DEVELOPMENT ANALYSIS OF MAIN DEFECTS AND THEORETICAL FORECAST OF RAIL SERVICE LIFE IN THE CONDITIONS OF LUBRICATION

Abstract

Purpose. The study is aimed at identifying the patterns of the load influence on the rail and the parameters of the two-layer lubrication on the development of the main rail defects, namely, lateral wear in the curved track sections. Methodology. To establish the distribution of the main rail defects by type and sections of the track, expert estimates of the track service of the Azerbaijan Railway were used with respect to the results of measurements of defective parameters and rail service life on individual sections. To establish the load influence patterns and the parameters of the two-layer lubrication on the intensity of lateral wear of the rails and their service life in the curves, we used the main provisions of the contact interaction mechanics, as well as tribology and chemmotology. Findings. The authors proved: 1) the leading rail defects in the curved track sections are defects associated with low contact fatigue strength of steel, high contact stresses and friction forces along the lateral surface; 2) according to the obtained distribution, the main rail defects in the curves should include: lateral wear of the head, metal shelling along the lateral surface, transverse cracks in the head in the subsurface area; 3) the use of a two-layer lubrication leads to an increase in the actual contact area of the wheel and the rail, a decrease in the contact pressure on the rail, and in aggregate, to a decrease in lateral wear and an increase in the rail service life. Originality. The authors first systematized the results of measurements of the rail defects parameters in curves and, on this basis, obtained a distribution of the main defects depending on the curve radius. The authors improved the mathematical model for calculating the service life of rails in curves, which, unlike the existing ones, takes into account the thickness of the lubricating film and the concentration of the solid anti-friction additive in the oil when lubricating the lateral surface. Practical value. The obtained results allow us to perform predictive calculations of the rail service life in curved sections depending on the load from the wheel for different operating conditions, namely, with dry contact of the wheel with the rail and in the conditions of their two-layer lubrication. The implementation of two-layer lubrication in railway transport, taking into account the influence of the studied parameters, will lead to an increase in the rail service life in the curves by 55%, 50% and 45% with an estimated rolling stock mass of 60, 70 and 80 tons.