Impact generating mechanisms in damaged rolling element bearings

Standard condition monitoring techniques for assessing the health of rolling element bearings are widely used in numerous engineering industries. It is well known that the appearance of impulses in measured acceleration signals indicates the presence of a defect within a bearing. Although a large amount of technical content related to the signal processing of measured time-domain signals has been published in the literature and new data analysis methods are continued to be developed and enhanced, the mechanism by which the defect-related impulses are generated has received much less attention and has not been investigated in detail. This paper provides an explanation of the mechanisms by which defect-related impacts are produced in damaged rolling element bearings on the basis of findings from numerical modelling conducted using an explicit dynamics finite element software package, LS-DYNA. Indepth analysis of the numerically obtained impact-contact forces between the rolling elements and raceways of a bearing, which are not measured in practice, are presented in this paper.