Implementation of the rheological dry friction model in fastsim algorithm for locomotive traction studies

The well-known Polach theory frequently used for modeling creep forces in locomotive traction studies is based on the friction coefficient dependent on slip velocity equation that was delivered with the usage of numerical experimental techniques, and it does not actually represent the background built on the physical theory developed by Kragelsky in 1948 for the description of a dry friction process at the wheel-rail contact zone. In this paper, the explanation is presented of the physical background of the friction equation and how it has been transformed to the friction modelling approach for the original Fastsim algorithm, and how it has been validated with the wheel-rail tribomachine experiment performed under dry friction conditions. The developed approach is implemented in multibody software code and creep force comparison simulations have been performed for a locomotive running under traction conditions with the developed and modified Fastsim approaches. The obtained results are presented, and limitations for the application of the developed approach are discussed.