Vibrations Generated by Rolling Element Bearings having Multiple Local Defects on Races

The vibrations generated by deep groove ball bearings having multiple defects on races have been studied in this paper. The vibrations are analysed in both time and frequency domains. The equations for time delay between two or more successive impulses have been derived and validated with simulated and experimental results. The relationships between amplitudes of frequencies for impulse train, delayed impulse train and combination of two impulse trains have been established. Frequency spectra for single and two defects on either race of deep groove ball bearings are compared. No additional frequencies due to time delay between successive impulses are observed in case of multiple defects. The frequency spectra do not provide any information about number of defects; however this information is found in time domain analysis. (C) 2014 Elsevier Ltd.