An Approach of Bearing Fault Detection and Diagnosis at Varying Rotating Speed

Frequency domain method including high frequency resonance technique (envelope analysis) is one of the most efficient methods for detecting localized defect of rolling element bearings. But this theory has a limitation that bearings must run at a constant rotating speed. However, in practice, with load change or in the run-ups and run-downs processes, bearings often work at varying rotating speed. This paper proposes a new scheme to solve this problem, which is based on time-frequency analysis and order analysis techniques. For realizing order tracking without the employment of hardware such as tachometer and keyphasor, the instantaneous frequency estimation method is used for accessing the resampling time serials. The feasibility of this scheme is confirmed by experiment on bearings with outer and inner race faults.