Railway turnouts are important components of railway infrastructure as they provide flexibility and guidance to the rail traffic. Because of geometrical discontinuities in the crossing area of the turnouts, high impact forces due to passing wheels acting on the crossing nose can occur. In the field, severe rail damage problems are found in crossing areas. Statistical evidence shows that turnout failures cause major operational disturbances in a railway network, which lead to higher maintenance costs as compared with other track components. The research presented here was motivated by the short service life of the turnout crossing observed in the Dutch railway network and by the need to improve the performance of railway turnouts. Moreover, there is a lack of advanced numerical tools such as dynamic three-dimensional (3-D) models to analyse wheel–rail interactions in crossings on the stress and strain levels, particularly for models that are coupled with life estimation of the crossing. Therefore, the goal of this study is to develop numerical tools for the analysis of the dynamic interaction between the wheel and turnout crossing, and the prediction of fatigue life of crossings, aiming to improve the crossing performance and prolong its service life.@en

In this paper, the effects of repair welding and grinding, which are currently the main components used in the maintenance of crossings, on the performance of crossings are analyzed. It has been observed that sometimes the welding and grinding activities that directly affect the geometry of the crossings and/or material properties can have negative effects on the performance and ultimately on the service life of the crossings. In this paper, the effect of the changes of geometry has been studied experimentally, while the effect of the changes in the material properties has been analyzed using a numerical model. When grinding the shape of the crossing nose, the resulting profile can deviate from the original one. To analyze the geometry-related effects of welding and grinding, the geometry of crossings (cross-sectional profiles) as well as the corresponding dynamic accelerations due to passing trains are measured before and after the welding and grinding activities. Based on the comparison of the measured accelerations, the performance of the measured crossings has been assessed. Also, a welding repair that is not properly performed can lead to undesirable changes in the material properties of the rails, resulting in defects in rails. The material-related effects of the welding and grinding are studied using the three-dimensional explicit finite element model wherein a wheelset moves over a railway crossing. To understand the microstructure of the welding defect and provide an input for the numerical model, the results of ultrasonic and microscopic analyses of some welded crossings are presented first. Then, a number of the numerical simulations of the crossing with the welding defect are performed to investigate the failure mechanism of the crossing. Furthermore, assessment using the fatigue model (coupled with the finite element model) that accounts for the ratcheting behavior of material by calculating a number of the load cycles to the crack initiation is performed. Finally, conclusions on the effects of changes in geometry and material of the crossings due to repair welding and grinding are given. @en

In this paper a numerical procedure for analysis of rolling contact fatigue crack initiation and fatigue life prediction for the railway turnout crossing is presented. To analyse wheel–rail interaction, a three-dimensional explicit finite element (FE) model of a wheelset passing a turnout crossing is developed to obtain the dynamic responses such as the contact forces, displacements and accelerations as well as the stresses and strain in the crossing nose. The material model accounting for elastic–plastic isotropic and kinematic hardening effects in rails is adopted. The fatigue life of the rails is defined as the time to rolling contact fatigue crack initiation. In predicting the fatigue life Jiang and Sehitoglu model is used, which is based on the critical plane approach. Using the FE simulation results the ten critical locations on the crossing nose susceptible to crack initiation are determined first. Then, using the fatigue model the critical planes in these locations are obtained and the number of cycles to fatigue crack initiation is calculated for each location, based on which the most decisive location and the crossing life is determined. The results of the numerical simulations are presented and discussed.

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