Xu Yonggang1£¬He Zhengjia2£¬Wang Taiyong1
(1.School of Mechanical Engineering,Tianjin University,Tianjin 300072, China;2.School of Mechanical Engineering,Xi'an Jiaotong University,Xi'an ¡¡710049,China)
Abstract:A new envelope demodulation method based on empirical mode decomposition (EMD) is proposed to make up the limitation that meaningless frequencies often arise in the envelope spectrum of conventional envelope demodulation method.The vibration signal is decomposed into several intrinsic mode functions £¨IMFs£©by EMD,and the fault information is extracted from the IMFs containing modulated signals£¬which then is effectively separated by EMD,thereby the signal to noise ratio £¨SNR£©of diagnosis signal is improved obviously£®With the aid of the proposed method,vibration signal of one gear-box bearing bridge is decomposed by EMD,and the modulated frequency corresponding to the rotating frequency of high speed axis is demodulated to affirm the fault due to the misalignment of two gear axes. A proper maintenance removes the fault thoroughly,which verifies the validity of this method£®
Keywords:empirical mode decomposition;intrinsic mode function;envelope demodulation;fault diagnosis