A numerical model of a HIL scaled roller rig for simulation of wheel–rail degraded adhesion condition

Abstract

PLEASE SCROLL DOWN FOR ARTICLEFull terms and conditions of use: http://www.tandfonline.com/page/terms-andconditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Scaled roller rigs used for railway applications play a fundamental role in the development of new technologies and new devices, combining the hardware in the loop (HIL) benefits with the reduction of the economic investments. The main problem of the scaled roller rig with respect to the full scale ones is the improved complexity due to the scaling factors. For this reason, before building the test rig, the development of a software model of the HIL system can be useful to analyse the system behaviour in different operative conditions. One has to consider the multi-body behaviour of the scaled roller rig, the controller and the model of the virtual vehicle, whose dynamics has to be reproduced on the rig. The main purpose of this work is the development of a complete model that satisfies the previous requirements and in particular the performance analysis of the controller and of the dynamical behaviour of the scaled roller rig when some disturbances are simulated with low adhesion conditions. Since the scaled roller rig will be used to simulate degraded adhesion conditions, accurate and realistic wheel-roller contact model also has to be included in the model. The contact model consists of two parts: the contact point detection and the adhesion model. The first part is based on a numerical method described in some previous studies for the wheel-rail case and modified to simulate the three-dimensional contact between revolute surfaces (wheel-roller). The second part consists in the evaluation of the contact forces by means of the Hertz theory for the normal problem and the Kalker theory for the tangential problem. Some numerical tests were performed, in particular low adhesion conditions were simulated, and bogie hunting and dynamical imbalance of the wheelsets were introduced. The tests were devoted to verify the robustness of control system with respect to some of the more frequent disturbances that may influence the roller rig dynamics. In particular we verified that the wheelset imbalance could significantly influence system performance, and to reduce the effect of this disturbance a multistate filter was designed.

An innovative hardware in the loop architecture for the analysis of railway braking under degraded adhesion conditions through roller-rigs

“…General architecture of the HIL system. especially developed by the authors for this kind of application is used [20][21][22]. The mechanical and electrical characteristics of the vehicle [11,12] and of the roller-rig [14,15] are directly provided by Trenitalia and RFI.…”

“…Firstly, all the contact points P c l=r of each wheel-roller pair are detected. Some innovative procedures have been recently developed by the authors [20][21][22]; the new algorithms are based on the reduction of the algebraic contact problem dimension through exact analytical techniques [23]. Secondly, the normal contact problem is solved through the Hertz theory [29] to evaluate the normal Fig.…”

“…The inputs of the test-rig are the roller control torques while the outputs are the longitudinal reaction forces measured on the roller supports and the measured angular velocities of the rollers; the virtual railway vehicle model (software), representing the model used to simulate the vehicle behaviour on the rails under different adhesion conditions [16,20] and designed for a realtime implementation. This 2D multibody model simulates the longitudinal dynamics of the vehicle while an innovative 2D adhesion model especially developed [16,17] to accurately reproduce the real behaviour of the adhesion coefficient during braking phases under degraded adhesion conditions.…”

“…To reduce these costs, the performances of braking subsystems are traditionally investigated by means of full-scale roller-rigs [1][2][3][4]. Nevertheless, in case of degraded adhesion, the use of roller-rigs is still limited to few applications (full-scale roller-rigs for the study of the wear [5], HIL systems for WSP tests [16,20] and full-scale roller-rigs for locomotive tests [7,16,20]), since high slidings between rollers and wheelsets produce wear of the rolling surfaces. The wear of the flange can lead to the vehicle derailment, while the wear of the tread can produce hunting instability of the vehicle [6,8,24].…”

Development of an innovative wheel–rail contact model for the analysis of degraded adhesion in railway systems

“…The authors previously investigated this important topics on scaled railway test rigs [27], on full scale ones [29,41] and through ontrack railway tests [28,30].…”