Diagnosis of Rolling Bearing Defects by Envelope Spectrum Analysis of Vibration and Acoustic Signals

The envelope spectral analysis of the high-frequency components of the vibration signal is used to identify defects and assess the condition of rolling bearings. A drawback of this approach is the substantial attenuation of useful signal as the vibration transducer is moved away from the inspected object. This paper presents results of diagnosing rolling bearing defects using envelope spectrum analysis of acoustic pressure signals obtained with measurement microphones. We analyzed the vibration and acoustic emission of a healthy support bearing and of a bearing with a defect artificially introduced on the raceway of its inner ring. It is shown that identification of rolling bearing defects from acoustic pressure signals has limitations related to the fact that sound reflections, background noise, and interference can mask useful signals. The presence of random spatial noise leads to a low signal-to-noise ratio; however, microphones positioned close to the damaged bearing make it possible to detect the presence and type of defect. The results obtained can be used to improve diagnostic techniques and the condition monitoring of rolling bearings.