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Lewis S.R.,University of Sheffield | Lewis R.,University of Sheffield | Olofsson U.,KTH Royal Institute of Technology | Eadie D.T.,Kelsan Technologies Corporation | And 2 more authors.
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | Year: 2013

Commercially available friction modifiers are used in many different countries that have widely different atmospheric conditions. These variations in atmospheric conditions lead to varying levels of railhead oxidation and debris build-up. Friction modifiers can be applied to the rail without any prior cleaning of the rail and this can lead to varying friction modifier/iron oxide ratios potentially affecting the performance of the friction modifier. This paper reports the results of an investigation that was performed to determine the effects of varying atmospheric and oxide conditions on the performance of friction modifiers. A pin-on-disk test rig with an attached environmental chamber was used for the study. Results show that relative humidity has a pronounced effect on the way in which the friction modifier affects friction levels, and also the amount of time it remains on the disk. This also depends on the concentration of oxide in the friction modifier. Glow discharge optical emission spectroscopy analysis was also carried out to assess the effect of the friction modifier and atmospheric conditions on the chemical composition of the surface of the disk. Results show that the depth of surface modification is vastly different depending on the conditions and level of railhead debris. © IMechE 2012.

Liu C.,Simon Fraser University | Liu C.,Kelsan Technologies Corporation | Rajapakse R.K.N.D.,Simon Fraser University
IEEE Transactions on Nanotechnology | Year: 2013

Nanoscale circular plates are encountered in several nanotechnology-based devices such as nanoelectromechanical systems. Structures are size dependent at nanoscale due to surface energy effects. It is possible to capture such size dependence through special continuum models. In this paper, the Gurtin-Murdoch continuum theory is applied to develop a new continuum mechanics model for static deformation of thin and thick circular nanoplates. The relevant governing equations are established from basic principles. It is shown that the governing equations possess a closed-form analytical solution that makes the current approach suitable for device analysis and design. A series of closed-form analytical solutions is presented for static bending of thin and thick plates under common static loading (uniformly distributed and center point) and boundary conditions (simply supported and clamped edges). The analytical solution for a thin plate supported by a linear elastic substrate is also presented. Deflection profiles of selected silicon and aluminum plates are presented and compared with the classical plate theory results to examine the salient features of mechanical response and influence of surface elastic moduli, surface residual stress, and boundary conditions. © 2002-2012 IEEE.

Vuong T.T.,University of Queensland | Meehan P.A.,University of Queensland | Eadie D.T.,Kelsan Technologies Corporation | Oldknow K.,Kelsan Technologies Corporation | And 3 more authors.
Wear | Year: 2011

In this paper, a recently proposed mechanics-based model for the wear coefficient of rail steels is experimentally validated and implemented to obtain useful predictive wear models for some popular railway steels. The model is then implemented to investigate the feasibility of top of rail (TOR) friction modifiers (FMs) for wear-type rail corrugation control. The experimental results confirm the analytical prediction of the first transition (step change in value) of the wear coefficient based on known conditions of creep and load. The implementation of the model under dry and friction-modified conditions shows a substantial reduction in the wear coefficient from 1.6×10-09kg/Nm to 0.34×10-09kg/Nm, respectively. This along with an approximate 50% reduction in friction coefficient, is predicted to result in substantial decreases in corrugation growth rate and grinding costs of ∼20 times under the experimentally measured conditions of friction modifiers. © 2010 Elsevier B.V.

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