Creep forces in simulations of traction vehicles running on adhesion limit

doi:10.1016/j.wear.2004.03.046

Wear

Volume 258, Issues 7–8, March 2005, Pages 992-1000

https://doi.org/10.1016/j.wear.2004.03.046 Get rights and content

Abstract

A necessary condition for complex simulations of vehicle system dynamics including drive dynamics and traction control when running on adhesion limit, is an advanced creep force modelling taking large longitudinal creep into account. A method presented in the article allows to simulate various real wheel–rail contact conditions using one parameter set. The parameters can be identified from measurements or the recommended parameters for modelling of typical wheel–rail contact conditions in engineering applications can be used. Influence of vehicle speed, longitudinal, lateral and spin creep and shape of the contact ellipse is also considered. The method was validated by comparisons with measurements as presented in application examples.

Introduction

High adhesion utilisation and sophisticated vehicle dynamics design of modern locomotives and traction vehicles demands complex simulations which simultaneously take into consideration the mechanical, electrotechnical and control system fields.

In computer simulations, different methods are used to calculate tangential creep forces between wheel and rail:

•
for general vehicle dynamic calculations, without or with small tractive forces;
•
for analysis of traction chain dynamics and traction control with high tractive forces.

In vehicle dynamics, small creep values (microslip) are of main importance. Longitudinal and lateral creep as well as spin should be taken into account. The friction coefficient is assumed to be constant. The difference between dry and wet conditions is usually expressed only with the value of the friction coefficient.

In traction chain dynamics usually only the longitudinal direction is taken into account. There is a maximum of creep force–creep function, the so-called adhesion optimum, and a decreasing section behind this maximum. Typical shapes of measured creep force–creep functions for large creep are shown in Fig. 1. The form and the initial slope for wet, dry or polluted conditions are different.

For a complex simulation of dynamic behaviour of locomotive or traction vehicle in connection with drive dynamics and traction control, the different creep force models described above have to be made into one model. A suitable method is described in this article and its application illustrated in examples.

Section snippets

Overview

A possible explanation of the decreasing section of creep force–creep function for large longitudinal creep is the decrease of friction coefficient with increasing slip velocity due to increasing temperature in the contact area [1], [2], [3], [4], [5]. Another explanation – different friction coefficients in the area of adhesion and area of slip (static and kinematic friction coefficient) – does not seem to sufficiently influence the shape of the creep force curve [6], [7].

The assumption of

Influence of tractive force on the steering of a self-steering bogie

In order to test the possibility of simulating the dynamic change of traction torque, a test case used during the adhesion test [22] of the four axle SBB 460 locomotive of the Swiss Federal Railways was simulated. The locomotive design combines very good curving performance with high maximum speed due to the coupling of wheelsets, realised by a mechanism with a torsional shaft assembled to the bogie frame. The locomotive model in simulation tool ADAMS/Rail consists of 51 rigid bodies and

Conclusion

The proposed method for calculation of wheel–rail forces enables computer simulations of complex vehicle system dynamics including running and traction dynamics for large traction creep when running on adhesion limit. It allows to simulate various wheel–rail contact conditions using one parameter set for various speeds. Influence of longitudinal, lateral and spin creep and shape of the contact ellipse is also considered.

Measurements with five locomotives under different weather and wheel–rail

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Creep forces in simulations of traction vehicles running on adhesion limit

Abstract

Introduction

Section snippets

Overview

Influence of tractive force on the steering of a self-steering bogie

Conclusion

Einfluss der Kontakttemperatur auf den Kraftschlussbeiwert

Tribologie und Schmierungstechnik

Geschwindigkeitsabhängiger Kraftschluss hochbelasteter Rad-Schiene-Kontakte

Elektrische Bahnen

Thermal effect on adhesion in wheel/rail interface

Improved creep force model for wheel/rail contact considering roughness and temperature

Vehicle Syst. Dyn. Suppl.

Some basic studies on the influence of surface contamination on adhesion force between wheel and rail at higher speeds

Q. Rep. Railway Tech. Res. Inst.

Tangential contact problem with friction coefficients depending on sliding velocity

Solution of wheel–rail contact forces suitable for calculation of rail vehicle dynamics

A fast wheel–rail forces calculation computer code

Vehicle Syst. Dyn. Suppl.

A fast algorithm for the simplified theory of rolling contact

Vehicle Syst. Dyn.

A comparison of alternative creep force models for rail vehicle dynamic analysis

Kraftschluss bei Triebfahrzeugen – Modellbildung und Verifikation an Messdaten

Elektrische Bahnen

Rad-Schiene-Modelle in der Simulation der Fahrzeug- und Antriebsdynamik

Elektrische Bahnen