Application of VMD in Fault Diagnosis for Rolling Bearing under Variable Speed Conditions

Abstract

Two strategies, namely, computed order tracking-variational mode decomposition (COT-VMD) and VMD filtering-envelope order, are proposed and applied respectively to the fault diagnosis of rolling bearings under variable speed conditions. In the COT-VMD strategy, time domain signal was transformed into angle domain by the computed order tracking technology, and then the stationary signal in the angle domain was conducted with VMD, based on which the order spectrum of each mode were obtained. In the VMD filtering-envelope order strategy, however, a time domain envelope of filtered signal by VMD was resampled, after that the envelope order spectrum can be gotten through FFT. The results of fault diagnosis for rolling bearings under variable speed conditions show that both of the two proposed strategies can achieve typical fault diagnosis for rolling bearing, expanding the application of VMD in fault diagnosis under variable speed conditions.