Abstract: The local mean decomposition (LMD) method presents its own ability for processing nonlinear and non-stationary signals. It can effectively obtain the time-frequency characteristics of non-stationary signals. But there is an involved end effect in the course of local mean decomposition, and the end effect can cause the distortion of decomposition results. Based on the demodulation analysis of vibration signal, a new method for restraining the end effects of local mean decomposition based on the energy operator demodulation of symmetrical differencing. The signal is decomposed into a series of single component signals by the local mean decomposition method, then each single component signal can be demodulated by the method of symmetrical differencing energy operator, and the instantaneous amplitude and instantaneous frequency of each single component signal can be got, the time-frequency distribution of the signal is obtained. To evaluate the effect of endpoint suppression method, an evaluation criterion is defined, compared with the other two endpoint effect suppression methods, the superiority of the proposed method is verified. The results of simulation and practical signal analysis show that the method can restrain the end effects of LMD and implement rotating machinery fault diagnosis effectively.

Key words: symmetrical differencing energy operator;demodulation;local mean decomposition;end effect