Measurement And Analysis Of Vibration And Noise Signals Of Rotating Machines By Non-Invasive Method

Traditional vibration detecting methods for rotating machines with chambers are of 'inner detecting' method, which installs transducers inside the machine chambers. But this method is heavily confined to maneuverability, safety and massive operations when applied to large scale. Contrary to the traditional methods, "outer detection" method (or non-invasive method) has its advantages. This method uses a certain non-invasive detecting method to measure the vibration and the noise of a machine, thus to obtain information as much as it can without any breakage and modification to the structure.The work described in this paper is aimed at the development of an outer detecting and analyzing system. The system uses a piezoelectric sensor as the detector, a sound card of PC as an A/D converter, a software analyzing system. It has a number of new characteristics: full functions on real-time data processing and recording; automatic fault detection and alert; multi-spectrum extended analysis functions. These mean a simpler detection method, no breakage on machine chambers, high mobility.Some faults examining experiments are completed. Especially the research is done on rotor rubbing, bearing friction and unusual multi-harmonic. Detecting methods of these faults are developed, such as fractal geometry, weight center of frequency, peak tracing and peak searching, etc. Based on the experiments, these detecting and analyzing methods have shown to be of practical use. Other features of the system include less CPU time, very suitable for real-time examinations.It is concluded that even there are many difficulties in rotating machines non-invasive method, we can still obtain some useful results.