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Research On Fiber Protected Technics And Temperature Sensing Properties Of Smart Structure

Posted on:2008-04-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:J F XieFull Text:PDF
GTID:1118360215487772Subject:Materials Processing Engineering
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Recently, fiber Bragg gratings (FBG) have received much attention in the areasof optical Communications and fiber sensors. Fiber Bragg Grating sensors offermany important advantages such as electrically passive operation,big signalbandwidth,high sensitivity and multiplexing capabilities,low weight, smallconfiguration and suitable to be used in the high temperature,corrosive and dangerousenvironment.The fiber bragg grating sensors possess broad application foreground inthe safety scrutiny of especially situation,for example,big architecture and oilwell.Fiber Bragg gratings is the mainly research object in the dissertation. Theprotected technics,basic properties and sensing application of FBG are studied intheory and verified by experiments and simulation.The following are the maincontents:Fiber Bragg grating is protected effectively in the dissertation, a non-coarseningfiber surface electroless plating technics with good adhesion force between layer andfiber is proposed, according to the characters of this project's post-processing, usingplating layer's adhesion force,electric properties,brightness and plating depositionrate as the main judgment of the electroless plating, with the help of orthogonaltesting, the technics for optimal elecroless plating is achieved, optimum conditionsare: NiSO4·6H2O 25g.L-1,NaH2PO2·H2O 20g.L-1,C3H6O2 20mL.L-1,H3BO3 20g.L-1,NaF 1 g.L-1,saccharin 2mg.L-1,pH 4.5,temperature 86℃.The Fiber Bragggrating is electroplated after electroless plating.for the more, theoretical analyses forthe results is applied here.According to the characteristic of nickel-coated FBG sensors, the strains andstresses on the nickel-coated FBG sensors under varied temperature were analyzed.The temperature sensitivity of nickel-coated FBG sensors was deduced in theory andverified by experiment. It was proved that wave shift and strains/stresses ofnickel-coated FBG sensors are proportional to the temperature change. Therelationship between plating thickness and temperature sensitivity was analyzed. AFinite Element Analysis Software (ANSYS) was used to simulate the stresses andstrains on the nickel-coated FBG sensors under varied temperatures. When plating thickness was 4.56um, temperature sensitivity was 14.3235pm/℃in theory andexperiment result was 13.92pm/℃.The results of theoretical analysis matches theones from experiments and simulation well.In order to research the relation between temperature sensitivity and platingthickness of nickel coated fiber bragg grating,the same FBG was electroless platedfour times, plating thicknesses of nickel coated FBG and temperature sensitivitieswere measured after every electroless plating, so the temperature sensitivities ofnickel coated FBG with different plating thickness were athieved. The temperaturesensitivity formula of nickel coated FBG was discussed, the relation betweentemperature sensitivity and plating thickness of nickel coated fiber bragg grating wasanalyzed in theory and verified by experiment。When plating thickness were2.315um, 16.655um,85.255um respectively, temperature sensitivities were12.2403pm/℃,17.3782pm/℃,19.6026pm/℃in theory and experiment results were12.313pm/℃, 17.1pm/℃,20.024pm/℃, The results of theoretical analysis matches theones from experiments well. The hysteresis of wave-shift was discussed andhysteresis disappeared after heat treatmentThe temperature sensitivity of naked and nickel-clad FBG which embedded incement mortar was researched by theory and experiment, the strains and stresses onthe embedded FBG sensors under varied temperature were analyzed. Thetemperature sensitivity formula of embedded FBG was deduced in theory and verifiedby experiments. The strains of FBG which embedded in cement mortar under variedtemperature were analyzed in theory and simulated by ANSYS software. The resultsof theoretical analysis matches the ones from experiments and simulation well.The strains and stresses on the FBG in smart metal structure under variedtemperature were analyzed.The temperature sensitivity of FBG in smart metelstructure was deduced in theory. Take FBG (which protected by Ni-P alloy andembedded in Aluminum-Alloy) as example, the strains of FBG under variedtemperature was analyzed in theory and simulated by Finite Element AnalysisSoftware (ANSYS). The results of theoretical analysis matches the ones fromsimulation well.
Keywords/Search Tags:fiber bragg grating (FBG), FBG protecting, temperature sensitivity, Finite Element Analysis, fiber smart structure
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