Abstract
A metamodel considering material plasticity is presented for computationally efficient prediction of wheel–rail normal contact in railway switches and crossings (S&C). The metamodel is inspired by the contact theory of Hertz, and for a given material, it computes the size of the contact patch and the maximum contact pressure as a function of the normal force and the local curvatures of the bodies in contact. The model is calibrated based on finite element (FE) simulations with an elasto-plastic material model and is demonstrated for rail steel grade R350HT. The error of simplifying the contact geometry is discussed and quantified. For a moderate difference in contact curvature between wheel and rail, the metamodel is able to accurately predict the size of the contact patch and the maximum contact pressure. The accuracy is worse when there is a small difference in contact curvature, where the influence of variation in curvature within the contact patch becomes more significant. However, it is shown that such conditions lead to contact stresses that contribute less to accumulated plastic deformation. The metamodel allows for a vast reduction of computational effort compared to the original FE model as it is given in analytical form.
Highlights
Railway turnouts are subjected to a severe load environment, in particular in the switch and crossing panels, see, e.g., [8, 18, 23]
CHARMEC/Division of Material and Computational Mechanics, Chalmers University of Technology, SE‐412 96 Gothenburg, Sweden by the downwards–upwards motion experienced by the wheel as it rolls along the wing rail and over to the crossing rail or vice versa
The metamodel can take into account plastic deformations and, is an enhancement of the Hertzian solution
Summary
Railway turnouts (switches & crossings, S&C) are subjected to a severe load environment, in particular in the switch and crossing panels, see, e.g., [8, 18, 23]. To represent the variation in traffic that a given crossing is subjected to, a distribution of load parameters such as wheel profile, train speed, axle load and wheel–rail friction coefficient needs to be accounted for This in turn leads to a wide range of contact load scenarios with different magnitudes of wheel–rail contact load occurring at various positions along the crossing panel. Each of these scenarios needs to be accounted for by an FE simulation in part II of the methodology, which, due to the required combination of high mesh resolution in three dimensions and non-linear material model, is computationally expensive. A comparison between calculated contact conditions for elastic material when applying an in-house implementation of Kalker’s variational method [21] or an FE model, using either the nominal geometry
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