Towards intelligent dressing

The aim of this article is to state the principles of an intelligent monitoring and control system for the grinding machine, comprising the dressing process as well as grinding stability.     

Effect of liquid high positive friction (HPF) modifier on wheel-rail contact and rail corrugation

This paper presents an experimental study on the influence of HPF friction modifier on rail corrugation. The tests were carried out on a curve section of a commuter line, where corrugation appeared in the inner rail of the curves. The influence of HPF on wheel-rail contact forces has been studied based on acceleration measurements on the rail. These measurements were carried out with and without corrugation on the rail.Also, in order to compare the corrugation levels developed with and without the HPF, the evolution of corrugation was analyzed for this particular curve. The corrugation amplitudes and wavelengths were studied. It was found that the application of HPF substantially reduces the acceleration levels on the rail in vertical and lateral directions and delays the corrugation growth.     

Investigation of the influence of rail pad stiffness on rail corrugation on a transit system

This paper presents a study on the influence of rail pad stiffness on rail corrugation in an underground line. The paper includes a theoretical analysis justifying the rationale behind the modification of the pad stiffness to reduce corrugation levels, as well as a set of corrugation measurement results took on a test curve section during a period 19 months. The aim of the work is to demonstrate clearly that this treatment, studied by other authors like Ilias [H. Ilias, The influence of railpad stiffness on wheelset/track interaction and corrugation growth, J. Sound Vib. 227 (1999) 935-948], works on a metro system. In this study, the conventional rail pads on a test curve were substituted by softer pads. In order to examine the influence of new rail pads on corrugation, the rail profile was measured before and after the track modifications, during the same period of time. For both situations, wavelengths and amplitudes were analyzed and compared. It was found that soft pads reduce corrugation growth and eliminate one of the wavelengths developed when using stiff pads. The theoretical results were obtained from a model developed by Tassilly and Vincent [E. Tassilly, N. Vincent, Rail corrugations: analytical model and field tests, Wear 144 (1991), 153-161; E. Tassilly, N. Vincent, A linear model for corrugation of rails, J. Sound Vib. 150 (1991) 25-45]. This linear model for the corrugation of rails was used to predict the frequency bands in which corrugations are likely to appear. The track and the wheelset dynamics were studied both experimentally and theoretically. Quasi-static wheel/rail forces and creepages have been obtained with a multibody model of a metro unit. The methodology followed to compare the theoretical and experimental results is based on the work carried out by Grassie and Elkins [S.L. Grassie, J.A. Elkins, Rail corrugation on north american transit systems, Vehicle System Dyn. 28 (1998) 5-17]. The correlation between simulated and experimentally measured corrugation wavelengths appearing in the inner rails of curves is analyzed, and the corrugation mechanism is explained.