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With the aim of putting prediction and prevention of rolling contact fatigue of wheels and rails in context, the paper sets out with a description of the phenomena. This is followed by a discussion on predictive models with emphasis on influencing factors needed to be accounted for and how these can be incorporated in a predictive model of surface and subsurface initiated rolling contact fatigue (RCF)...
Optimised maintenance of railway tracks requires knowledge of how a deteriorated track geometry will affect subsequent damage of the track. In this study the influence on rolling contact fatigue (RCF) is investigated through numerical simulations featuring a freight wagon run on tracks with a single track irregularity or with a track irregularity spectrum generated from a power spectral density. Evaluated...
Braking events in railway traffic often induce high frictional heating and thermoelastic instability (TEI) at the interfacing surfaces. In the present paper, two approaches are adopted to analyse the thermomechanical interaction in a pin-on-disc experimental study of railway braking materials. In a first part, the thermal problem is studied to find the heat partitioning between pin and disc motivated...
Wear of brake blocks at tread braking of railway wheels is one of the key factors that control the time period between scheduled train maintenance and hence has a substantial impact on the life cycle cost of the vehicle. Wear simulations using two different numerical models, one thermal model and one thermoelastic model, are presented implementing wear rates for some brake block materials exploiting...
This paper addresses the problem of asymmetric flange wear of a particular type of 3-axle (2C 0 -type) locomotive that runs on the Chinese railway system. In particular, the influence on wheelset asymmetric wear of errors in the longitudinal location of the journal box is examined. Based on a 2C 0 -type locomotive dynamics model, the influence of the journal positioning deviation at...
When adding substances to the wheel–rail contact, they mix with wear particles and form a Third Body Layer (3BL). This layer influences the initial gradient of the traction characteristic.During twin-disc tests presented in this paper, a granular layer consisting of iron and iron oxides with a thickness of up to 50μm was found. In addition, a creepforce model is presented that uses non-linear properties...
Lubrication between wheel and rail in curves is generally known to decrease the friction between wheel and rail, resulting in the reduction of wear of wheel flange and rail gauge corner in high rail, corrugation growth in low rail and noise generation at both of high and low rails. However, the selection of kinds of lubricants and their application methods adopted by railway companies are not necessarily...
This article presents empirical findings relating to both head check growth and wear development and discusses a number of studies that have examined key factors influencing head check development. Advanced analysis of head check growth is necessary in order to determine the optimum time for preventive rail grinding and to enable crack propagation rates to be taken into account when planning and carrying...
Corrugation growth has perplexed many researchers for several decades with remaining challenges including its reliable prediction in the field. In the present paper, the effect of environmental variations on corrugation growth is investigated using field measurements and mechanics-based modelling. Statistically significant relationships between average daily rainfall, humidity and the growth of rail...
Problems in tribology and contact mechanics are becoming increasingly amenable to solution through models and simulation. But in application to the wheel/rail contact, there remain a number of very important features for which either gross simplifications or a lack of understanding or ability severely limits the success of those efforts. Examples include models of friction and material response (including...
Railway vehicles require a certain level of wheel–rail adhesion for efficient, reliable, and economical operation. A comprehensive wheel–rail contact model is useful for optimizing the adhesion, to simulate vehicle running conditions and to predict wear and rolling contact fatigue. A new contact model using measured 3D surfaces has been developed, comprising normal contact, rolling–sliding contact,...
The demand to investigate and predict the surface deterioration phenomena in the wheel–rail interface necessitates fast and accurate contact modelling. During the past 20 years, there have been attempts to determine more realistic contact patch and stress distributions using fast simplified methods. The main aim of the present work is to compare some of these state-of-the-art, non-elliptic contact...
One of the main sources of damage in railway components is the large plastic deformations that accumulate in the surface layer under rolling contact loading. Large irreversible deformations in components made of pearlitic steel induce anisotropy in mechanical properties of the material in the surface layer. In the present work the influence of the anisotropic layer on propagation of cracks in rail...
Wear phenomena like flange wear and hollow-worn tread of HXN5 locomotive wheels are studied by a nonlinear iterative procedure. For better understanding of these specific wheel wear mechanism, a numerical solution is developed by a combination of a SIMPACK multibody model and Archard's wear theory. The wheel wears can be predicted by the nonlinear wear formulation, in which real time parameters of...
A preliminary two dimensional numerical model of wheel/rail in rolling contact is established to study the adhesion characteristics of wheel/rail with considering surface roughness under oil and water mixed contamination. A partial elastohydrodynamic lubrication (EHL) theory in line contact is applied in the model. The present numerical model is used to investigate the effects of contact pressures...
Tests have been carried out to assess the performance of ten different grease types used as curve lubricants. All greases tested have been designed for wayside flange lubrication and some are currently used on the UK’s rail network. Each grease's performance was assessed in terms traction coefficient, retentivity (how long a fixed amount of grease provided lubrication), and wear. Two series of tests...
Boundary element modelling was conducted to investigate rail cracks subject to combined thermal and contact loading such as occurs in ‘stud’ or ‘squat type’ defects in which white etching layer lies above shallow cracks formed without evidence of plastic flow. An embedded crack at 0.5mm below the rail surface was modelled, revealing a thermal mechanism of crack opening. Stress intensity values for...
The paper studies the influence of rail weld dip on wheel–rail contact dynamics, with particular reference to freight trains where it is important to increase the operating speed and also the load transported. This has produced a very precise model, albeit simple and cost-effective, which has enabled train–track dynamic interactions over rail welds to be studied to make it possible to quantify the...
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