MODELLING THE EFFECT OF TRACK STIFFNESS VARIATION ON WHEEL RAIL INTERACTION USING FINITE ELEMENT METHOD (original) (raw)
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Experimental and numerical modelling of wheel–rail contact and wear
Wear
In the field of simulation of railroad vehicles, there are many numerical models to estimate the interaction forces between the wheel and rail. The main advantage of these models is that they can be used together with multi-body dynamics software to calculate the motion of a vehicle in real time. However, the result of these contact models is usually post-processed to estimate wear on the profiles and some hypotheses assumed by the contact models may be inadequate for wear analysis. This is the case when considering surface roughness, which is not introduced in the numerical models and makes wear prediction imprecise. In this work an experimental method based on the measurement of ultrasonic reflection is used to solve the contact problem, together with a FASTSIM (simplified theory of rolling contact) algorithm. This technique is suitable to deal with rough surfaces and gives a better approximation of the material behaviour. Wear is estimated by means of the energy dissipation approach (T•gamma). Two different contacts are investigated, using wheel and rail profiles coming from unused and worn specimens. In order to obtain realistic results, special care is taken when locating the specimens to reproduce the same contact that appears between the wheel and the rail in the track.
Wear, 2004
This paper declares the method for the computation of the wheel-rail surface degradation in a curve where the major surface degradation phenomenon is a combination of wear and plastic deformation. Simulating the form change of the wheel-rail contacts help to identify the risk of severe or catastrophic wear resulting from increased train speeds and axle loads and can help in determining more efficient maintenance schedules for track and rolling stock. The method was previously used to simulate the form change in a two-roller contact. The progress is made in the terms of general geometry modelling, which makes differences in the various contact configurations. The normal contact problem is analysed using the modified Winkler method and calibrated using the results from FEM modelling of the wheel-rail contact with elastic-plastic material model. A piecewise approach and stick-slip analysis of the rolling-sliding contact solves the tangential problem. A linear wear law is used in the wear computation. The form change for a typical two-point contact in a low radius curve was analysed and discussed.
Computers & Structures, 2011
Nowadays, one of the most sensible issues in the railway industry is the damage on vehicles caused by the track conditions and the infrastructure deterioration due to the trains' passage. Therefore, it is essential to acquire a better understanding on how the operation conditions influence the wear evolution of the railway wheels and the consequences of their changing profiles on vehicle-track interaction forces. In this work, a computational tool is used to simulate the dynamic performance of integrated railway systems and to predict the wear evolution of wheel profiles. The tool is applied to realistic operational scenarios with the purpose to evaluate the influence of the track conditions, defined by the track geometry and by its irregularities, on the wear progression of railway wheels. The loads imposed to the railway infrastructure by a trainset running at different velocities, on a track with and without irregularities, and equipped with wheelsets having new and worn profiles is also studied. The studies performed here show that the levels of track irregularities considered have a negligible influence on the wear progression. Furthermore, the loads imposed to the track during trainset operation are not affected by the wear state of the wheels. On the other hand, the track imperfections can affect significantly the vehicle-track interaction forces.
An Investigation Into Effect of Train Curving on Wear and Contact Stresses of Wheel and Rail
Volume 2: Automotive Systems; Bioengineering and Biomedical Technology; Computational Mechanics; Controls; Dynamical Systems, 2008
Some important papers concerning the studies on rail wear and wheel/rail contact stresses are briefly reviewed. The present paper utilizes a numerical method to analyze the effect of railway vehicle curving on the wear and contact stresses of wheel/rail. The numerical method considers a combination of Kalker's non-Hertzian rolling contact theory, a material wear model and a vertical and lateral coupling dynamics model of the vehicle/track. In the analysis, the important factors influencing on the wear and the contact stresses are, respectively, the curving speed, the curved track super-elevation and the rail cant. Compared to the present model, some concerned models and results in the published papers are in detail discussed. Through the detailed numerical analysis, it is found that the difference between the normal loads of the left and right of the wheelset increases linearly with increasing the vehicle curving speed. The material wear volume per length along the rail running surface has a tendency to grow. However, the variation of the maximum normal contact stress has a large fluctuation as the curving speed increases. The increase of the maximum contact stress depends greatly on not only the normal load but also the profiles of the wheel/rail. Increasing the track super elevation efficiently lowers the normal load difference of the left and right of the front wheelset, and the contact stresses and the wear. The rail cant has a great influence on the low rail wear of the curve track. An increase in rail cant results in a great increase in the low rail wear of the curved track, and a decrease in the outside rail wear. These conclusions are very useful in the maintenance of the track.
