Comparison between shock pulse method and vibration analysis methods on early fault detection of rolling element bearing

In this paper, the vibration analysis methods and shock pulse method (SPM) are compared in order to detect the unhealthy condition as well as fault type in the early stages of rolling element bearing (REB) degradation. To analyze vibration signals, three weak signature detection methods based on continuous wavelet transform (CWT), empirical mode decomposition (EMD) and envelope technique are employed. A set of accelerated life tests on REBs was designed and performed in CM lab of Sharif university of technology. Seven tests were conducted and vibration signals, as well as shock pulse signals, were recorded regularly. The trend of vibration level and shock pulse level are compared for early detection of the unhealthy condition in REBs. In addition, the extracted spectrums from SPM, CWT, EMD, and envelope techniques are studied to detect bearing characteristics frequencies (BCFs) to diagnostics. Results show that SPM has better performance on early fault detection of REBs rather than vibration analysis techniques.