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摘要
The realistic description of the wheel-rail interaction is crucial in railway systems because the contact forces deeply influence the vehicle dynamics, the wear of the contact surfaces and the vehicle safety. In the modelling of the wheel-rail contact, the degraded adhesion represents a fundamental open problem. In fact an accurate adhesion model is quite hard to be developed due to the presence of external unknown contaminants (the third body) and the complex and highly non-linear behaviour of the adhesion coefficient; the problem becomes even more complicated when degraded adhesion and large sliding between the contact bodies (wheel and rail) occur. In this work the authors describe an innovative adhesion model aimed at increasing the accuracy in reproducing degraded adhesion conditions. The new approach has to be suitable to be used inside the wheel-rail contact models usually employed in the multibody applications. Consequently the contact model, comprising the new adhesion model, has to assure both a good accuracy and a high numerical efficiency to be implemented directly online within more general vehicle multibody models (e.g. in Matlab-Simulink or Simpack environments). The model studied in the work considers some of the main phenomena behind the degraded adhesion: the large sliding at the contact interface, the high energy dissipation, the consequent cleaning effect on the contact surfaces and, finally, the adhesion recovery due to the external unknown contaminant removal. The new adhesion model has been validated through experimental data provided by Trenitalia S. p. A. and coming from on-track tests carried out in Velim (Czech Republic) on a straight railway track characterised by degraded adhesion conditions. The tests have been performed with the railway vehicle UIC-Z1 equipped with a fully-working Wheel Slide Protection (WSP) system. The validation showed the good performances of the adhesion model both in terms of accuracy and in terms of numerical efficiency. In conclusion, the adhesion model highlighted the capability of well reproducing the complex phenomena behind the degraded adhesion.
- 出版日期2014-4