An investigation into the effect of train curving on wear and contact stresses of wheel and rail
Tribology International, 2009
Some important papers concerning the studies on rail wear and wheel/rail contact stresses are briefly reviewed. The present paper utilizes a numerical method to analyze the effect of railway vehicle curving on the wear and contact stresses of wheel/rail. The numerical method considers a combination of Kalker's non-Hertzian rolling contact theory, a material wear model and a vertical and lateral
Computer-aided simulation of the wheel-rail interaction was performed with the help of the program code "Universal Mechanism» and its version "UMWear", the tribodynamic model, enabling to find wheel or rail profile evolution due to wear. Specific features of wheel and the rail profiles' evolution model are described. The objectives of simulation are to find the influence of various track and vehicles parameters on wheel/rail interaction characteristics, such as wheel/rail friction work and wheel wear, contact parameters, temperature and safety factor characterizing derailment risk. Some conclusions on a degree of the influence are made.
Prediction of wheel and rail profile wear on complex railway networks
International Journal of Rail Transportation, 2014
The modelling and the reduction of wear due to wheel-rail contact represents a crucial issue in railway applications, mainly correlated to safety, maintenance interventions and definition of strategies aimed at wheel profile optimization. A model for evaluating wheel and rail profile evolution due to wear developed for complex railway networks is presented in this paper. The model layout is composed of two mutually interacting but separate parts: a vehicle model (composed of multibody model and global contact model) for the dynamical simulations and a unit for wear computation (composed of the local contact model, the wear evaluation procedure and the profile update strategy). In order to achieve general significant accuracy results in reasonable computational effort, a suitable statistical approach for the railway track description is used, aimed at studying complex railway lines: in fact, the exhaustive analysis of vehicle dynamics and wear evolution on all the railway network is too expensive in terms of computational time for each practical purpose. The wear model has been validated in collaboration with Trenitalia S.P.A and RFI, which have provided technical documentation and experimental data relative to some tests performed on a environment exhibiting serious problems in terms of wear: the vehicle ALn 501 Minuetto operated on the Aosta-Pre Saint Didier Italian line.
Integrating dynamics and wear modelling to predict railway wheel profile evolution
2003
The aim of the work described was to predict wheel profile evolution by integrating multi-body dynamics simulations of a wheelset with a wear model. The wear modelling approach is based on a wear index commonly used in rail wear predictions. This assumes wear is proportional to Tγ, where T is tractive force and γ is slip at the wheel/rail interface. Twin disc testing of rail and wheel materials was carried out to generate wear coefficients for use in the model. The modelling code is interfaced with ADAMS/Rail, which produces multi-body dynamics simulations of a railway wheelset and contact conditions at the wheel/rail interface. Simplified theory of rolling contact is used to discretise the contact patches produced by ADAMS/Rail and calculate traction and slip within each. The wear model combines the simplified theory of rolling contact, ADAMS/Rail output and the wear coefficients to predict the wear and hence the change of wheel profile for given track layouts.
2013
In railway applications, the wear estimation at the wheel-rail contact is an important field of study, mainly correlated to the planning of maintenance interventions, vehicle stability and the possibility to carry out specific strategies for the wheel profile optimization. In this work the Authors present a model for the evaluation of the wheel and rail profile evolution due to wear specially developed for complex railway networks. The model layout is made up of two mutually interactive but separate units: a vehicle model for the dynamical analysis and a model for the wear evaluation.To study complex railway lines the Authors also proposed a new statistical approach for the railway track description in order to achieve general significant accuracy results in a reasonable time. The wear model has been validated in collaboration with Trenitalia S.P.A and Rete Ferroviaria Italiana (RFI), which have provided the technical documentation and the experimental data relating to some tests performed on a scenery that exhibits serious problems in terms of wear: the vehicle DMU ALn 501 Minuetto circulating on the Aosta-Pre Saint Didier Italian line.