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1. Introduction
In the modern track structure, the requirements on rail performance are increasing as they are expected to have high resistance to wear, fatigue, brittle fracture and compression. In addition, rails are required to have good surface quality, good observance of profile and low residual stress for safe, comfortable and sustainable passenger and rail freight operations (Lichtberger, 2005). In contrary, the loading condition of railways is increasing with faster, longer, more frequent and heavier train operations. For instance in Sweden, the iron ore train is 750 m long and approximately 25 per cent of these trains on the southern loop of the heavy haul line travels with an axle load of 32.5 metric tonnes, i.e. 8.3 per cent heavier than the nominal axle load. Undoubtedly, rails could be more susceptible to surface and subsurface damage being the contact point on the track directly bearing this increasing loading profile. Rail wear is of great interest since it is known to be an important degradation mode that can limit the performance of rail, reduce its life span, cause failure of other elements and significantly increase track life cycle cost if not well managed.
Wear occurs at any section on the track, however, the rate and pattern in curved section could be highly unpredictable and alarming without proper insight and proactive measures. This is due to increased lateral force from apparent outward force as a fleet of heavy or fast wagon attempts to negotiate through the curve. This leads to alteration of the stress magnitude and pattern, shift of the contact band on the rail, and increased abrasive wear of the rail by the wheel (Lewis and Olofsson, 2009).
The study of rail behaviour with focus on loss or displacement of material under heavy axle load and high speed operation is often carried out using dynamic simulation tools, test experimentation (site or laboratory), finite element calculation tool, field monitoring, statistical models and hybrid models. Some parametric models have been developed for the estimation of rail wear under some specific operating conditions and loads.
However, the operating dynamics and environmental conditions of railway lead to varying co-efficient of friction, contact mechanics and system of forces. This often results in discrepancy between the wear prediction using existing models and measured...