Disc machine testing to assess the life of surface-damaged railway track

Abstract

Wheel-rail contacts operate in an arduous and contaminated environment. Railway track running surfaces can become damaged either prior to or during operation. This work is aimed at understanding how that surface damage can affect the life of railway track. Pre-damaged surfaces and track damaged by the entrainment of solid contaminants are considered under both oil and water lubrication. A series of small-scale laboratory experiments has been carried out on a twin-disc rolling-sliding test machine. The test discs are artificially indented and run under typical wheel-rail contact conditions. The experimental results revealed that artificial dents only reduce the fatigue life of the contact under oil, but not water lubrication. With oil lubrication the fatigue failure initiates close to the location of the surface defect. However, with water as the lubricant the whole of the surface undergoes cracking with the defect having no preferential effect. Studies have also been carried out to investigate the damage caused by the entrainment of solid particles into the wheel-rail contact. This kind of damage can accelerate surface fatigue and also lead to excessive wear. An attempt has been made to quantify the wear process and develop a simple empirical model.