The development of combination mechanical contact and thermal braking loads for railway wheel fatigue analysis

Abstract

The ability to predict crack growth in wheels has significant implications for existing rolling stock. Safety and the cost of wheel management practices will be improved through a scientific based tool for the review of current defect tolerance limits. This paper presents the results of a study into methods for estimating the residual lifetime of the rail S-shape plate rail wheel due to cyclic mechanical loads and thermal loads. The residual lifetime is the time or number of loading cycles which a crack needs for extending from the initial crack size (a0, c0), up to the allowable crack size (ac, cc). A simple synthetic method has been developed for accounting the effects from mechanical loads and thermal loads to damage tolerance analysis. The subsequent analysis is carried out for stress intensity factor of cracks in the rail wheel under service condition by using a semi-analytical solution technique that involves the use of an analytical solution combined with a numerical algorithm to assess fracture strength. An equivalent block method, based on the Generalised Frost–Dugdale approach, is used to modelling crack growth.