การศึกษาความสัมพันธ์ระหว่างสัญญาณการสั่นสะเทือนและรอยแตกร้าวบนเฟือง / สุรศักดิ์ คกมิ = A study of the relationship between vibration signal and gear crack / Surasak Kokmi
This research dealt with gear crack diagnosis based on vibration signal analysis. The relationship of vibration signal and crack length was analyzed by means of time domain, spectral and cepstral analysis. Vibration signal was recorded by using spectrum averaging, zoom processing, and synchronous time averaging techniques. One cracked tooth was prepared on brass pinions in several lengths by using a dynamic servo fatigue testing machine. Cracked pinions were tested at various speeds and applied loads on an experimental test rig. The study of time domain signal and crack length shows that the magnitude of Kurtosis and Crest Factor increases with crack evolution while the RMS value does not change with crack length. The tooth meshing period can be clearly seen in the synchronous time averaging signal. The cracked tooth and shock pulse around cracked tooth meshing period can be identified in the direction of tooth contact. It is found from the spectral analysis that the changing of the amplitude at 1xGMF do not directly relate to crack length. Number of lower sidebands of the pinion speed around 1xGMF increase with crack length. Harmonics of pinion speed sideband which resemble with any natural frequencies of test bed greatly increase with crack length. In case of cepstral analysis, gamnitude of 1/P increases with crack length until the crack length reaches 2.5 mm and then it slightly decreases. The zoom processing of the signal enhances the separation of each harmonics of sideband. The values of the rate of cepstral gamnitude obtained from this method change greater than the signal from other methods.
