| In the modern industrial production and manufacturing,rotating machinery is the most widely used in all kinds of mechanical equipment of machinery,such as motor,centrifugal fan,water pump and a variety of machine tools.Its key components like driving shaft system often happen torque and speed fluctuation turbulence due to machinery,power and load transient or persistent,so that the axis of rotation occurs torsional vibration.Torsional vibration stress can make the each end face of the shafting receive alternating shear stress,causing the fatigue accumulation of the shafting,to shorten their working life,seriously even lead to parts of instantaneous destruction.Therefore,it is necessary to use some effective monitoring analysis techniques to solve the problems and avoid possible catastrophic accidents.Monitoring analysis technology of the torsional vibration is mainly manifested in two aspects: the one is to obtain the torsional vibration signal,the two is to analyze the signal.In the past,people adopted the traditional electrical sensor technology and laser detecting technology to obtain the signal,but these detection techniques always exist vulnerable to electromagnetic interference,difficulty to install,and costly;people use the traditional time domain analysis,FFT and wavelet to analyze the torsional vibration signal,but these signal analysis techniques always exist the difficulty to extract the changed continuously and weak signal.The purpose of this study is to overcome the traditional testing technology and the shortage of the signal analysis technology,realize the accurate monitoring and analysis of torsion vibration signal in different working conditions,a new method that combines the new type of FBG detection with the EMD analysis method of processing unsteady nonlinear signal is put forward.The main work of the paper includes the following aspects:1.Through the analysis of the axis of torsional vibration measurement technology,signal analysis method and the research status of FBG sensing technology,we put forward a new method that we combined the inspection of new type of FBG with the EMD to detect characteristics of torsional vibration signal.2.By studying the mechanism of rotating machinery shafting torsional vibration and the FBG sensing technology,we designed a fiber grating sensor of the torsional vibration,and then established a strain transfer model between the torsional vibration and fiber Bragg grating;we obtained the sensor characteristics of the sensor by using the finite element simulation analysis of ANSYS workbench,structured the characteristic test system of the FBG sensor of the torsional vibration,realized research on the natural frequency,non-work state and rotating dynamic characteristics,analyzed its sensing properties.3.Through researching the principles and characteristics of the EMD transformation,we researched the congruent relationship between the intrinsic mode function by EMD decomposition and the characteristic frequency of torsional vibration,simulated the actuating motor torsional vibration signal in two states of the process of start and steady work by MATLAB,extracted the characteristic frequency by using FFT,wavelet and EMD;Finally,we combined the simulation of torsional vibration signal with the signal in practical engineering,designed the signal collection and analysis system based on LabVIEW and MATLAB.4.Based on the experiment platform for large rotating machinery tests,we built a detection system for rotating shaft torsional vibration based on the FBG torsional sensor,torque sensor and fiber optic speed pulse sensor;contrastive analysis the torsional vibration signal collected by three sensor systems from time domain to frequency domain;changing operating condition of the rotating shaft,we researched the torsional vibration feature extraction based on EMD and FBG sensing by inflicting the driving signals of single,variable frequency and the main shaft system torsional vibration caused by unbalance of gravity. |
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