RESEARCH ARTICLE


Modelling of Friction Coefficient for Shoes Type LL By Means of Polynomial Fitting



L. Cantone1, *, A. Ottati2
1 Department of Engineering for Enterprise “Mario Lucertini" - University of Rome “Tor Vergata”, via del Politecnico, 1, 00133 Rome, Italy
2 Tecnologie Meccaniche e Sistemi Frenanti - Ingegneria Rotabili e Tecnologie di Base, Direzione Tecnica TRENITALIA, Viale Spartaco Lavagnini, 58, 50129, Firenze, Italy


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Creative Commons License
© 2018 Cantone and Ottati.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Engineering for Enterprise “Mario Lucertini" - University of Rome “Tor Vergata”, via del Politecnico, 1, 00133 Rome-Italy, Tel: +390672597133; E-mail: Luciano.Cantone@uniroma2.it


Abstract

Introduction:

The paper describes the automatic procedure, implemented in UIC software TrainDy, for the simulation of friction coefficient of new LL shoes, used to avoid noise from freight traffic.

Method:

This procedure uses certified experimental data obtained at dynamometer bench as input data and computes a series of polynomials laws that describe the evolution of friction coefficient with speed, for different values of normal force between brake blocks and wheel and for different initial braking speeds.

Result:

Numerical results are compared against two series of experimental slip tests, carried on Trenitalia freight wagons, in terms of both stopping distances (for different starting speeds and loading conditions) and pressure in brake cylinder, speed and acceleration. Errors in terms of stopping distance are always below 5% whereas errors in terms of maximum acceleration are up to 20%.

Keywords: Freight trains, Type LL, Composite shoes, Friction coefficient, Train noise, Longitudinal Train Dynamics (LTD), TrainDy.