Papers by Keyword: Vibration Signal Analysis

Abstract: Bispectral analysis is one of the relatively more recent tools in signal processing used for detection and identification of higher harmonics in a signal. It is also acknowledged to be one of Higher Order Spectral Analysis (HOSA) effective tools for detecting nonlinear behavior in mechanical systems. In this study, vibration sources in a hydraulic machine which may have features of nonlinear behavior were investigated. An experimental study was undertaken to formulate a more sensitive and effective method using Bispectral analysis to diagnose cavitation in a centrifugal pump facility. Cavitation was induced on the suction side of the pump. The cavitation signal was analyzed with and without induced cavitation conditions at different locations on the pump, and analyzed using FFT and bispectrum methods. It was observed that bispectral analysis could be used as an early indicator of cavitation with changes for severity of cavitation.

Abstract: As a universal component connection and power transmission gear box, is widely used in the modern industrial equipment, but also an easy failure parts, has a great influence on the running state of the working performance of the whole machine. This paper first analyzes the gear box fault form and characteristics, the gear box fault diagnosis method based on vibration signal analysis, and analysis of the vibration signal processing method for gear vibration signal analysis in time domain, including parameters, resonance demodulation method and cepstrum analysis method. Then using Visual C + + language and data acquisition card for real-time acquisition of gearbox vibration data software, including parameter setting, data acquisition module, signal real-time display module and data storage module. The data acquisition program is developed, the actual acquisition of gearbox vibration data of gear fault and bearing fault, and analyzed.

Abstract: In order to facilitate dynamic analysis of spindle, improve the vibration characteristics of the spindle and achieve the goal of control of spindle motion stability. A spindle vibration testing system is developed with necessary sensor, signal conditioner and data acquisition card based on Labview software in this paper. The spindle vibration testing and analysis system is formed based on virtual instrument graphical programming language Labview. The hardware is reduced in testing process. At the same time, acquisition, processing and analysis for vibration signal are realized, and the costs of hardware are greatly reduced. The testing work is made more convenient and quick by this system, and test is made more intuitive by its real-time display function. It will provide a scientific basis for searching for measures to reduce the spindle vibration and developing a new generation of mechanical structure of the spindle.

Abstract: Aiming at the safe operation of the wind turbine, a feature extraction method of vibration signal based on the principle of blind source separation was proposed. Blind source and the current state of fault signal was separated and predicated by Using historical data of wind turbine vibration signal as the observation noise, and then fault diagnosis signal mechanical operation was analyzed, the HMM/SVM series fault diagnosis models structure was proposed. By calculating the matching degree of unknown signal and wind power equipment in the state using HMM, the features for SVM was formed to achieve the finally discriminant. The experimental results showed that the fault diagnosis method can precisely and effectively complete the wind power equipment, higher than pure HMM or SVM diagnostic accuracy.

Abstract: The different clearances of main bearing of previously designed on EQ6100 model gasoline engine is diagnosed by means of vibration monitoring mechanism. Breakdown signals of main test on different speed, clearance of main bearing, test spot and weather were analyzed by Spectral Analysis method and compared with normal and abnormal vibration signals. As a result, the characteristic parameters and the identifying methods of breakdown are given. In addition, the problems of fault detection are pointed out.

Abstract: In order to extract effectively detection signals in the noise background for non-stationary signal.On the basis of EEMD, improved EEMD is put forward, the improve EEMD threshold noise reduction is researched in this paper.The simulation signal compared the noise reduction effect of the wavelet,EMD,EEMD,and the improved EEMD. The improved EEMD threshold noise reduction have the best noise reduction result , the highest signal-to-noise ratio, the smallest standard deviation error.After the improved EEMD threshold noise reduction , the measurement signal time domain waveform smooth. More high frequency noise was obviously reduced in Hilbert time- frequency spectrum. Signal-to-noise ratio significantly improve, and signal characteristics are very clear.

Abstract: In order to correct the endpoint effect and modal aliasing phenomenon in EMD and EEMD, improved EEMD is put forward in this paper. on the basis of the cause of the endpoint effect,the improvement measures are proposed. The pulse interference and noise pollution is suppressed by threshold noise reduction.The overshoot and undershoot phenomenon is controlled by improving 3-spline interpolation to fit envelope. The endpoint effects is lessened by signal SVM prolongation.Compared with EMD and EEMD, not only the IMF false component is reduced, the modal aliasing avoided, and effectively the endpoint effect restrained, the distortion problem in the signal decomposition produces corrected in the results of simulation signal and the measured signal by the improved EEMD in this paper.

Abstract: It is often needed in engineering that detecting and analyzing vibration signal of some equipment. To meet the requirement, a portable detecting and analytic instrument was designed using virtual instrument concept. In the instrument, notebook computer was used as the platform of hardware. Vibration signal was obtained by integrated piezoelectric acceleration sensor (DTS0104T), and was transferred to a notebook computer through data acquisition card (NI USB-6210) based on USB bus. The software, running on the notebook computer, was developed under LabVIEW. Vibration signal could be displayed on screen, recorded in disk or printed by printer, retrieved, and analyzed. The analysis functions of the instrument include: time-domain analysis, frequency-domain analysis, time-frequency domain analysis, and correlation analysis. The instrument is compact, portable, powerful, and with friendly interfaces, has broad application prospects.

Abstract: Fault diagnosis is an important technical method to improve the safety index and economic effectiveness of wind turbines, it also provide support to advanced maintenance and design in wind power equipment. In this paper, we have done vibration testing on two wind turbines, one is in normal, the other is with faulty, and then carried on comparative analysis of vibration signal to the experimental data, finally designed a fault diagnosis method for direct-driven wind turbine generators.

Abstract: A method of vibration analysis for mechanical fault detection based on adaptive noise canceling(ANC) and envelope analysis was presented. The adaptive filtering was used for noise canceling and feature extraction from vibration signal measured for the detection. The envelope analysis based on analytic wavelet was also used for the fault detection. Experiment shows that the method proposed in this paper is very effective for reducing noise, and for vibration analysis to discriminating the fault types with a high accuracy.