A full explicit FEM simulation of wheelset passing through switch panel is presented. The real 3D geometry of the switch panel is used, both vertical and lateral response are taken into consideration. The dynamic interaction is analysed and it is found that the damage mechanism on the switch blade and stock rail is a complex interaction of wear, fatigue and impact, which can be well described by explicit FEM simulation. Parametric analysis of running speed, traction coefficient and the friction coefficient between switch blade gauge surface and wheel flange indicate that decreasing running speed can help to reduce the damage on switch panel. The traction coefficient has little influence on the maximum impact response, but a higher traction coefficient is beneficial for eliminating the dynamic response after the maximum impact response point. The influence of the friction coefficient on the dynamic impact response is not significant, but a lower friction coefficient is favourable for decreasing the wear damage on the switch blade and increasing running safety. This work can provide a good understanding of the interaction on switch panel and give theoretical support for maintenance and improving the design.

Stochastic fatigue damage of a metro switch blade is studied with a combination of explicit finite element model (FEM), multiaxial fatigue criterion, and statistical analysis. The explicit FEM is used to reproduce dynamic procedure and to provide detailed stress/strain state variation. A multiaxial fatigue criterion proposed recently is extended to 3D conditions for fatigue prediction. The influence of stochastic impact position is considered by statistical analysis. After analysis, the formation of the serious unstable crack (continuous bites) on the switch blade can be revealed. From the perspective of service life, increasing traction coefficient and decreasing friction coefficient between wheel flange and switch blade gauge surface are beneficial but not significant. However, a speed increase from 36 to 54 km/h can lead to 40% reduction in service life. This work enhances the cognition of damage mechanism on switch blade and provides theoretical foundation for service life design and maintenance operation.

A new fatigue parameter is proposed, which provides a new way of thinking to assess fatigue damage problems. The complete stress state at a certain material point, i.e., taking into account any material plane at that point, is included in the method. The influence of tension and compression state and also the mean stress are also included. Some experiments with different materials and loading conditions are used to validate the capabilities of the proposed method. The results show that the method provides good predictions for axial cyclic and/or torsion cyclic conditions with zero or nonzero mean stresses, in-phase and out-of-phase, different shapes of the specimen, loading waveform and loading path.

In this article, a universally applicable multiaxial fatigue criterion in 2D cyclic loading is proposed, which can be used for a great variety of materials and loading conditions. A strain-based fatigue parameter is defined and, at the same time, a new failure model is proposed to overcome the weaknesses of other mechanisms used previously. In addition, the influence of non-proportional loading, maximum, minimum and mean loading, the influence of both normal and shear components, Poisson effect, different failure types, etc. can also be taken into consideration. A huge number of materials and loading conditions are used to validate the capabilities of the proposed methodology. The results show that the new multiaxial fatigue criterion provides excellent life predictions for all the materials and loading conditions used in this work. The proposed approach can be regarded as a universally applicable multiaxial fatigue criterion in 2D cyclic loading.

A multiaxial fatigue criterion recently developed by the authors for 2D conditions is extended here to 3D situations and applied to predict fatigue damage in rail welded joints with the help of an explicit finite element model. Contact theory and axle box acceleration response in frequency domain are used to validate the finite element model. The influence of depth and length of the welded joints is analyzed. It is found that fatigue damage is more severe with shorter and deeper welded joints. When the length of the welded joints is less than 150 mm, fatigue damage is greatly increased with the increasing of the depth. When the depth is less than 0.1 mm, fatigue damage is not relevant, regardless of the length. When the depth is greater than 0.3 mm, fatigue damage increases significantly with the decreasing of the joint length, especially when the length is less than 150 mm. When the welded joints are long enough, the depth restriction can be relaxed. This work can provide guidance and theoretical support for maintenance and repair of rail welded joints.

