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- 저자 : Yanyang Zi (검색결과 3 건)
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Zitong Zhou,Jinglong Chen,Yanyang Zi,Tong An 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
Fault identification for bearings of special electromechanical equipment is significant to avoid catastrophic accidents. However, spectral aliasing and nonstationarity resulted from variable speed condition make this task difficult. In this paper, a modified self-organizing maps (SOM) based on nonlinear neural weight updating way is proposed to solve the problem of bearing fault severity identification in variable speed condition. Firstly, a multi-domain features extraction method based on angular re-sampling technique is introduced. Then considering the nonlinear relationship between fault severity and fault features, the traditional Euclidian distance of SOM is substituted with the geodesic distance when update the neural weight and select the best-matching cell, which can improve the nonlinear identification ability of proposed method. Finally, two cases are performed and the results show that the method can identify bearing fault with different severities effectively and have practical significance when considering both accuracy and time cost compared with other methods.
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Modified breathing mechanism model and phase waterfall plot diagnostic method for cracked rotors
Jingsong Xie,Wei Cheng,Yanyang Zi 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6
Transverse breathing cracks are a primary damage mode in rotor systems and seriously influence the safety and reliability of equipment operation. The vibration characteristics exhibited by cracked rotors when passing through critical speeds serve as important evidence in the diagnosis of cracks, and a breathing mechanism model without weight dominance is needed to study these resonant characteristics. In this work, a restoring force modified model is proposed for studying the breathing mechanism of cracked Jeffcott rotors without weight dominance. Furthermore, a novel phase waterfall plot method that can identify frequency components with weak amplitudes is proposed to analyze the vibration response characteristics of cracked Jeffcott rotors. Numerical and experimental studies indicate that the phase waterfall plots effectively recognize the weak characteristic frequencies of cracked rotors. This study can also provide references for the crack monitoring of rotor systems.
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Sifting process of EMD and its application in rolling element bearing fault diagnosis
Hongbo Dong,Keyu Qi,Xuefeng Chen,Yanyang Zi,Zhengjia He,Bing Li 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8
Among the vibration-based fault diagnosis methods for rolling element bearing, the shock pulse method (SPM) combined with the demodulation method is a useful quantitative technique for estimating bearing running state. However, direct demodulation often misestimates the shock value of characteristic defect frequency. To overcome this disadvantage, the vibration signal should be decomposed before demodulation. Empirical mode decomposition (EMD) can be an alternative for preprocess bearing fault signals. However, the trouble with this method’s application is that it is time-consuming. Therefore, a novel method that can improve the sifting process’s efficiency is proposed, in which only one time of cubic spline fitting is required in each sifting process. As a consequence, the time for EMD analysis can be evidently shortened and the decomposition results simultaneously maintained at a high precision. Simulations and experiments verify that the improved EMD method, combined with SPM and demodulation analysis, is efficient and accurate and can be effectively applied in engineering practice.
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