Multibody modelling of railway vehicles: an innovative elastic wheel - rail contact model

The wheel – rail contact analysis plays a fundament al 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 for ces, position and shape of the contact patch, stress and strain) and a general handling of the multiple contact. The model has also to assure high numerical efficiency and a good compati bility with commercial multibody software (Simpack Rail, Adams Rail). In this work the authors intend to present an innov ative elastic wheel – rail contact model that satisfies the previous specifics. The model co nsiders the wheel and the rail as elastic deformable bodies and requires the numerical soluti n of the Navier’s elasticity equation. The contact between wheel and rail has been describ ed by means of suitable analytical contact conditions. Subsequently the contact model has been inserted within the multibody model of a benchmark railway vehicle (the Mancheste r Wagon) in order to obtain a complete model of the wagon. The whole model has been implem ent d in the Matlab/Simulink environment. Finally numerical simulations of the v ehicle dynamics have been carried out on many different railway tracks with the aim of evalu ating the performances of the model. The multibody model of the same vehicle (this time equipped with a standard contact model) has been then implemented also in Simpack Ra il. The comparison between the results obtained by the Matlab model and those obtained by the Simpack model has allowed an accurate and reliable validation of the new contact model. In conclusion the main purpose of the authors is to achieve a better integration between the differential modeling and the multibody modelin g. This kind of integration is almost absent in literature (especially in the railway fie ld) due to the computational cost and to the memory consumption. However it is very important be cause only the differential modeling allows an accurate analysis of the contact problem (in terms of contact forces, position and shape of the contact patch, stress and strain) whil e t e multibody modeling is currently the standard in the study of the railway dynamics. Silvia Magheri, Monica Malvezzi, Enrico Meli and And rea Rindi 2