Order Bi-spectrum For Bearing Fault Monitoring and Diagnosis Under Run-up Condition

Varying speed machinery condition detection and fault diagnosis are more difficult due to non-stationary machine dynamics and vibration. Therefore, most conventional signal processing methods based on time invariant carried out in constant time interval are frequently unable to provide meaningful results. This paper deals with the detection of bearing faults in gearbox under non-stationary run-up of gear drives. In order to process the non-stationary vibration signals such as run-up or rundown vibration signals effectively, the order bi-spectrum technique is presented. This new method combines computed order tracking technique with bi-spectrum analysis. First, the vibration signal is sampled at constant time increments during run-up of gearbox and then uses numerical techniques to resample the data at constant angle increments. Therefore, the vibration signals are transformed from the time domain transient signal to angle domain stationary one. Second, the re-sample signal is processed by bi-spectrum analysis method. The procedure is illustrated with the experimental vibration data of a gearbox. The experimental results show that order bi-spectrum technique can effectively diagnosis and diagnosis the faults of bearing.