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Squats are rather complex failure mechanisms in rails and challenge railway operators all over the world, thus calling for a detailed investigation of squats by means of finite element analysis to locate the initiation and propagating mechanisms. In this work, a cyclic three-dimensional (3D) finite element model of a wheel-rail contact including an initial penny-shaped defect is used. This work presents the implementation of the starting penny-shaped crack in the rail for a wheel-rail simulation by utilising a submodel strategy. Moreover, viable evaluation options are shown. In the future, this set-up will help to assess multiple crack positions and possible squat growth mechanisms. [ABSTRACT FROM AUTHOR]

To tackle the problem of various types of rail damage, such as rolling contact fatigue (RCF) or wear, a profound knowledge of the occurring mechanisms is necessary. This paper presents a newly developed full-scale test rig experiment that involves inserting softer pins into the rail head. These tests help deepen our understanding of shear deformation in rail steels. Furthermore, a finite element (FE) simulation approach is introduced that can be related to the test rig experiments. With these experiments, in combination with the FE simulation, valuable information regarding the plastic deformation can be obtained. This methodology allows predictions regarding a rail's material behaviour during cyclic wheel loading. Moreover, it enables an effective and rapid qualitative material assessment, reducing the costs of expensive and time-consuming experiments. [ABSTRACT FROM AUTHOR]

A dynamic 3D finite element model for the calculation of profile degradation in the switch panel is presented. The model includes the contact between wheel and rail, as well as the contact between switch rail and stock rail to allow an elastic relative movement between the two rails. Break-outs of the switch rail tip can be facilitated by this relative movement and the stresses and strains at this interface are calculated. The profile degradation of the switch rail due to contact loading between wheel flange and switch rail is numerically simulated considering the cyclic plastic deformation of the rail material. The sliding wear is evaluated separately and superimposed to the geometrical change caused by the plastic deformation. [ABSTRACT FROM AUTHOR]

In this study, the initiation of subsurface damage due to the impact of new and worn wheels on differently deformed crossing nose geometries is calculated using the Dang-Van criterion. Three crossings with different materials (manganese steel, chromium-bainitic steel, and tool steel) were cyclically loaded in an FE crossing model reported in a previous study to evaluate the run-in state of plastic deformation. The impacts of the wheels on the deformed crossings were then calculated by considering the behaviour of an elastic material. This parametric study showed the effects of different velocities, axle loads, and wheel types on the vertical contact forces, contact pressures, and Dang-Van damage parameters. Additionally, the ability of manganese steel crossings to withstand unfavorable load situations was observed by including plastic material behavior and considering material history, such as residual stresses and hardening. [ABSTRACT FROM AUTHOR]