Abstract
The wear prediction 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 strategies for the design of optimal wheel and rail profiles from the wear point of view. The authors in this work present a model specifically developed for the evaluation of the wheel and rail wear and of the wheel and rail profiles evolution. The model layout is made up of two mutually interactive parts: a vehicle model for the dynamical analysis and a model for the wear estimation. The first one is a 3D multibody model of a railway vehicle where the wheel-rail interaction is implemented in a C/C++ user routine. Particularly, the research of the contact points between wheel and rail is based on an innovative algorithm developed by authors in previous works, while normal and tangential forces in the contact patches are calculated according to the Hertz and Kalker’s global theory, respectively. The wear model is mainly based on experimental relationships found in literature between the removed material by wear and the energy dissipated by friction at the contact. It starts from the outputs of the dynamical simulations (position of contact points, contact forces, and global creepages) and calculates the pressures inside the contact patches through a local contact model; then, the material removed by wear is evaluated and the worn profiles of wheel and rail are obtained. In order to reproduce the wear evolution, the overall mileage traveled by the vehicle is divided into discrete steps, within which the wheel and rail profiles are constant; after carrying out the dynamical simulations relative to one step, the profiles are updated by means of the wear model. Therefore, the two models work alternately until completing the whole mileage. Moreover, the different time scales characterizing the wheel and rail wear evolutions 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 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.
