A future challenge to wheel/rail interaction analysis and design: Predicting worn shapes and resulting damage modes

Wheel/rail interaction remains a systemic problem never to be disassociated with the behavior of the vehicle on the track. The contact patch is often also the interface between the disciplines of vehicle and track design and maintenance. Consequently, any attempt to solve wheel or rail contact problems should always be cognizant of the demands of the total system and the players involved. This keynote presentation reviews current developments in North America impacting contact mechanics. Particular emphasis is placed on current developments in vehicle and track condition measurement and the role of wayside detection in controlling the size and position of the contact patch as well as the forces acting across this patch. The paper closes with a suggested challenge for the future: as flange and gage corner wear are increasingly controlled and as track tolerances improve, the wear of wheel and rail becomes increasingly concentrated on the wheel tread and the rail crown. It is suggested that, as a consequence, wheelset conicity and wheel and rail contact stress changes during the service life of the wheel may become greater than those under high flange wear conditions resulting in reduced vehicle stability and increased wheel and rail fatigue problems during the service life of the wheelset. Consequently, the prediction of wear and material flow patterns on wheel and rail becomes increasingly important in determining system performance as a function of system design parameters such as track gage, wheelset tolerances, and profile shapes for given track topology.