Juanjuan Shi to present on the 26th!

Juanjuan Shi will be presenting her PhD work on Tuesday May 26th at 10:00am in CB B012.  She will give a talk on “Morphology-based feature extraction method and resampling-free fault identification technique for bearing condition monitoring”.  Her supervisors are Dr. Ming Liang and Dr. Dan-Sorin Necsulescu.  Abstract of the talk is below.

Date: May 26th, 2015

Time: 10:00am

Location: CBY B012


The effectiveness of vibration-based bearing fault diagnosis is often handicapped by 1) background noise and compounded effects of interferences for constant speed case, and 2) non-stationarity plus the two aforementioned factors for time-varying speed case. To address these issues and overcome the shortcomings of filter-parameter-dependence and error-propagation of conventional methods, novel methods are proposed in this work.
Two morphology-based methods are first proposed to extract fault features without prefiltering for constant speed case. The first method, based on fractal dimension (FD), can suppress interferences and highlight fault-induced impulse envelope by mapping the signal into FD representation. Its effectiveness, however, deteriorates with the interference frequency increase. Hence, the second method, which isolates impulses from interferences and noise via resonance behaviors, is developed. Both methods are independent of frequency information and can reveal fault features without prefiltering.

For bearings under variable speed, since resampling propagates error and complicates the process substantially resampling-free methods are innovatively proposed. A resampling-free order spectrum is derived via the joint application of generalized demodulation and short time Fourier transform, from which not only the existence of faults but also the location of faults can be revealed. Nevertheless, the success of this method relies upon an effective envelope demodulation. Based on the proposed resampling-free order spectrum, a time-frequency analysis technique termed dual demodulation transform is devised and applied to bearing fault identification, without envelope procedure.

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