Effectiveness and Sensitivity of Vibration Processing Techniques for Local Fault Detection in Gears

This paper deals with gear condition monitoring based on vibration analysis techniques.The detection and diagnostic capability of some of the most effective techniques arediscussed and compared on the basis of experimental results, concerning a gear pair affectedby a fatigue crack. In particular, the results of new approaches based on time-frequency andcyclostationarity analysis are compared against those obtained by means of the well-acceptedcepstrum analysis and time-synchronous average analysis. Moreover, the sensitivityto fault severity is assessed by considering two different depths of the crack. The effect oftransducer location and processing options are also shown. In the case of the experimentalresults considered in this paper, the power cepstrum is practically insensitive to the crackevolution. Conversely, the spectral correlation density function is able to monitor the faultdevelopment and does not seem to be significantly influenced by the transducer position.Analysis techniques of the time-synchronous average, such as the ‘residual’ signal and thedemodulation technique, are able to localise the damaged tooth; however, the sensitivity ofthe demodulation technique is strongly dependent on the proper choice of the filtering bandand affected by the transducer location. The wavelet transform seems to be a good tool forcrack detection; it is particularly effective if the residual part of the time-synchronousaveraged signal is processed.