Keywords: wheel-rail contact, impact force, crossing, optimisation, design, dip angle.

This paper is focused on an optimisation study of a GB 56E1 vertical acute crossing carried out as part of Shift2Rail project In2track2. The aim of the study was to achieve a design that helps minimise the impact load during wheel transfer and thus minimise the risk of degradation and fatigue failure of the cast crossing and subsequent cost of maintenance and replacement. The optimisation process achieved using the SnC_Design tool developed in Matlab, that fully accounts for the machining operations in use by industry suppliers to achieve the rail top surface shape, and it further allows a thorough assessment of the wheel-rail interaction by generating all necessary data for multibody simulations (MBS). The evaluation process is carried out on key output criteria generated from the simulations, such as dip angle, peak force and contact pressure. The tool allows the complex tri-dimensional optimisation and the many trade-offs to be solved. 120 alternative designs, varying nose topping and three additional parameters defining the wing rail shape, were assessed via a total of 2880 simulations cases. A candidate design was selected, showing 29% (facing) and 19% (trailing) increased performance with respect to the current crossings used in UK network for a 56kg rail crossing. This work also shows that replacing multibody simulations by kinematic analysis, where the dip angle or other measure is accurately determined, could lead to quicker solution but it was shown to have strong limitations, so is the dip angle criteria currently used by industry.

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