Keywords: rolling contact, head check, finite element simulation, equivalent stress field, curving, worn profiles.

This paper deals with the prerequisites for the initiation of the rolling contact fatigue process of the upper regions of railheads being in direct contact with the rolling wheels. The stress field is analysed, pointing out the conditions of crack evolution. The input data of the contact model contains material characteristics coming from laboratory tests and reflects real vehicle and track parameters. The computations presented aim to give indication of worst possible cases - the loads that provide the maximum stress levels in the railhead. For the simulated wheel/rail contact cases, the usually non-Hertzian deformation field is computed by using the program CONTACT. A Matlab code is then described for pre-processing the finite element simulations of special contact cases. The finite element model simulates the possible plastic behaviour of the rail material and the stress distribution in the affected zones. The results of twenty-seven wheel/rail contact cases have been evaluated and compared to each other. Conclusions are drawn with respect to the main important factors that influence head check initiation - such as vehicle speed, track curvature and different wheel/rail profile combinations.

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