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Research Papers

# Defect Diagnosis for Rolling Element Bearings Using Acoustic Emission

[+] Author and Article Information
Yongyong He

State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, P.R.Chinaheyy@mail.tsinghua.edu.cn

Xinming Zhang

State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, P.R.China

Michael I. Friswell

School of Engineering, Swansea University, Swansea SA2 8PP, UK

J. Vib. Acoust 131(6), 061012 (Nov 20, 2009) (10 pages) doi:10.1115/1.4000480 History: Received November 18, 2008; Revised August 29, 2009; Published November 20, 2009; Online November 20, 2009

## Abstract

Rolling element bearings are very common components in rotating machinery. Hence, condition monitoring and the detection of defects are very important for the normal and safe running of these machines. Vibration based techniques are well established for the condition monitoring of rolling element bearings, although they are not so effective in detecting incipient defects in the bearing. Acoustic emission (AE) is receiving increasing attention as a complementary method for condition monitoring of bearings as AE is very sensitive to incipient defects. This paper presents an experimental study to investigate the AE characteristics of bearing defect and validates the relationship between various AE parameters and the operational condition of rolling element bearings. To analyze the characteristic vibration frequency of the bearing using the AE signal, short-time rms and autocorrelation functions are integrated to extract the actual characteristic frequency. The AE signal is then analyzed using standard parameters of the signals to explore the source characteristics and sensitivity of typical rolling element bearing faults. The results demonstrate that the proposed method is very effective to extract the actual characteristic frequency of the bearing by AE signal. Furthermore the AE parameters are always sensitive to the running and fault conditions, which have a strong influence on the strain and deformation within the bearing material.

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## Figures

Figure 1

The sketch of the experimental test rig

Figure 2

The experimental test rig

Figure 3

AE data acquisition system

Figure 4

Test bearing and location of AE sensors

Figure 5

AE signals with defect on the outer race from sensor 1: (a) condition (L0, S1, D1), (b) condition (L1, S1, D1), (c) condition (L2, S1, D1), (d) condition (L0, S2, D1), (e) condition (L1, S2, D1), and (f) condition (L2, S2, D1)

Figure 6

The spectrum of the AE signal under condition (L1, S1, D1)

Figure 7

STRMS and autocorrelation analysis of the AE signal for condition (L1, S1, D1) from sensor 1: (a) STRMS and (b) autocorrelation function

Figure 8

AE signals with defect on the outer race from sensor 2: (a) condition (L0, S1, D1), (b) condition (L1, S1, D1), (c) condition (L2, S1, D1), (d) condition (L0, S2, D1), (e) condition (L1, S2, D1), and (f) condition (L2, S2, D1)

Figure 9

STRMS and autocorrelation analysis of the AE signal for condition (L0, S1, D1) from sensor 2: (a) STRMS and (b) autocorrelation function

Figure 10

STRMS and autocorrelation analysis of the AE signal for condition (L2, S1, D1) from sensor 2(a) STRMS and (b) autocorrelation function

Figure 11

AE signals with defect on the inner race from sensor 1: (a) condition (L0, S1, D1), (b) condition (L1, S1, D1), (c) condition (L2, S1, D1), (d) condition (L0, S2, D1), (e) condition (L1, S2, D1), and (f) condition (L2, S2, D1)

Figure 12

Characteristic frequency analysis for condition (L2, S2, D1) from sensor 1: (a) STRMS, (b) autocorrelation function, and (c) spectrum of autocorrelation function

Figure 13

Characteristic frequency analysis for condition (L2, S2, D1) after demodulation: (a) STRMS, (b) autocorrelation function, and (c) spectrum of autocorrelation function

Figure 14

Definition of AE parameters

Figure 15

Comparison of AE counts for various conditions

Figure 16

Comparison of amplitude for various conditions

Figure 17

Comparison of rms for various conditions

Figure 18

Comparison of kurtosis for various conditions

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