Extraction of transmission bearing fault characters based on EMD and fractal theory

The vibration signal of transmission bearing is decomposed by empirical mode decomposition, and fractal dimensions of decomposed intrinsic mode functions are calculated to extract fault characters of transmission bearings of different conditions. The results show that empirical mode decomposition method is able to separate signals of different frequency bands effectively, and the fractal dimension of specific IMF component is able to reflect the technology state of transmission bearing sensitively, which can be selected as the characteristic parameters to diagnose transmission bearing fault. The combination of empirical mode decomposition and fractal dimension is an effective method of transmission bearing´s fault character extraction.