Mechanism and Method for Outer Raceway Defect Localization of Ball Bearings

The localization of outer raceway defect plays a significant role in malfunction elimination, failure cause analysis as well as the residual life prediction of ball bearings. Based on the nonlinear dynamic model for a ball bearing and the outer raceway defect model considering the ball finite size, this article employs the detailed mathematical derivation and theoretical analysis of the load distribution for the bearing system with an outer raceway defect located at the different angular positions. Therefore, the essential mechanism of the approximate linear relationship between the proposed indices, namely horizontal-vertical synchronized Peak (HVSPeak) and horizontal-vertical synchronized RMS (HVSRMS), and the defect angular position is explained. More importantly, it is theoretically demonstrated that HVSRMS is approximately a cotangent function with the defect angular position as the only variable, which indicates that the index has excellent anti-interference and practicability. In addition, the superiority and necessity of the HVSRMS index can be seen when compared to HVSPeak, RMS, SampEn and Lemple-Ziv. It is validated through simulation and experiment results that HVSRMS index can efficiently diagnose the angular position of outer raceway defect. Finally, the signal denoising methods for HVSRMS are compared and studied, which indicates the direction for subsequent research.