical temperature.(4)The comparision between simulated pad temperature and measured one results:measured temperature of the brake pad is much higher than that of numerical simulation;with the increase of the brake pressure,the temperature difference becomes larger,with the increase of the brake initial velocity,the temperature difference firstly increased and then decreased,this is because the thermal resistance between the disc and pad is not considered in the numerical simulation,and the influence of the heat transfer between the brake pad and the connecting part is ignored.