FE MODEL VALIDATION FOR STRUCTURAL DYNAMICS创新结构力学

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1、ImperialCollegeofScience,TechnologyandMedicineUniversityofLondonFEMODELVALIDATIONFORSTRUCTURALDYNAMICSbyGanChenAthesissubmittedtotheUniversityofLondonforthedegreeofDoctorofPhilosophyDynamicsSectionDepartmentofMechanicalEngineeringLondon,SouthKensingtonApril20011AbstractThist

2、hesisdescribesstudiesoffiniteelement(FE)modelvalidationmethodsforstructuraldynamics.ThereareusuallydiscrepanciesbetweenpredictionsofthestructuraldynamicpropertiesbasedonaninitialFEmodelandthoseyieldedbyexperimentaldatafromtestsontheactualstructure.Inordertomakepredictionsfro

3、mthemodelsuitableforevaluatingthedynamicpropertiesofthestructure,andthustooptimiseitsdesign,themodelhastobevalidated.Theprocessofmodelvalidationandtheindividualstepsthatmakeupthisprocessarestudiedthroughtheoreticalanalysisandcasestudies.Ageneralstrategyformodelvalidationispr

4、esentedintheintroductiontothethesis,describingthevalidationprocessasasequenceofdistinctsteps.Astudyofthestrategypresentedattheendofthethesisshowsmultipleapproachesformodelvalidation.Usingexperienceobtainedfromvalidatingmodelsofexamplestructuresforconstructingandvalidatingthe

5、modelofanewdesignofasimilarstructurecouldacceleratetheprocessofFEmodelvalidation,andthereforebenefitindustrybyreducingthetimeofthedesign-examine-redesignloop.Throughcasestudies,anewperspectiveontheperformanceofmodelupdatingispresentedinthisworkshowingthatmodelupdatingcanonly

6、minimisethediscrepanciescausedbyparametererrorsinthemodel.However,modelupdatingprocedurescannotreducediscrepanciescausedbydiscretisationerrorsand/orconfigurationerrorswithoutlosingthephysicalmeaningoftheupdatingparameters.Inordertomakesurethatamodelissuitableforbeingsubjecte

7、dtotheupdatingstep,themodelmustfirstbeverified.Twoverificationmethods,aconvergencecheckbyusingtwodifferentformulaeforconstructingthemassmatrixofeachelementandaconfigurationcheckbyprojectingexperimentalmodeshapesontothesubspacespannedbyFEmodelpredictedeigenvectors,areproposed

8、todealwithdiscretisationerrorsandconfigurationerrorsrespectivelyinFEmodels.