Author(s)

L. Zhang, S. Mellings, J. Baynham & R. Adey

Abstract

The two main causes of railway replacement are wear and rolling contact fatigue. Rolling contact fatigue has been a critical problem on UK railways. This paper describes recent developments in the modelling of cracks in rails, which incorporates in the model the contact between the crack faces during calculation of the Stress Intensity Factors (SIFs). This data is then combined with the SIFs caused by contact loading to provide a more realistic simulation of the crack growth. The way the methodology can be applied is described, for example using point loads to represent non-conforming contact to obtain the interaction between the wheel and the rail. The process of the wheel rolling over the crack can be modelled by moving the so called ‘contact patch’ along the rail. Various conditions can be applied to the crack, including frictionless contact between opposing surfaces, or frictional contact. In addition, pressure can be applied to the crack surfaces to take into account the water trapped inside the crack as the wheel rolls over. An example is given at the end of the paper to illustrate the advantages of the improved model. Keywords: rails, rolling contact fatigue, contact, crack growth, boundary element method (BEM). 1 Introduction The rolling contact fatigue has been a major issue for the British rail industry after the fatal derailment at Hatfield in 2000. On inspections across the national railway system, it was discovered that the rolling contact fatigue was more widespread and serious than previously thought. As a result, the track maintenance practices were modified, urgent rail replacement was undertaken and speed restrictions were imposed [1, 2].

Keywords

rails, rolling contact fatigue, contact, crack growth, boundary element method (BEM)