Shape Perception And Active Monitoring For Smart Structure Using FBG Sensor Array

With the deevelopment oof aeronauticcs and astronaautics, especially the devvelopment off highperffoormance airrcraft, moreand more aatttention hasbeen focuseed on safetyy monitoringg andreliaability observvation for airccraft structurees. As most hhigh performmance aircrafftts use lots off lightmateerials, disturbbance factorss such as airfflow disturbaances, shock wwaves and hheat barriers ccouldcausse strong deeformation aand vibrationn. To pursuee better pneeumatic layoout, aircraftbodybecoomes longerand narroweer, airfoil beccomes more aand more thiin, which maakes aircraftbodyandairfoil structuure more flexxible and elaastic. It couldd increase defformation off the aircraft uunderhighh speed flowfield and thee action of thhrust vectorss As all thesee situations mmay cause seeriousprobblems, aircraaft structure mmonitoring bbecomes a vvery importannt technical iissue, in whhich amosst important ppart is structtural shape aand vibrationn monitoring,, which playy a crucial roole insafegguarding thee safety reliaability, stabillity and survvivability forr high perfoormance airccrafts.Currrently, a reseearch hotspott in high perfformance airrcraft structurral monitorinng is based on theconccept of smartt structures. AAn importantt research dirrection is usinng distributedd embedded FFiberBraggg Grating(FBG) senssors to connstruct smartt surface strructures torealize real--timerecoonstruction ffoor flexiblestructure defformation annd low freqquency vibraation shapewithdynaamic visualizzation techniques, whichhas importannt scientific vvalue, innovaation significcanceandapplication pprospect in mmany areas, noot limited jusst for aerospace field.Based on thhe backgrounnd of a majorr project of thhe National NNatural Sciennce Foundatioon ofChinna, this disseertation takess a simulatedd near spacevehicle moddel as the ressearch object. Bydiscrretely distribbuting embeddded FBG ssensor netwoork into framme structure aand wing suurfacestruccture, deformmation detectiion method aand informatiion processinng technologyy researcheshavebeenn done for reaal time structtural shape deetection, recoonstruction annd dynamic vvisualization.. Keytechhnology reseaarch and expperiment valiidation are ddone. Aggressive investiggates are donne forFBGG sensing teechnology, kiinetic analyssis, FBG sennsor multipleexing technoology and seensorconffiguration strrategy. Thetransformatiion relationshhip betweenn discrete strrain and disscretecurvvature is anallyzed. Three--dimensionall reconstructiion method bbased on orthhogonal curvvatureandits implemeentation methhod is studiedd. FBG senssor array andd an experimmental structuure isdesiggned, then aan experimenntal platformm is construccted and a mmonitoring sooftware systeem isdeveeloped to veerify the feaasibility andeffectivenesss of relatedtechniques.The disserttationconssists four paarts: kineticanalysis annd FBG sennsor array ddistributiondesign, struucture reconstruction method and dynamic visualization for space surfaces and curves, experimentalmodel design and software development, and experimental platform construction andexperimental validation. The main work and contributions in the dissertation are listed asfollows:(1) By attaching distributed FBG sensor array on structure surface, an experimental FBGsmart aircraft is constructed for an experimental frame structure with two additional airfoils.With the development of shape perception reconstruction and visualization software platform, aset of FBG smart structure shape perception, reconstruction and visualization monitoringexperiment system has been formed.(2) By structural dynamic analysis, combined with finite element analysis, placementprinciples for sensor arrays are explored and established for FBG placement of FBG flexiblesmart structure.(3) Transformation relationship between discrete strain information detected by FBG sensorarray and discrete curvature is analyzed. Plane curve fitting method based on the curvatureinformation is proposed and several recursive algorithms are compared. Meanhile micro surfacebased reconstruction algorithm is explored.(4) Three-dimensional shape reconstruction theories and methods using orthogonal discretecurvature information are studied in depth, detailed derivation process is given. Continuousinterpolation method for discrete curvature data is proposed to realize continuous structuresurface curvature information acquisition. Simulation experiment analysis shows that thealgorithms using the curvature information detected by FBG sensor arrays for reconstruction ofspace curves and surfaces is feasible and effective.(5) Smart flexible structure experimental model object design and construction scheme isgiven. The FBG smart rod modular design method, packaging and calibration techniques,embedding and encapsulation, and unit verification experiments are illustrated.(6) Experimental model structure experimental platform construction, experimental setupselection and configuration, and experimental verification scheme is analyzed. A structure shapereconstruction and visualization software platform is constructed based on Visual C++8.0withOpenGL technology.(7) With the developed experimental platform, experimental analysis and verification aredone. Experimental results show that shape perception and visual active monitoring based onFBG sensor array is feasible. The reconstruction performance is very good, and could reflectstructure deformation state and low frequency vibration shape relatively accurately, which completely reached the expected target. The results from this dissertation could provideadvanced innovative technology ideas for real-time active monitoring of key aerospace structuraldeformation and vibration shape.