Experiment Aland Numerical Study On Rail Wear Characteristic

As an important component of wheel/rail system, steel rail plays an important role in of the development of high-speed and heavy-haul railway transportation. However, as the derailment, vibration and other problems of trains caused by friction and wear, such as rail fracture, corrugation, crushing and fatigue crack propagation, have led to great losses of manpower and materials. The friction and wear of steel rail has become a main restricting factor for the development of railway. Therefore, it is of important economic and realistic significance to study the wear mechanism and factors of steel rail to decrease its wear rate and prolong its service life.In this paper, experimental methods of both micro-scale and macro-scale were used to investigate the mechanical and triboloigical properties of rail materials. Numerical calculation was also conducted using Kalker’s non-Hertzian rolling contact theory of three dimensional elastic bodies, aiming to provide a theoretical basis for the wear prediction of steel rail based on friction work. Based on the experimental data and the results of calculation, the wear volume formulas of steel rail were explored by means of friction work of rail-wheel and PLS. Main conclusions were drawn as follows:(1) The tribological behavior of steel rail depended strongly on its mechanical properties. Owning lower hardness, lower intensity, and U71Mn rail material exhibited poorer wear-resisting performance compared to PD3rail material.(2) There exist a linear relation between the wear loss of rail and the axle load of trains. With curve radius and train speed increasing, the wear rate of rail reduced nonlinearly. The wear rate changed rapidly especially when the speed was no more than160Km/h and curve radius less than1200m.(3) As the number of cycles increased, the wear volume of steel rail increased linearly, while the wheel exhibited a nonlinear increase in the wear volume. And the increase rate of wear volume was higher for wheel than for steel rail. Compared with PD3rail, a wear scar with bigger width and depth and uneven surface appeared on the surface of U71Mn rail.(4) With the increase of y, φ andφ, the adhesion/slip area equivalence point of the contact zones of rail/wheel moved forward the direction where lateral displacement reduced. But the point moved forward the direction where lateral displacement increased with the increase of friction coefficient. For sliding condition, the maximum value of normal stress, equivalent stress, plastic strain, and shear stress, were observed in the surface layer where the damage of wheel/rail material easily occurred under the action of mechanical loading.(5) Based on the experimental data and the results of numerical calculation, empirical equations of the variation of the wear loss of steel rail versus axle load, curve radius and wheel speed were established by means of friction work of wheel-rail and PLS respectively. The equations would be helpful to further studies on the wear of wheel/rail and the prediction of rail’s wear volume of both in the laboratory and in the field.