THE USE OF VIBRATION MONITORING IN DETECTING THE INITIATION AND PREDICTION OF CORRUGATIONS IN ROLLING-SLIDING CONTACT WEAR

Vibration displacements and accelerations have been monitored on a mod ified Amsler machine during the dry rolling-sliding wear testing of ra il steels. Certain combinations of contact stress and creepage lead to periodic circumferential surface deformations of the test discs, term ed corrugations. The low frequency corrugations are defined as facets. Dramatic facets have occurred at 500 MPa maximum Hertzian contact str ess and 10% creepage, in the frequency band ranging from 1-100 Hz, wit h a typical facet frequency initiated at 58.25 Hz. No higher frequency corrugations occurred during the test run, unlike previous tests (J.E . Garnham, J.R. Brightling and J.H. Beynon, Wear, 124 (1988) 45-63).Th e evolution of the surface deformation was observed by surface profilo metry, as well as by monitoring the facet vibration component trend, a nd a good correlation between the two has been found. Aslo, a signific ant correlation between the predominant peaks of the displacement spec tra and the higher harmonics of the rotation frequency have been detec ted, leading to conclusions concerning the mechanism of facet initiati on. At the end of the test the facets degenerated into pronounced ecce ntricities causing a high level component of the rotation frequency th at could easily be detected by following the evolution of the characte ristic component. The tests highlighted that the vibration displacemen t is more suitable for the monitoring of rolling-sliding contact defec ts than is the acceleration, which tends to emphasise the high frequen cy components. Vibration monitoring is shown to be a proper and powerf ul tool for the early detection of facet initiation.