Keywords: conformal contact model, wear, non-Hetzian contact, wheel profile, multibody simulation, wheel-rail contact, railway vehicle.

One of the main problems in railway and tramway systems, both dynamically (safety, comfort) and economically (planning of maintenance interventions, reduction of wheel and rail lifetime etc.), is represented by the wear of wheel and rail profiles, due to the wheel-rail interaction. The profile’s shape variation, caused by wear and material removing, influence the dynamic behaviour of the vehicle and, in particular, the wheel-rail contact conditions. Hence, nowadays, one of the most important topics in the railway field is the development of a reliable and efficient wear model to predict the wheel and rail profiles evolution. For this reason, the aim of this work is the development of a new efficient wear model for the evaluation of the wheel and rail profile evolution based on an innovative wheel-rail conformal contact model. More in detail, conformal contact conditions are really frequent in railway applications, particularly in sharp curves and, generally, in presence of worn profiles. Because all this reason, if an accurate wear assessment is required, this aspect cannot be neglected. In the proposed wear model, two separate blocks mutually interact: a multibody vehicle model for the dynamical analysis and a MATLAB/Simulink model for the wear evaluation. In the first one a multibody model of the vehicle, development in Simpack Rail, and an innovative and efficient conformal contact model based on an improvement of the Piotrowski classic contact model interact online during the dynamic simulations. Starting from the outputs of the dynamic simulations (position and shape of the contact patches, contact pressures, etc.), the wear model calculates the specific volume of removed material by wear through suitable experimental laws that correlate this volume to the friction power produced by the tangential contact pressures. Finally, the new updated profiles of wheel and rail are obtained by subtracting the material removed from the old ones.

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