Development of a wear model for the prediction of wheel and rail profile evolution in railway systems

Abstract

a b s t r a c tThe prediction of the wear at the wheel-rail interface is a fundamental problem in the railway field, mainly correlated to the planning of maintenance interventions, vehicle stability and the possibility of researching specific strategies for the wheel and rail profile optimization. In this work the Authors present a model specifically developed for the evaluation of the wheel and rail profile evolution due to wear, whose layout is made up of two mutually interactive but separate units: a vehicle model for the dynamic analysis and a model for the wear estimation. The first one is made up of two parts that interact online during the dynamic simulations: a 3D multibody model of the railway vehicle implemented in Simpack Rail (a commercial software for the analysis of multibody systems) and an innovative 3D global contact model (developed by the Authors in previous works) for the detection of the contact points between wheel and rail and for the calculation of the forces in the contact patches (implemented in C/C++environment). The wear model, implemented in the Matlab environment, is mainly based on experimental relationships found in literature between the removed material and the energy dissipated by friction at the contact. It starts from the outputs of the dynamic simulations (position of contact points, contact forces and global creepages) and calculates the pressures inside the contact patches through a local contact model (FASTSIM algorithm); then the material removed due to wear is evaluated and the worn profiles of wheel and rail are obtained. This approach allows the evaluation of both the quantity of removed material and its distribution along the wheel and rail profiles in order to analyze the development of the profiles shape during their lifetime.The whole model is based on a discrete process: each discrete step consists in one dynamic simulation and one profile update by means of the wear model while, within the discrete step, the profiles are supposed to be constant. The choice of an appropriate step is fundamental in terms of precision and computational load. Moreover the different time scales characterizing the wheel and rail wear evolution require the development of a suitable strategy for the profile update: the strategy proposed by the Authors is based both on the total distance traveled by the considered vehicle and on the total tonnage burden on the track. The entire model has been developed and validated in collaboration with Trenitalia S.p.A. and Rete Ferroviaria Italiana (RFI), which have provided the technical documentation and the experimental results relating to some tests performed with the vehicle DMU Aln 501 Minuetto on the Aosta-Pre Saint Didier line.

Determination of rational roughnes of the side surface of the rail top in curved sections of the underground railway track

“…Basically, among the possible ways to achieve this, the change of the contact parameters was considered. In particular, it was noted that, despite the high cost of replacing worn-out wheels and rails, and the labor content of repair work, the solution of these problems is a priority [2][3][4]. For now, the problem of reducing the wear rate for the contact «wheel-rail» taking into account all features of contacting wasn't resolved.…”

An innovative degraded adhesion model for railway vehicles: development and experimental validation

“…More particularly, new theoretical and experimental relations among the adhesion coefficient f , the specific dissipated energy W sp and the limit adhesion levels f d , f r (degraded adhesion and adhesion recovery) will be introduced and analysed. This way the physical origin and meaning of the transition function λ(W sp ) will be better investigated, trying to connect it to more elementary physical and tribological phenomena (for example phenomena related to wear of the wheel and rail profiles on which the authors have recently worked; see for instance the references [9,25,53,54]). …”

Study on modeling and numerical analysis for the prediction of wheel wear development

“…It is generally known that the evolution of the profile shape of the wheel and rail due to wear strongly affects vehicle dynamics and running stability, leading to variations in performance in negotiating both curves and straight track, (Ignesti et al, 2012).…”