Early Detection and Identification of Fatigue Damage in Thrust Ball Bearings by an Acoustic Emission Technique

Alan Hase

doi:10.3390/lubricants8030037

Abstract

As rolling bearings are widely used in various machines, there is a strong need to detect any problems as early as possible. Although vibration analysis is commonly used in the diagnosis of rolling bearings, it is possible that the failure of such bearings might be detected earlier by an acoustic emission (AE) technique. Methods for detecting potential fatigue damage in a thrust ball bearing by AE signal analysis and by vibration analysis were compared. For the AE signal analysis, the maximum amplitude and the frequency spectrum were used to detect and identify fatigue damage in the bearing. Features of AE signals detected when a defect was artificially formed on the raceway surface of a bearing by using a Vickers hardness tester were also examined. The AE technique detected initial cracks due to fatigue damage earlier than the vibration technique. Additionally, AE signals were always detected during bearing fatigue tests, but the AE signals detected during the running-in process, crack initiation, crack propagation, and flaking all contained different frequency components. Furthermore, the correlation map between the frequency spectra of AE signals and deformation and fracture phenomena (friction and wear modes) was updated by adding the new findings of this study.

Highlights

Thrust ball bearings are used worldwide in automobiles, aircraft, machine tools, and home appliances
The bearing fatigue test was ended when flaking on both the shaft washer and the housing washer was confirmed
There were no significant changes in the amplitude of either the acoustic emission (AE) signal or the vibration signal

Summary

Introduction

Thrust ball bearings are used worldwide in automobiles, aircraft, machine tools, and home appliances. Fatigue accumulates inside the materials of these bearings, causing minute internal cracks to form. These cracks propagate until they eventually reach the surface and expand, causing damage in whichever part of the material in the surface of the bearing peels off. A bearing that shows such peeling damage has reached its end of lifetime and requires replacement by a new one. The lifetime of a rolling bearing is defined as the time until rolling fatigue results in flaking of the contact surface between the inner or outer ring and the rolling elements. Bearings incorporated in actual machines can be damaged as a result of inadequate lubrication before flaking occurs, and might become unusable as a result. The surface of machine elements is mechanically affected by machining, unlike the deeper parts of the material

Methods

Results

Conclusion