Abstract
Surface initiated rolling contact fatigue (RCF), mainly characterized by cracks and material stripping, is a common type of damage to turnout rails, which can not only shorten service life of turnout but also lead to poor running safety of vehicle. The rail surface initiated RCF of turnouts is caused by a long-term accumulation, the size and distribution of which are related to the dynamic parameters of the complicated vehicle-turnout system. In order to simulate the accumulation of rail damage, some random samples of dynamic parameters significantly influencing it should be input. Based on the three-level unreplicated saturated factorial design, according to the evaluation methods of H, P and B statistic values, six dynamic parameters that influence the rail surface initiated RCF in turnouts, namely running speed of vehicle, axle load, wheel-rail profiles, integral vertical track stiffness and wheel-rail friction coefficient, are obtained by selecting 13 dynamic parameters significantly influencing the dynamic vehicle-turnout interaction as the analysis factors, considering four dynamic response results, i.e., the normal wheel-rail contact force, longitudinal creep force, lateral creep force and wheel-rail contact patch area as the observed parameters. In addition, the rail surface initiated RCF behavior in turnouts under different wheel-rail creep conditions is analyzed, considering the relative motion of stock/switch rails. The results show that the rail surface initiated RCF is mainly caused by the tangential stress being high under small creep conditions, the normal and tangential stresses being high under large creep conditions, and the normal stress being high under pure spin creep conditions.
Highlights
Turnouts are essential components of railway facilities
In the previous work [1], Kassa and Nielsen presented axle load, wheel–rail friction coefficient, and wheel/rail profiles as the parameters which could affect the performance of railway turnout significantly
The dynamic parameters which can significantly influence turnout rail surface initiated rolling contact fatigue (RCF) are selected according to the three-level unreplicated saturated factorial design method
Summary
Turnouts are essential components of railway facilities. A turnout consists of a switch panel, a closure panel and a crossing panel [1]. In order to achieve vehicle transfer, the switch rail and point rail are designed as variable cross-section rails, transferring the wheels between the stock rail and switch rail and between the wing rail and nose rail. During this process, skipping wheel-rail contact points can cause strong dynamic wheel-rail interaction, which is a main reason for wear, rolling contact fatigue (RCF) and accumulated plastic deformation [2,3,4] of turnout rail.
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