Complex Demodulation for Bearing Fault Detection
Propulsion technical memo.
AERONAUTICAL RESEARCH LABS MELBOURNE (AUSTRALIA)
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Vibration analysis using the high frequency resonance technique has been used successfully to detect incipient failure in rolling element bearings. This memo outlines a new method of obtaining the demodulated narrow band envelope of a bearing vibration signal from the high frequency resonant response. Previous techniques have used an analogue envelope where the raw analogue signal is bandpass filtered and enveloped before digitising. The method outlined in this document first digitises the vibration signal, performs a complex demodulation operation, then computes the envelope followed by its spectrum. Fault repetition frequencies can be identified in the demodulated spectrum of the high frequency resonant response. Keywords Vibration tests Demodulation Bearing stress Resonant frequency Australia.
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