Trith-Saint-Léger, France
Trith-Saint-Léger, France

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Baudoin P.,University of Lille Nord de France | Baudoin P.,Lille Laboratory of Mechanics | Magnier V.,University of Lille Nord de France | Magnier V.,Lille Laboratory of Mechanics | And 9 more authors.
MATEC Web of Conferences | Year: 2013

This study aims at characterizing the influence of gradients at different scales (loading, geometry, microstructure⋯) on fatigue strength through a multi-scale finite element modeling associated to several high cycle fatigue criteria. This is a necessary step in the perspective of conducting a relevant experimental campaign on notched specimen exhibiting a gradient of mechanical properties. © Owned by the authors, published by EDP Sciences, 2013.


Langueh A.,University of Lille Nord de France | Langueh A.,Lille Laboratory of Mechanics | Brunel J.-F.,University of Lille Nord de France | Brunel J.-F.,Lille Laboratory of Mechanics | And 6 more authors.
Procedia Engineering | Year: 2011

The aim of this work is to develop a numerical approach which is able to include the inelastic material behavior in order to compare the different steel grades influence on rolling contact fatigue of railways wheels according to practical conditions. The main stages are the identification of the material behavior using genetic algorithms, the determination of the stress-strain fields by steady-state method and the application of a fatigue criterion. Two steels usually used for the manufacturing of wheels have been studied: R7T and R9T. Their influence has been numerically studied. Results show that the local stress-strain path along the streamline and the fatigue stress path differ depending on the steel grades and consequently the risk of damage can be affected, allowing a classification of the material grades face the risk on rolling contact fatigue. © 2011 Published by Elsevier Ltd.


Langueh A.M.G.,University of Lille Nord de France | Langueh A.M.G.,Lille Laboratory of Mechanics | Brunel J.-F.,University of Lille Nord de France | Brunel J.-F.,Lille Laboratory of Mechanics | And 8 more authors.
Fatigue and Fracture of Engineering Materials and Structures | Year: 2013

This paper proposes a numerical approach based on a steady-state algorithm to predict the rolling contact fatigue crack initiation in railway wheels in practical conditions. This work suggests taking into account the cyclic hardening of the wheel's material and one of its originality is to conduct a complete numerical approach whatever the loading level. The main stages are the characterization and modelling of the material behaviour, the determination of the stress-strain fields using a numerical steady-state method and the application of a high cycle fatigue criterion. Computations were made with the Abaqus FE commercial software. Three cases are studied: rolling with or without sliding and skating. The numerical results give several types of mechanical responses: elastic or plastic shakedown. Otherwise, the results show that the location where the shear stress is maximal is not the same as where the risk of crack is the highest. © 2013 Wiley Publishing Ltd.


Brunel F.,University of Lille Nord de France | Brunel J.-F.,University of Lille Nord de France | Dufrenoy P.,University of Lille Nord de France | Demilly F.,GHH Valdunes
Journal of Thermal Stresses | Year: 2013

This article presents a prediction of the residual stresses that are introduced by the heat treatment in the manufacture of railway wheels. It is well known that this treatment induces the formation of a layer of residual circumferential (hoop) compressive stresses on the tread surface. This stress field may be reversed during service loading, especially tread braking. Tensile stresses at the wheel tread that arise from repeated braking may lead to the initiation of surface cracks. The work presented here defines a methodology for determining the as-manufactured residual stress field prior to service loading. A thermal and mechanical finite element model was used to study the residual stress evolution during the heat treatment. The heat transfer coefficient during quenching was determined by means of a dedicated experimental setup. The results show that the numerically computed residual stresses correlate strongly with the experimental residual stresses determined by ultrasound when the model material includes time-dependent effects such as creep or viscoplasticity. © 2013 Taylor & Francis Group, LLC.


Marshall M.B.,University of Sheffield | Lewis R.,University of Sheffield | Dwyer-Joyce R.S.,University of Sheffield | Demilly F.,GHH VALDUNES | Flament Y.,GHH VALDUNES
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | Year: 2011

Railway wheels are secured onto the axle by means of an interference fit. The wheel is either shrink fitted or press fitted onto a pre-lubricated axle, and the resulting interference fit induces a contact pressure at the interface. Occasionally railway axles fail by fatigue, with the initiation point for the failure frequently traced to the interference fit. In this study, the reflection of ultrasound was used to determine contact conditions in the interference fit. It is a non-intrusive technique preserving the mechanics of the contact. The concept is simple; an acoustic wave bounces back from an incomplete interface. The higher the contact load, the more conformal the contact and hence more of the wave will be transmitted. A spring model is used to determine maps of contact stiffness from ultrasonic reflection data. A calibration procedure is then used to determine the pressure. Two types of wheelsets were used for the measurements, both with a hollowaxle that was used as an access point for the ultrasonic transducer. The wheels differed in the design of their web sections. Variations were detected in the determined interface pressure profiles, due to both surface roughness effects and discontinuities in the fit geometry. When comparing the two fits, it was found that material removal from the web of the wheel in the second fit reduced the interface pressure distribution. © SAGE Publications Ltd 2011.

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