Sharp curved track corrugation: From corrugation observed on-site, to corrugation reproduced on simulators
Résumé
For more than a century, rail corrugation has been a major issue for mass transit networks. Although studied mainly by global analyses of train/track dynamics, knowledge about why corrugation appears on some types of trackform in some circumstances and not in others remains inadequate. One explanation is that these studies mainly overlooked the question of local wheel-rail interactions due to the difficulty to obtain contact data by in situ instrumentation and also to model them reliably. To provide more insight into rail corrugation modelling, this paper gives more tribological details on the onset of corrugation: * * Firstly, characteristics of corrugation are highlighted from both points of views: local, through a posteriori observations, and global, through on-site measurements. Corrugation troughs are characterized by a detachment of particles and a lateral sliding. Such characteristics may nevertheless be the cause or consequence of the periodical geometry of corrugation pre-existing on the rail surface. * * The veil on such dilemma is then lifted by laboratory testing at both full-scale, under imposed global train-track conditions, and reduced-scale, under imposed local contact conditions. Lateral slip variation in the wheel-rail contact is clearly the dominant cause of the periodical detachment of particles that digs corrugation troughs.