Keywords: rolling-sliding, wear, contact-fatigue, rail-wheel.

Improving the total life cycle costs and safety of trains are current research topics that hold great interest for those who build, maintain and operate trains. The maintenance interval for both wheels and rails has become a major issue for cost reduction while increasing safety. This has encouraged the development of new tools for predicting the evolution of wear and to establish a convenient maintenance schedule. These new tools require the synergy of dynamic analysis and the development of suitable wear models. Rail/wheel wear depends on material properties. Difference in material properties result in competition between contact fatigue and sliding wear mechanisms. Therefore, all the contact conditions affecting the contact stress distribution will govern the wear behaviour. This research paper investigates the effect of contact conditions on the friction and wear behaviour of EN 260 rail steel and R7 wheel steel. A roller-on-roller model was selected to simulate the contact between the wheel (lower specimen) and the rail treads (upper specimen) and, to ensure the compatibility of the results with the real working application. Laboratory simulation used two-disc rolling-sliding tests to study the effect of the creep ratio, contact pressure and the tangential speed on the resulting traction coefficient and the amount of wear. The volume loss was estimated by weighing both specimens before and after the tests. Profilometry, integrating the area of the track wear, was performed to assess the wear on the wheel specimens and to compare and validate the results. Wear volumes were used to develop a wear equation based on Archard's model and considering weighting factors to estimate the influence of creep ratio, contact pressure and tangential speed on the specific wear rate. The predicted results were compared with the results of tests performed in the laboratory. Quite small differences between the predictions and the laboratory tests confirm the reliability of the forecasting method.

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