Onboard detection of railway axle bearing defects using envelope analysis of high frequency acoustic emission signals

Arash Amini,Mani Entezami,Mayorkinos Papaelias

doi:10.1016/j.csndt.2016.06.002

Arash Amini, Mani Entezami + Show 1 more

Open Access

https://doi.org/10.1016/j.csndt.2016.06.002

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Abstract

Railway wheelsets consist of three main components; the wheel, axle and axle bearing. Faults can develop on any of the aforementioned components, but the most common are related to wheel and axle bearing damages. The continuous increase in train operating speeds means that failure of an axle bearing can lead to very serious derailments, potentially causing human casualties, severe disruption in the operation of the network, damage to the tracks, unnecessary costs, and loss of confidence in rail transport by the general public. The rail industry has focused on the improvement of maintenance and online condition monitoring of rolling stock to reduce the probability of failure as much as possible. This paper discusses the results of onboard acoustic emission measurements carried out on freight wagons with artificially damaged axle bearings in Long Marston, UK. Acoustic emission signal envelope analysis has been applied as a means of effective tool to detect and evaluate the damage in the bearings considered in this study. From the results obtained it is safe to conclude that acoustic emission signal envelope analysis has the capability of detecting and evaluating faulty axle bearings along with their characteristic defect frequencies in the real-world conditions.

Highlights

Due to the increasing demand for safer and quicker rail transportation, rolling stock wheelsets operating under high axle loads, speed and heavy usage require more rigorous and reliable maintenance and inspection
Gradual deterioration of the structural integrity of wheels and axle bearings can increase the risk of failure and the possibility of delays, unnecessary costs and derailments, increased levels of vibration, noise and temperature produced by the axle bearing is a sign of a developing defect [2]
Acoustic emission (AE) in structural health condition monitoring is defined as the generation of elastic waves made by a sudden redistribution of molecules inside or on the surface of a material

Summary

Introduction

Due to the increasing demand for safer and quicker rail transportation, rolling stock wheelsets operating under high axle loads, speed and heavy usage require more rigorous and reliable maintenance and inspection. There has been much progress in on-line predictive maintenance of rotating machinery within the oil and gas and maritime industry These advances have led to a very reliable technique based mainly on trending of vibration signals and occasionally AE waveforms [3]. Faults in axle bearings can be categorised as distributed or local [4] Distributed defects such as surface roughness, waviness, etc., and the variation of contact force between rolling elements can increase the level of vibration and noise produced by the axe bearing. Localised defects, such as cracks, pits, spalls, etc., can generate impulses which can give rise to short duration vibration or AE signals [5]. Vibration data analysis was carried out using Ensemble Empirical Mode Decomposition (EEMD) and Hilbert marginal spectrum [6]

Theoretical background

Acoustic emission signal envelope analysis technique

Laboratory testing

Field trial testing

Conclusions