A study of the falling friction effect on contact parameters through exact contact models

Giner, J., Vila, P., Alonso, A. and Baeza, L. (2014) A study of the falling friction effect on contact parameters through exact contact models. Pombo, J. (ed.) In Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance. vol. 104, Civil-Comp Press.. (doi:10.4203/ccp.104.190).

Abstract

The dependence of the coefficient of friction on the local slip velocity has been associated in the literature with many important railway problems such as the squeal noise that occurs in narrow curves, certain types of corrugation of rails, braking, etc. In order to consider this effect, some researchers have tried to develop models usually based on simplified theories from Kalker that would not be adequate for considering the falling friction coefficient. In this paper a methodology based on Kalker's variational theory is presented, in which a local slip velocity-dependent friction law is considered. A formulation is proposed to first obtain, steady-state conditions of contact through an exact elastic model and second, macro-properties (creepage velocities versus total longitudinal forces) through local-properties (local slip velocity versus coefficient of friction) and vice versa. Additionally, the unsteady variational theory by Kalker is modified by introducing a regularisation of the Coulomb's law. Numerical and computational improvements and non-stationary convergence strategies are discussed.

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Contributors

Author: L. Baeza

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