Experimental Study and Phenomenological Laws of Some Nonlinear Behaviours of the Wheel–Rail Contact Associated with the Deshunting Phenomenon

International audienceA widely used technique for locating the position of a train during its journey involves electrical detection: on a section of track, the train closes (“shunts”) a circuit dedicated to its location via its wheels and axles. The quality of the wheel–rail contact is therefore particularly important for signalling management and traffic control. In this paper, we show that the current flowing through the track circuit induces a permanent modification and a nonlinear, frequency-dependent behaviour of the electrical contact. We propose an analytical expression that describes the evolution of the measured voltage as a function of current and frequency for these nonlinear behaviours. This behavioural law was obtained using experimental measurements on a real train and could therefore be integrated into a global model describing the track system

Contribution to the determination of the thermal contact resistance : algorithm of evaluation of the number of asperities involved in the contact

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International benchmarking of longitudinal train dynamics simulators: results

This paper presents the results of the International Benchmarking of Longitudinal Train Dynamics Simulators which involved participation of nine simulators (TABLDSS, UM, CRE-LTS, TDEAS, PoliTo, TsDyn, CARS, BODYSIM and VOCO) from six countries. Longitudinal train dynamics results and computing time of four simulation cases are presented and compared. The results show that all simulators had basic agreement in simulations of locomotive forces, resistance forces and track gradients. The major differences among different simulators lie in the draft gear models. TABLDSS, UM, CRE-LTS, TDEAS, TsDyn and CARS had general agreement in terms of the in-train forces; minor differences exist as reflections of draft gear model variations. In-train force oscillations were observed in VOCO due to the introduction of wheelâ\u80\u93rail contact. In-train force instabilities were sometimes observed in PoliTo and BODYSIM due to the velocity controlled transitional characteristics which could have generated unreasonable transitional stiffness. Regarding computing time per train operational second, the following list is in order of increasing computing speed: VOCO, TsDyn, PoliTO, CARS, BODYSIM, UM, TDEAS, CRE-LTS and TABLDSS (fastest); all simulators except VOCO, TsDyn and PoliTo achieved faster speeds than real-time simulations. Similarly, regarding computing time per integration step, the computing speeds in order are: CRE-LTS, VOCO, CARS, TsDyn, UM, TABLDSS and TDEAS (fastest)