Vibration Analysis Methods in Bearing Damage Detection

Abstract

The goal of vibration analysis is to extract features from the measurements x(t) or x(kT 0 ), T 0 sampling time, to be used for fault detection and diagnosis. The corresponding analysis methods operate in the time domain (autocorrelation functions, power cepstrum, crest and kurtosis factors), in the frequency domain (Fast Fourier Transform FFT, maximum entropy spectral estimation, envelope analysis) and recently in the time-frequency domain. Time-frequency analysis methods represent efficient alternatives to detect bearings damage due to non-stationary impact signals. In this case, the short-time Fourier transform (STFT) or the Wavelet transform are applied. The paper presents a comparative study of some methods used in bearing faults detection (the envelope spectrum and the wavelet transform). A monitoring tool acquires experimental data from a bearing vibration control test rig. An accelerometer captures the signal from the bearing outer ring then it is processed using PCI-4451 National Instruments data acquisition board and LabVIEW soft.

Comparison of envelope demodulation methods in the analysis of rolling bearing damage

“…Even in the case of disturbed signals or very weak shock pulses, the repetition frequency of the shock pulses can be detected in the frequency spectrum of the envelope. (Bujoreanu et al, 2013;Geropp 1995) An RMS value is defined as the square root of the mean square value of a signal. The RMS of the measured signal is commonly used to measure vibration intensity and to indicate an upcoming defect.…”

“…Thus, by determining the frequency of damage, it is possible to determine the location of the damage. (Bujoreanu et al, 2013) According to Isermann (2006), linear overlapping of additional machine vibrations results in several sideband frequencies. This in turn results in more complex frequency spectra and makes it difficult to isolate and diagnose the bearing faults, since the damaging pulse frequencies only appear as sidebands in the frequency spectrum.…”

“…Thus, by determining the frequency of damage, it is possible to determine the location of the damage. (Bujoreanu et al, 2013)…”

“…Even in the case of disturbed signals or very weak shock pulses, the repetition frequency of the shock pulses can be detected in the frequency spectrum of the envelope. (Bujoreanu et al, 2013; Geropp 1995)…”

Rolling Element Bearing Fault Diagnosis Based on Multiscale General Fractal Features

“…The vibration signals generated by faults in bearings have been widely studied. Many studies have developed sound theoretical bases and approaches to diagnose bearing failure [1][2][3]. Much research focuses on obtaining fault information through time and frequency domain signal processing techniques.…”