| With the development of China's economy,high-speed railway also conform to the situation has been greatly developed.As the speed of the vehicle continues to improve,security is also a matter of concern.Wheel-rail adhesion problems become more prominent as the speed increases.In order to ensure the safe operation of the train it is necessary to carry out research on the mechanism of high speed wheel and rail adhesion from the theoretical and experimental point of view.In this paper,through the establishment of three-dimensional high-speed wheel-rail adhesion numerical model and carry out high-speed wheel-rail adhesion test to reveal the existence of oil and gas pollution on the surface of the adhesion mechanism,the main conclusions are the following three conclusions.1.The numerical model of three-dimensional high-speed wheel-rail adhesion considering the thermal effect is established.The solid pressure is modeled by the Zhao-Maietta-Chang(ZMC)model,which is consistent with the elastic-plastic deformation of the wheel-rail material,and is compared with the Greenwood-Tripp(G-T)model.At the same time,the pressure distribution of the wheel/rail interface was obtained and the influence of the factors such as speed,axle load and roughness on the adhesion coefficient was investigated.It was found that the adhesion coefficient decreased with the increase of the velocity,and the film thickness increased.Axle load has little effect on wheel and rail adhesion.The roughness has a significant effect on the adhesion coefficient.2.According to the roughness test results of the locomotive wheel,the radius of the roughness is within 50?m by Fourier fitting analysis.Using the ANSYS model to establish a single rough and rigid plane contact,the demarcation points of the elastic-plastic deformation of the model are found,and the empirical formula of the contact between the single rough and the rigid plane is fitted.And with Kogut-Etsion(KE),Jackson-Green(JG)model.Then,the contact of a single roughness is extended to contact with the rigid plane,and the corresponding empirical formula is deduced and compared with the KE and ZMC models.Focusing on the average gap,the real contact area and contact pressure distribution.The results show that the average gap,the real area and the contact pressure distribution are close to those of the KE and ZMC models,and the maximum contact pressure of the contact pressure distribution is smaller than that of the other two models.The area distribution is larger than the other two models,This rule is consistent with the true contact area versus load.The numerical results also show that the fitted empirical formula has nothing to do with the roughness radius and the yield strength,so the empirical formula can well simulate the calculation of the elastoplastic contact pressure of the wheel and rail.3.The high speed wheel-rail adhesion test was carried out by using the high-speed fatigue machine of the State Key Laboratory of Traction Power of Southwest Jiaotong University for dry state,water medium,oil pollution and water and oil mixture.The maximum speed reached 200 km/h.By controlling the size of the pump flow simulation of the actual heavy rain and light rain situation.The change of adhesion coefficient in the presence of different pollutants at high speed was investigated,and the influence of axle load was considered. |
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