Research On Sensing Theory And Method Of Dual-parameter Fiber Sensor

Fiber Bragg grating(FBG)sensor has been used for measuring various physical and chemical parameters due to the unique advantages.In this paper,to meet the demands of temperature,strain and corrosion ratio monitoring in engineering field,a research about the package method and sensing characteristics of FBG sensors is carried out.The response times of temperature sensors with different packages are measured.A dual-parameter sensor based on hybrid FBG and Fabry–Perot(FP)configuration for simultaneous measurement of strain and temperature is proposed to realize temperature compensation.The spectrum-profile-indentification technique based on correlation demodulation is proposed to increase sensor quantity of wavelength division multiplexing(WDM).The electrochemisty corrosion mechanism of rebar is investigated and the dual-parameter sensor based on FBG for simultaneous measurement of corrosion and temperature is designed.The major work of the thesis is as follows:1.The no-glue package method and the response time of FBG temperature sensor are studied.The no-glue package methods of FBG temperature and strain sensor are explored.Moreover,the response characristics of FBG sensors using these package methods are measured.The heat transfer model and the response time of three types of packaged FBG temperature sesors in the steady-state temperature and water medium are discussed in detail.2.A fiber-optic dual-parameer sensor based on hybrid FP and FBG configuration for simultaneous measurement of strain and temperature is proposed.The theoretical model and demodulation matrix of strain and temperature dual-parameer sensing are constructed.The FP cavity is fabricated using the fiber fusion splicer.The strain and temperature is simultaneously measured according to different strain and temperature sensitivity coefficents3.The spectrum-profile-indentification technique is discussed.Based on WDM,according to the different spectrum profiles of FBG and TFBG,the spectra are identified using correlation technique and the same time the wavelengths are demodulated.On the premise of remaining the advatages of WDM system,this method can develop the multiplexing abilities.4.The electrochemisty corrosion mechanism and a dual-parameter FBG sensor for simultaneous measurement of corrosion of rebar and temperature are investigated.According to volume expansion principle,FBG corrosion sensor through simultaneous measurement of strain and temperature is proposed.The strain transmission constructure are designed.The volume expansion causing by the corroded tested rebar is converted to the axis strain of FBG.The simultaneous measurement of corrosion and temperature is realized by means of the acceleration corrosion experiment.The volumn and mass corrosion ratio of the tested rebar are determined according to the wavelength change of the two FBGs.