*Article* **A Fault Feature Extraction Method Based on LMD and Wavelet Packet Denoising**

**Jingzong Yang 1 and Chengjiang Zhou 2,\***


**\*** Correspondence: chengjiangzhou@foxmail.com

**Abstract:** Aiming at the problem of fault feature extraction of a diaphragm pump check valve, a fault feature extraction method based on local mean decomposition (LMD) and wavelet packet transform is proposed. Firstly, the collected vibration signal was decomposed by LMD. After several amplitude modulation (AM) and frequency modulation (FM) components were obtained, the effective components were selected according to the Kullback-Leible (K-L) divergence of all component signals for reconstruction. Then, wavelet packet transform was used to denoise the reconstructed signal. Finally, the characteristics of the fault signal were extracted by Hilbert envelope spectrum analysis. Through experimental analysis, the results show that compared with other traditional methods, the proposed method can effectively overcome the phenomenon of mode aliasing and extract the fault characteristics of a check valve more effectively. Experiments show that this method is feasible in the fault diagnosis of check valve.

**Keywords:** checkvalve; local mean decomposition; wavelet packet transform; K-L divergence
