Modelling of Frictional Conditions in the Wheel–Rail Interface Due to Application of Top-of-Rail Products

Abstract

The coefficient of friction between a wheel tread and the top of the rail should be maintained at intermediate levels to limit frictional tangential contact forces. This can be achieved by applying top-of-rail products. Reducing the coefficient of friction to intermediate levels reduces energy consumption and fuel costs, as well as damage to the wheel and rail surfaces, such as, e.g., wear, rolling contact fatigue, and corrugation. This work describes a simulation model that predicts the evolution of the coefficient of friction as a function of the number of wheel passes and the distance from the application site for wayside application of top-of-rail products. The model considers the interplay of three mechanisms, namely the pick-up of product by the wheel at the application site, the repeated transfer of the product between the wheel and rail surfaces, and the product consumption. The model has been parameterized with data from small-scale twin disc rig experiments and full-scale wheel–rail rig experiments. Systematic investigations of the model behaviour for a railway operating scenario show that all three mechanisms may limit the achievable carry-on distance of the product. The developed simulation model assists in understanding the interplay of the mechanisms that govern the evolution of the coefficient of friction in the field. It may aid in finding optimal product application strategies with respect to application position, application amount, and application pattern depending on specific railway operating conditions.

Mechanical Wear Contact between the Wheel and Rail on a Turnout with Variable Stiffness

“…The magnitude of the occurring wheel-track contact forces plays a decisive role. Of course, wear of the rails is accompanied by wear of the rims ( Figures 38,40,42,43,46 and 47). In the presented wear diagrams, the distances between minima and maxima are within 2-3 m, while the distance between axles in the bogie is 1.9 m. The maximum lateral wear occurs at distances of 6-9 From the presented simulation results, it can be clearly seen that the wheel and rail wear when passing through a turnout is many times greater than on a track without a turnout.…”

“…The development of turnout constructions also results from technological progress in the production of new steel grades for railway turnouts, the development of new material testing methods, and a better understanding of the phenomena occurring in wheel-rail interaction [43][44][45][46][47][48].…”

Validation of a Physics-based Prognostic Model with Incomplete Data

“…The distribution is assumed to be a nor-mal distribution, where the minimum and maximum values of the input parameters represent all possible values that can occur in practice. For example, a wide range of friction coefficient values is given in Table 1 because the friction in wheelrail contact depends on several operating environmental factors such as the ambient temperature, atmospheric humidity, rail surface condition, friction modifiers, water, sand, grease (lubrication), contamination, leaves, leaf mulch and water with iron oxides and wear debris (Trummer, Lee, Lewis, & Six, 2021;Rong et al, 2021).…”

Towards a Standard Approach for the Twin Disc Testing of Top-Of Rail Friction Management Products

“…Amounts should be scaled to take account of the smaller contact sizes being used in the tests. It is relevant to look at different amounts as carry-down mechanisms mean that the amount of product on the rail head changes with distance from the application point (see Figure 9 [23]). Another issue is the misapplication of water-based TOR-FMs.…”