posted on 2024-07-09, 21:42authored byS. Ranjha, Kan Ding, P. Mutton, Ajay KapoorAjay Kapoor
The probability of catastrophic rail failure as a result of the propagation of surface-initiated rolling contact fatigue (RCF) cracks to form transverse defects (TDs) is of ongoing concern to the rail industry, especially since the Hatfield incident in the UK in 2000. The heavy haul sector is not immune to such concerns, as the combination of improved rail steels and optimisation of the wheel-rail interface has reduced the extent to which rail wear influences rail life. The purpose of this paper is to investigate the growth behaviour of gauge corner cracking (GCC), and in particular, the tendency for rails to break with a rapid fracture, under the high axle load conditions typical of those that exist in Australian heavy haul operations. Previous work has shown that the occurrence of tension spikes as a result of localised vertical and lateral head bending on the web were significant in the understanding of this behaviour, which is exacerbated with increasing rail head wear (HW), such that the occurrence of the rapid fracture associated with this behaviour correlates with the extent of rail HW. This behaviour was examined using finite element (FE) modelling, which had previously been validated by comparison with in-track measurements to verify the prediction of the tension spikes. The FE model used a single rail on a discrete elastic foundation to parametrically study the growth behaviour of RCF damage subjected to changes in the rail HW; the contact patch offset (CPO) from the rail centreline, the (UV) ratio of lateral (L) to vertical (V) loads, foundation stiffness and the thermal stresses. The FE results reveal that existing GCC, when subjected to high tensile stresses at the underhead radius (UHR) and the gauge corner region, can contribute to the development of rapid (unstable) fracture. The results of this work can be used to examine the influence of wheel-rail interaction behaviour and rail HW on the probability of catastrophic rail failure from RCF damage.