A novel tacholess order analysis method for bearings operating under time-varying speed conditions

Order tracking (OT) of vibration envelope signal based on instantaneous frequency (IF) estimated from a timefrequency representation (TFR) is generally applied to detect bearing defects under time-varying speed conditions. However, these TFR based OT approaches require a high resolution for accurate estimation of the IF. To overcome these issues, a tacholess OT technique based on the fast dynamic time warping (FDTW) algorithm is applied to detect bearing defects for the first time in this paper. FDTW based signal transformation is initially applied to align a filtered shaft signal to a reference signal of constant frequency, followed by reconstructing the bearing envelope signal. The resulting envelope signal is able to provide a richer fault indication than the original signal. The efficacy of the developed OT method is established using a simulation analysis followed by experimental validation using measurements obtained from a laboratory test-rig and a wind turbine bearing.

Automated summary

A new tacholess order tracking technique based on the FDTW algorithm is proposed in this paper for detecting bearing defects. By aligning and reconstructing the shaft envelope signal, a richer fault indication is provided for defect detection.