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Design And Implementation Of Fiber Bragg Grating Vibration Sensing System

Posted on:2019-06-09Degree:MasterType:Thesis
Country:ChinaCandidate:W M YangFull Text:PDF
GTID:2428330545488368Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
In many practical engineering applications,it is very important and necessary to measure a variety of low frequency/high frequency vibration measurements.Fiber grating with its miniature size,high anti-electromagnetic interference,high sensitivity,high real-time performance,low insertion loss,high reusability,is widely used in bridge structure health monitoring,earthquake monitoring,oil exploration and building damage detection in engineering practice.A new method of fiber Bragg grating vibration sensing system based on various structures is explored to meet the demand of vibration signal with easy demodulation,high sensitivity,good stability and low cost.It is still a hot topic at home and abroad.At present,the FBG sensor is used as the main fiber grating vibration sensor with wavelength demodulation basically.The wavelength demodulation cost is relatively high,and the demodulation system is complex.As a newly emerging fiber grating sensor,Ex-TFG has many advantages over FBG,especially in vibration sensing,there are less reports about it at home and abroad.Based on the above problems,the principle of FBG and Ex-TFG is studied in this paper.The basic model of vibration sensor is designed,and the model is simulated by ANSYS tool,and the sensor is made.Finally,the vibration sensing system is set up to measure the low-frequency vibration signal produced by the piezoelectric ceramics.The main contents include:?1?Combined with the finite element method and the ANSYS simulation tool,the designed cantilever beam fiber Bragg grating vibration sensor is simulated.The simulation results show that the average error of the theoretical calculation and simulation of cantilever stiffness value is 1.98%,the average error of the simulation and the theoretical calculation of natural frequency value is 3.068%.?2?The FBG vibration sensing experiment is carried out.The experimental results show that the average error between the natural frequency of the theoretical calculations and experimental results is only 2.87%.Vibration sensor with 0.3mm thickness has better performance,flat response range of 10Hz-60Hz,the acceleration sensitivity is 51.25pm/(m·s-2),the maximum acceleration sensitivity is 416.81 pm/(m·s-2).When the vibration frequency is the same,the linear correlation between the wavelength shift amplitude and the vibration amplitude is 0.998.The main frequency component of the sensing signal is over 80%after the FFT transformation.?3?In this paper,an experimental system for vibration sensing of a cantilever beam with equal strength based on Ex-TFG is designed,and the related experiments are carried out.The experimental results show that when the thickness of the iso-intensity cantilever beam is 0.3mm,Ex-TFG has the best performance in TE polarization.The flat response range of the sensor is 10Hz-250Hz,the resonant frequency is about 67Hz,and the sensitivity is 26.16mv/(m·s-2),the maximum acceleration sensitivity up to 81.065mv/(m·s-2).The linear response of output signal and vibration signal is 0.996.The FFT transform main frequency component of the sensing signal accounted for more than 80%.?4?A vibration sensing experimental system of gantry frame based on Ex-TFG is designed,and relevant experiments are carried out.The experimental results show that the response time of the designed sensor system is 0.045s,and the average error of the frequency response in the detection range of 1-10 Hz is 0.085Hz,the maximum relative error rate is 1.4%,and the magnitude response linearity of 1-5V is 0.965.
Keywords/Search Tags:Fiber Bragg Grating, Excessively tilted fiber Bragg grating, Low frequency vibration, Finite element method, Equal strength cantilever beam
PDF Full Text Request
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