Rolling Bearing Fault Diagnosis by Using a New Index: The Compound Weighted Characteristic Energy Ratio

To improve extraction accuracy of bearing fault feature, a novel index named weighted characteristic energy ratio (WCER) is proposed in this article. In WCER, the fault feature in squared envelope spectrum is enhanced through a square operation, and a series of decreasing weights are imposed on the increasing fault harmonics to highlight the low-order fault feature and suppress the noise around the high-order harmonics. For unknown fault types, including single and compound faults, another index named compound WCER (CWCER) is proposed on the basis of WCER. The optimal resonant frequency band is determined via maximizing WCER and CWCER, and the fault feature can be effectively extracted. WCER is applied to diagnose two single faults, whereas CWCER is employed to detect two single faults and a compound fault. Their superiority to traditional indices is demonstrated; they can be better applied to bearing fault diagnosis, especially for unknown faults.