Fault Diagnosis of Rolling Bearings Under Variable Speed Conditions Based on Order Analysis

To address the issue of bearing fault diagnosis without speed signal, a phase-ratio analysis method based on speed tracking is proposed. Firstly, the Short-Time Fourier Transform (STFT) is employed to obtain a time-frequency map. Then, the rotation frequency is calculated based on the parameters of the bearings, as well as the speed range. Subsequently, the speed matching tracking method is utilized to track the rotation frequency from the time-frequency map, followed by linear fitting and resampling to approximate the speed signal. Finally, the obtained signal is angularly sampled and subjected to FFT spectral analysis to obtain the order ratio spectrum. Based on the features of the order ratio spectrum, bearing faults are diagnosed.