Acoustic emission monitoring of rolling element bearings failures

Alshatti, Othman 2021. Acoustic emission monitoring of rolling element bearings failures. PhD Thesis, Cardiff University. Item availability restricted.

Preview	PDF - Accepted Post-Print Version Download (14MB) | Preview
	PDF (Cardiff University Electronic Publication Form) - Supplemental Material Restricted to Repository staff only Download (242kB)

Abstract

Acoustic emission (AE) is a condition monitoring technique used for rotating machinery components that is gaining ground in the industrial field, due to its sensitivity to high frequency range, which makes it advantageous compared with traditional vibration techniques in the detection of incipient damage at the early stages of failure. This thesis presents an investigation using three types of similarly-sized cylindrical roller bearings, yet with different characteristics and qualities on a high speed test rig, with maximum rotational speed set at 5980rpm. The bearings under investigation are normal clearance SKF Types NU202ECP and NU202EM budget bearing, NU202ECP/C3 with higher radial clearance. This work aims to investigate the healthy bearings characterisation tests to deliver a well-defined foundation of the AE signal results, as well their operational lubrication regimes. Secondly, to investigate the underlying early stages and presence of naturally propagated damage within a rolling element bearing under heavily loaded operational conditions. Lastly, to compare the results from the 3 types of bearings. The healthy bearing characterisation tests identified that load and speed influenced the generated AE signal, with speed having a greater impact on the AE signal. It has also shown that the higher radial clearance bearing generated lower levels of energy excitation. The experiments principally operated within the hydrodynamic lubrication regime for both SKF bearings, while within the mixed lubrication regime for the budget bearing. The Run to Failure tests were then conducted to replicate natural failures in an accelerated yet controlled manner, by reducing the life expectancy of a roller bearing through exceeding the specified operational limits. It was shown that as the damage propagates, the AE signal levels increase. Based upon the 3 types of bearings adopted for the test, maximum AE activities indicating failure emerged into the life span of 66 hours for SKF NU202ECP, 88 hours for SKF NU202ECP/C3 and 22 hours for NU202EM. It is concluded that the data analysis process characteristically showed that the AE RMS signal is a robust technique and capable of perceiving present damage within the rolling element bearing.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	1) Roller bearings with different clearances and qualities 2) Run to Failure tests 3) Acoustic Emission Monitoring 4) RMS 5) Lambda
Date of First Compliant Deposit:	12 March 2024
Last Modified:	08 Apr 2024 15:32
URI:	https://orca.cardiff.ac.uk/id/eprint/167143

Actions (repository staff only)

Edit Item