Keywords: multibody modeling, wheel-rail contact, contact between elastic bodies.

The wheel-rail contact analysis plays a fundamental role in the multibody modeling of railway vehicles. A good contact model must provide an accurate description of the global and local contact phenomena (contact forces, position and shape of the contact patch, stresses and displacements) and a general handling of the multiple contact. The model has also to assure high numerical efficiency (in order to be implemented directly online within multibody models) and good compatibility with commercial multibody software (Simpack Rail, Adams Rail).

In this work the authors present an innovative elastic wheel-rail contact model that satisfies the previous specifics. The model considers the wheel and the rail as elastic deformable bodies and requires the numerical solution of Navier's elasticity equation. The contact between wheel and rail has been described by means of suitable analytical contact conditions. Subsequently the contact model has been inserted within the multibody model of a benchmark railway vehicle (the Manchester Wagon [1]) in order to obtain a complete model of the wagon. The whole model has been implemented in the Matlab environment. Finally numerical simulations of the vehicle dynamics have been carried out on many different railway tracks with the aim of evaluating the performance of the model.

In conclusion the main purpose of the authors is to achieve a better integration between the differential modeling and the multibody modeling. This kind of integration is almost absent in the literature (especially in the railway field) due to the computational cost and to the memory requirements. However it is very important because only the differential modeling allows an accurate analysis of the contact problem (in terms of contact forces, position and shape of the contact patch, stresses and displacements) while the multibody modeling is currently the standard in the study of the railway dynamics [2,3,4,5].

1

S. Iwnicki, "The Manchester benchmarks for rail vehicle simulators", Swets & Zeitlinger, Lisse, Netherlands, 1999.

2

K.L. Johnson, "Contact mechanics", Cambridge University Press, Cambridge, England, 1985.

3

N. Kikuchi, J.T. Oden, "Contact problems in elasticity", SIAM Studies in Applied Mathematics, Philadelphia, Pennsylvania, 1988.

4

P. Wriggers, "Computational contact mechanics", Wiley & Sons, Hoboken, New Jersey, 2002.

5

O. Zienkiewicz, "The finite element method in engineering science", McGraw-Hill, New York, 1988.

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