A new multiaxial fatigue criterion is proposed that takes into account the influence of material properties and loading conditions on the direction of the critical fatigue plane. Poisson's effect, normal and shear strain energies, both elastic and plastic, and material hardening can be taken into account in this criterion. Ten different materials subjected to various loading paths with different test-sample geometries are used to validate the capabilities of the proposed approach. The comparison with other commonly used energy-based criteria is also presented. The results show that the proposed criterion provides very good predictions for all the analysed materials and loading conditions (within a factor of two) used in this work. The error in life prediction with the present approach also compares favourably with respect to other criteria available in the literature.

A multiaxial fatigue criterion is proposed, which can be seen as a modification of a previous criterion presented by the authors. The influence of the unique material state can be taken into consideration, as well as the range and mean value of the variables involved in the fatigue parameter for depicting the influence of the loading condition. Definitions of the out-of-phase failure and out-of-phase failure angle are proposed, as well as an out of-phase failure parameter that can be used to express the interdependent relationship with the out-of-phase failure, in both normal-type and shear-type failure. An explicit physical interpretation of different failure types is proposed. After validation and comparison with experimental results for different loading conditions and materials, it is concluded that the prediction ability of this modified multiaxial fatigue criterion is better than that of the original Lu's criterion, as well as than those of the other commonly used multiaxial fatigue criteria.

A new approach for the definition of the critical plane and a new energy-based multiaxial fatigue parameter are proposed in this work. The normal strain energy and shear strain energy on two orthogonal material planes are used to predict fatigue damage in multiaxial fatigue loading. The influence of the Poisson effect, mean normal strain energy and the different contribution of the compressive and tensile normal strain energies are accounted for. An energy-based parameter is defined which explains the different effects of the total strain energy on different material directions. Experimental data are used to validate the capabilities of this new multiaxial fatigue parameter, including 10 materials and 33 loading paths, which cover most of the commonly used loading conditions in multiaxial fatigue tests. The results show that the proposed multiaxial fatigue parameter gives good predictions (within a life factor of two) for most of these materials and loading paths. (C) 2017 Elsevier Ltd. All rights reserved.

A new method for predicting crack plane direction in high-cycle multiaxial fatigue is proposed. This method considers material properties and loading conditions. Two situations are considered: (i) in-phase loading, where the crack plane direction only depends on the loading condition and material properties have little influence on it, and (ii) out-of-phase loading, where the crack plane direction is affected by both loading conditions and material properties. The prediction accuracy is assessed by comparison with several experimental results, including different loading conditions and materials. The results show that the proposed method provides a good prediction capability for these experiments.

Purpose This article focuses on a novel Advanced Train LocAtion Simulator (ATLAS) for on-board railway location using wireless communication technologies, such as satellite navigation and location based systems. ATLAS allows the creation of multiple simulation environments providing a versatile tool for testing and assessing new train location services. This enhancement reduces the number of tests performed in real scenarios and trains, reducing the cost and development time of new location systems as well as assessing the performance level for given tracks. Methods The simulation platform is based on modular blocks, where each block can be replaced or improved. The platform uses Monte Carlo Simulation to generate results with statistical significance. This implementation allows the modification of the development platform to cover multiple requirements, such as, ranging errors in the input parameters or including other positioning technologies. In this paper, the generated input parameter errors have been taken from the results of the field tests realized by the 3GPP ensuring the validity of the used parameter errors. However, these could be easily adapted by the user to particular characterized environments. Results Case studies for the validation of ATLAS will be also introduced, including preliminary results related to the use of Global System for Mobile communications in Railway (GSM-R) and Universal Mobile Telecommunications System (UMTS) technologies for positioning. The validation stage provides a way to test the platform functionalities and verify its flexibility. Conclusions The versatility of the platform to perform simulations using same configuration parameters for different case studies can be highlighted. Furthermore, first conclusions are drawn from the obtained results. The characterization of the infrastructure for the simulation and the performance improvement of the location systems in the tunnels (e.g., by including Inertial Measurement Unit (IMU)) are necessary to achieve accuracy levels that can be valid for ETCS level 3.