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In order to simulate the wheel wear behaviour of freight cars, the rail vehicle's multi-body dynamical model and wheel wear simulation programme were combined as a wheel wear simulation tool in this paper. Multi-body dynamical models of China's heavy haul freight cars such as the C80, C80H, C70 and C70H, were built in SIMPACK software and the track system was built based on the China's Ring-line....
Numerical simulation of the behavior of rail vehicles requires a frictional contact model for the wheel–rail contact forces that must be fast and detailed. A comment on Kalker's original theories is that they describe well only the situation for scrupulously clean surfaces. Measured creep versus creep force curves show two important deviations: a reduced initial slope of the traction curve, i.e. smaller...
To improve wear resistance of wheel steels under rolling–sliding wear conditions, a novel technique named laser dispersed treatment (LDT) was used by forming a regular scattered hardening pattern distributed on the surface of wheel disc, which can avoid soft zones induced by tempering effect or cracks in the overlapped region. The wear rate of LDT wheel disc was evaluated by twin-disc wear testing...
In order to investigate vertical dynamic wheel/rail interaction resulting from a polygonal wheel at high-speeds, a vertical vehicle-track coupled dynamics model is adopted. The measured results from German ICE polygonal wheels are utilized as multi-harmonic excitations. Two types of out-of-round wheels, the periodic and the non-periodic, are simulated and compared. The dynamic wheel/rail interaction...
In this paper the authors present a predictive model of train energy requirements due to the application of a top of rail friction modifier (TOR-FM) versus dry wheel/rail conditions. Using the VAMPIRE® Pro simulation package, train energy requirements are modeled for two sets of TOR-FM frictional conditions, one using full Kalker coefficients and the other by using a Kalker coefficient of 18%. Both...
Prediction of the evolution of rail (and wheel) profiles using design tools that integrate multi-body dynamics (MBD) simulations of track and rail vehicles with tribological models of material removal are well established and well documented. The most adopted approach within the UK utilises the relationship between material loss and energy at the contact using the Tγ parameter. This relies on establishing...
Most available wheel/rail interaction models for the prediction of impact forces caused by wheel flats use a Hertzian spring as contact model and do not account for the changes in contact stiffness due to the real three-dimensional wheel flat geometry. In the literature, only little information is available on how this common simplification influences the calculation results. The aim of this paper...
A model to predict the ratcheting behavior of the near-surface material layer under high traction coefficients has been developed. The model explicitly takes into account the longitudinal, lateral and spin creep in determining the displacement increment at the surface due to plastic shear deformation. The model is computationally efficient and allows to perform plasticity calculations based on results...
Coefficient of friction is a significant factor for investigating stress and strain on the contact surface for a problem on torsional fretting wear. First, in this paper, a variable coefficient of friction model related to space and time is introduced. The evolution of friction coefficient is governed by the local contact history and the slip distance. Then, this model is implemented in the finite...
Multi-body-system (MBS) simulation is widely used in the railway industry. One of its major topics is the assessment of rolling contact fatigue (RCF). This damaging process is linked to plasticity. MBS wheel–rail contact models usually neglect plasticity as it does not change the vehicle behaviour. With the proposed method, contact stresses are consistent with a perfect plastic law. This new method...
The authors researched and developed a new measurement method that can continuously measure the contact forces and derailment coefficients at all curves of commercial lines. This new method can determine the derailment coefficients, which change according to the friction coefficients and other factors, using the measuring system on in-service trains. In this paper, the analysis results for actual...
Low adhesion affects rail networks around the world. A recent unpublished study by Network Rail has shown a strong correlation between low adhesion incidents and the occurrence of the dew point. It is hypothesised that at or below the dew point water vapour from the air condenses onto the railhead forming a fluid film that leads to a loss of traction within the wheel/rail contact. It has been proposed...
The comparison of quasi-static and hydrodynamic modelling of liquid–solid interaction in 3D squat-type cracks is presented. The hydrodynamic interaction is modelled by coupling the 3D finite element model of a squat-type crack and the theoretical squeeze fluid film model of liquid contained in the crack interior. In the finite element model, the contact interaction between rail and wheel is simulated...
In this work finite element models at different length scales are applied to predict the performance of three different crossing materials (Manganese steel, Hardox and Marage 300) in view of the development of rolling contact fatigue (RCF) cracks. A model of the whole crossing (crossing model) is used for the calculation of the dynamic forces and movements of wheel and crossing. For the prediction...
This paper investigates the damage behaviour of several pearlitic rail steels with special focus on three specific damage mechanisms – wear, plastic flow and rolling contact fatigue (RCF, head checks in particular). Multiple tests were conducted on a full scale test-rig at voestalpine Schienen GmbH under dry contact conditions. The obtained results were compared with data from selected track tests...
The material response of a railway wheel subjected to thermomechanical rolling contact is evaluated. Thermal and mechanical loads are combined in a three-dimensional sequentially coupled analysis where nodal temperatures from a transient thermal analysis are applied as predefined fields in a structural analysis featuring an elastic–plastic material model. The mechanical contact load is prescribed...
Wear and rolling contact fatigue of rails are a major problem for the railway industry and it is of great importance to develop models for prediction of rail life. In this paper, a 2D FE model is used to simulate crack growth of a single head check-like RCF crack in an idealised rail. The presented model takes into account wear through crack truncation and allows for crack curving. The influence of...
The wheel/rail vertical loads are strongly affected by the aerodynamic loads and track excitations, and will further influence the wheel/rail adhesion forces. With the increasing of train speed, the influence of aerodynamic loads becomes more and more significant. In order to probe into this problem, a simplified train dynamic model with three vehicles is established in which each vehicle system has...
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...
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