In this paper we present the comparison results of induction motor fault detection using stator current, vibration, and acoustic methods. A broken rotor bar fault and a combination of bearing faults (inner race, outer race, and rolling element faults) were induced into variable speed three-phase induction motors. Both healthy and faulty signatures were acquired under different speed and load conditions. To address the detection capabilities of the above methods, comparisons are made in both the time and joint time-frequency domains. In the frequency domain, spectral differences are compared and characterized under constant speed conditions. To evaluate the detection sensitivities under non-stationary conditions (e.g. startup), a joint time-frequency method called the smoothed pseudo Wigner-Ville distribution (SPWVD) is employed to analyze non-stationary signatures. The SPWVD is a powerful technique for revealing non-stationary characteristics of motor signatures. Experimental results show that the stator ...

Detection of Induction Motor Faults: A Comparison of Stator Current, Vibration and Acoustic Methods

http://www.crbnet.it/File/Pubblicazioni/pdf/1430.pdf

Diagnosis of internal combustion engine through vibration and acoustic pressure non-intrusive measurements

Combustion Characterization in Diesel Engine via Block Vibration Analysis

As one of the most common gear failure modes, tooth wear can produce nonlinear modulation sidebands in the vibration frequency spectrum. However, limited research has been reported in monitoring the gear wear based on vibration due to the lack of tools which can effectively extract the small sidebands. In order to accurately monitor gear wear progression in a timely fashion, this paper presents a gear wear condition monitoring approach based on vibration signal analysis using the modulation signal bispectrum-based sideband estimator (MSB-SE) method. The vibration signals are collected using a run-to-failure test of gearbox under an accelerated test process. MSB analysis was performed on the vibration signals to extract the sideband information. Using a combination of the peak value of MSB-SE and the coherence of MSB-SE, the overall information of gear transmission system can be obtained. Based on the amplitude of MSB-SE peaks, a dimensionless indicator is proposed to assess the effects of gear tooth wear. The results demonstrated that the proposed indicator can be used to accurately and reliably monitor gear tooth wear and evaluate the wear severity.

/pdf/gear-wear-process-monitoring-using-a-sideband-estimator-2zweb20o9f.pdf

Gear wear process monitoring using a sideband estimator based on modulation signal bispectrum

Diesel Engine Combustion Monitoring through Block Vibration Signal Analysis

In this, Part 1 of the paper, the sound generation of a diesel engine is modelled based upon the combustion process, and time-frequency analysis is used to reveal the underlying characteristics of the sound waves. Simulation shows that the frequency bandwidth of the generated acoustic signals is significantly widened around the engine''s top dead center (TDC) positions, with the energy concentrated predominantly at the firing frequency and its harmonics. As anticipated, the model predicts an increase in sound level with increasing engine load and speed, and the model-predicted noise generation is correlated with waveforms extracted from intrusively-monitored cylinder pressure.

Real monitored data, taken in an ordinary engine test-bay environment and without special acoustic monitoring precautions, is shown to be highly contaminated due to adverse environmental acoustics and intrusive background noise. The representation of acoustic signals using the smoothed pseudo-Wigner- Ville distribution (SPWVD) and continuous wavelet transform (CWT), however, is found to permit recognition of the adverse influences of the measurement environment. This subsequently allows the monitored sound characteristics to be closely correlated to the combustion process. Part 1 concludes with an investigation of the influences of the measurement environment upon the acoustic data, and of the signal conditioning and representation techniques required to reveal the condition-indicating content of the monitored acoustic data.

The sister paper to this (""Part 2 - Fault Detection and Diagnosis""), puts the developed methodology to the test by investigating its capability to detect and distinguish between a range of realistic yet incipient engine faults on a standard production engine in an uncontrolled industrial environment.

The Condition Monitoring of Diesel Engines Using Acoustic Measurements-Part 1: Acoustic Characteristics of the Engine and Representation of the Acoustic Signals

A. Y. T. Leung

Papers

The Condition Monitoring of Diesel Engines Using Acoustic Measurements-Part 1: Acoustic Characteristics of the Engine and Representation of the Acoustic Signals