Rolling Contact (rolling + contact)

Distribution by Scientific Domains


Selected Abstracts


Plastification and Damage in Wheel-Rail Rolling Contact , Case Study on a Crossing

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005
Martina Wiest
A fully three-dimensional, dynamic model for a wheel running over a crossing is developed using an explicit finite element program. The full mass of the wheel and the crossing and elastic-plastic material behaviour are considered. The damage in the contact area is investigated with a very dense mesh taken from the dynamic model using a submodelling technique. With this kind of calculations the stresses and strains produced in the wheel and the crossing during the cross-over process can be determined, as well as the respective reaction forces in the bedding and the axle. Calculations for different crossing-geometries are performed. Finally a damage indicator is introduced to identify the probable location of crack initiation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Relative fatigue life estimation of cylindrical hollow rollers in general pure rolling contact

LUBRICATION SCIENCE, Issue 1 2008
Wisam M. Abu Jadayil
Solid and hollow cylindrical rollers in pure rolling contact have been modelled. The two rollers are subjected to a combined normal and tangential loading. The tangential loading is one-third of the normal loading value. The finite element package, ABAQUS, is used to study the stress distribution and the resulting deformations in the bodies of the rollers. Then the Ioannides,Harris fatigue life model for rolling bearings is applied on the ABAQUS numerical results to investigate the fatigue life of the solid and hollow rollers. Using the fatigue life of the solid rollers as the reference fatigue life, the relative fatigue lives of hollow rollers are determined. Four main different hollowness percentages are been studied: 20, 40, 60 and 80%. The hollowness percentage is the ratio of the diameter of the hole to the outer diameter of the cylinder. For each of those hollowness percentages, two cases are studied , when the two rollers in contact are hollow and when one hollow roller is in contact with a solid roller. This study includes two main models: Model 1, where the two cylindrical rollers in contact are of the same size, and Model 2, where the two rollers in contact are not of the same size. The estimated relative fatigue lives of hollow rollers showed a great improvement of the fatigue life compared with solid rollers under the same loading conditions. This was a result of the redistribution of stresses in the contact zone in the case of hollow rollers. Redistribution of stresses over a larger volume of the roller body decreased the peak stress and reduced the volume under risk. Increasing the hollowness percentage from 20 to 60% increased the flexibility of the roller, and better stress distribution was achieved, which resulted in improving the fatigue life. Although 80% of hollowness rollers have more flexibility than 60% of hollowness rollers, the bending stresses (,b) on the inner surface of the rollers tend to decrease the fatigue life. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Investigation of the physical mechanisms in rolling bearings during the passage of electric current

LUBRICATION SCIENCE, Issue 4 2005
A. Jagenbrein
Abstract With the increasing use of frequency converters as control units for electric motors, bearing failures caused by the passage of electric current through the bearings are more common. This paper discusses the most relevant parasitic current loops in frequency converter-driven motors that can lead to damage of bearing raceways or deterioration of lubricants. Electrical stray capacitances, which are inevitably present in any electric motor, in combination with the high-frequency components of the drive voltages, have been identified as the source of electric discharge machining (EDM) currents. Based on an EDM equivalent electric circuit, the passage of electric current through the rolling contact of a bearing is simulated. A set-up is introduced to initiate EDM processes in bearings under well-controlled electrical and mechanical conditions. The effect of EDM currents on bearing elements in the presence of different lubricants is studied. Initial results are presented. [source]