A three-dimensional (3-D) explicit dynamic finite element (FE) model is developed to simulate the impact of the wheel on the crossing nose. The model consists of a wheel set moving over the turnout crossing. Realistic wheel, wing rail and crossing geometries have been used in the model. Using this model the dynamic responses of the system such as the contact forces between the wheel and the crossing, crossing nose displacements and accelerations, stresses in rail material as well as in sleepers and ballast can be obtained. Detailed analysis of the wheel set and crossing interaction using the local contact stress state in the rail is possible as well, which provides a good basis for prediction of the long-term behaviour of the crossing (fatigue analysis). In order to tune and validate the FE model field measurements conducted on several turnouts in the railway network in the Netherlands are used here. The parametric study including variations of the crossing nose geometries performed here demonstrates the capabilities of the developed model. The results of the validation and parametric study are presented and discussed.
ARTICLE HISTORY
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.
The procedure for analyzing turnout crossing performance is developed in this paper. The experimental and numerical analysis are both conducted to evaluate the dynamic behavior of the crossing and to further improve the crossing performance. Geometry and acceleration measurements are performed on common single turnouts in the Dutch railway network for analyzing the measured crossing performance and providing the input for numerical modeling. Meanwhile, a three-dimensional finite element model of a whole wheelset rolling over the crossing has been developed. The wing rail and crossing nose geometry as well as the wheel geometry have been used in the model. The numerical responses of the model comprise the dynamic contact forces between the wheelset and the crossing, displacements of the wheelset and crossing as well as the local contact stress and strain distributions, by which the crossing performance is evaluated and the fatigue life of the crossing is predicted. By this approach further improvement of the crossing nose and wing rail geometry can be realized.
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