Entity

Time filter

Source Type

Optand, Sweden

Li M.,Swedish Transport Administration Trafikverket | Persson I.,AB DEsolver | Spannar J.,Swedish Transport Administration Trafikverket | Berg M.,KTH Royal Institute of Technology
Vehicle System Dynamics | Year: 2012

This paper studies the use of second-order derivatives of track irregularities (longitudinal level, LL) for assessing vertical track geometry quality. Both a single-degree-of-freedom and a three-DOF vehicle-track model are investigated in order to explain theoretically why from the aspect of vehicle-track dynamic interaction it is relevant to consider not only the amplitudes of LL but also their second-order derivatives (LL2). Simulation results are then presented to demonstrate that dynamic vertical track forces are more correlated with the second-order derivatives (LL2) than to the amplitudes (LL) themselves. A comparison of the power spectral density (PSD) spectra for typical track reveals that it is more convenient to use the PSD spectra for the second-order derivatives than for the amplitudes, as the curves for the second-order derivatives are flat within the short wavelength range. Finally, the practical use of derivatives within the maintenance management system in order to achieve improved assessment of track geometry quality is also discussed. © 2012 Copyright Taylor and Francis Group, LLC. Source


Persson I.,AB DEsolver | Nilsson R.,AB Storstockholms Lokaltrafik | Bik U.,AB Storstockholms Lokaltrafik | Lundgren M.,Interfleet Technology AB | Iwnicki S.,Manchester Metropolitan University
Vehicle System Dynamics | Year: 2010

In this paper, a genetic algorithm optimisation method has been used to develop an improved rail profile for Stockholm underground. An inverted penalty index based on a number of key performance parameters was generated as a fitness function and vehicle dynamics simulations were carried out with the multibody simulation package Gensys. The effectiveness of each profile produced by the genetic algorithm was assessed using the roulette wheel method. The method has been applied to the rail profile on the Stockholm underground, where problems with rolling contact fatigue on wheels and rails are currently managed by grinding. From a starting point of the original BV50 and the UIC60 rail profiles, an optimised rail profile with some shoulder relief has been produced. The optimised profile seems similar to measured rail profiles on the Stockholm underground network and although initial grinding is required, maintenance of the profile will probably not require further grinding. © 2010 Taylor & Francis. Source


Spiryagin M.,Central Queensland University | Duan K.,Central Queensland University | Wu Q.,Central Queensland University | Cole C.,Central Queensland University | And 2 more authors.
CM 2015 - 10th International Conference on Contact Mechanics of Wheel / Rail Systems | Year: 2015

The calculation of temperatures in the contact zone at the wheel and rail interface is a very complex and important issue for multidisciplinary studies. The knowledge of temperature in the contact interface between two bodies and with the possible presence of a third body layer allows making informed judgments on processes in areas such as lubricant choice, wear estimation, life cycle prediction, etc. This paper is focused on the development of a temperature modelling methodology in Gensys multibody code which also presents its implementation for the study of temperatures at various common areas of contact (top of rail, gauge corner and gauge face contacts). Under normal operational practice, all these contact areas have different coefficients of friction which should be characterised as velocity and slip dependant variables. In order to show the workability of the developed methodology, numerical experiments for a heavy haul locomotive equipped with a simplified bogie traction control has been performed on curved track, where a locomotive has been operated under maximum traction forces and with longitudinal and lateral coupler forces attached in order to take into account train dynamics. For these experiments, both new and worn rail profiles have been used. Limitations of the proposed methodology as well as proposed future work and further improvements are discussed. Source


Petrov V.,KTH Royal Institute of Technology | Berg M.,KTH Royal Institute of Technology | Persson I.,AB DEsolver
Vehicle System Dynamics | Year: 2014

In certification of new rail vehicles with respect to running characteristics, a wide variety of operating conditions needs to be considered. However, in associated test runs the wheel-rail friction condition is difficult to handle because the friction coefficient needs to be fairly high and the friction is also generally hard to assess. This is an issue that has been studied in the European project DynoTRAIN and part of the results is presented in this paper. More specifically, an algorithm for estimating the wheel-rail friction coefficient at vehicle certification tests is proposed. Owing to lack of some measurement results, the algorithm here is evaluated in a simulation environment which is also an important step towards practical implementation. A quality measure of the friction estimate is suggested in terms of estimated wheel-rail spin and total creep. It is concluded that, tentatively, the total creep should exceed 0.006 and the spin should be less than 1.0 m-1 for the algorithm to give a good friction estimate. Sensitivity analysis is carried out to imitate measurement errors, but should be expanded in further work. © 2014 Taylor & Francis. Source


Spiryagin M.,Central Queensland University | Wu Q.,Central Queensland University | Duan K.,Central Queensland University | Cole C.,Central Queensland University | And 2 more authors.
International Journal of Rail Transportation | Year: 2016

Calculation of the temperature in the contact zone at the wheel–rail interface is a very complex and important issue for multidisciplinary railway studies. The knowledge of temperature in the contact interface between two bodies, and with the possible presence of a third body interfacial layer, allows making informed judgments on processes in areas such as lubricant choice, wear estimation, life cycle prediction, etc. This paper focuses on development of a temperature modelling methodology in Gensys, and also presents its implementation for the study of temperatures at different contact points (top of rail, gauge corner, and gauge face contacts). In operational practice, all these mentioned contacts have different coefficients of friction which should be characterized as velocity and slip-dependent variables. To demonstrate the workability of the developed methodology, numerical experiments for a heavy haul locomotive equipped with a simplified bogie traction control system have been performed on curved track, where a locomotive has been operated under maximum traction forces and with longitudinal and lateral coupler forces attached in order to take into account train dynamics. Both new and worn rail profiles have been used. Limitations of the proposed methodology as well as proposed future work and further improvements are discussed. © 2016 Informa UK Limited, trading as Taylor & Francis Group Source

Discover hidden collaborations