瞬态冲击载荷等效转换为集中载荷的优化方法

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²û}wIHlb:Æ-}w„¹Õ\8SfÑå›füYë‘Z2010t3INorthwesternPolytechnicalUniversityDissertationforMasterDegreeofPhilosophyinEngineeringTheoptimizedmethodoftransientimpactloadconvertedtoequivalentconcentratedloadsCandidate:ChangXiaotongSupervisor:ProfessorYanYunjuSpeciality:EngineeringMechanicsXi’an,P.R.ChinaMarch2010å'fUëfMº‡XIX'‹ü9{„ÞLh(ØÞLÇ-×B„¨jð}wÙÍ}wÙÞLhӄ,«Êv¾&eˆ'qi'àd(0bÇ/¨ÕŒ°B„¨›f¯ƒ—0ÞL¶
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ºåzýI¹b:ÐØH‡,‡ùÆW—ÕÛL†9Ûv(*ðýpùv'ýÛL†KÕÙIW—ՏŒ PCoöøÓ”(ŽÓ„}wÂpî˜-p—‹Á†Ù¹Õ„ H'Œï('ÏÇW—Õù@ é€À/›„'
\(MnÊøMÛL}wlb„Hœ—0†ˆ'ÐØvößsGïîï§6(1.0dBå…ï:ÞLh„0bՌЛÍ }¹Õs.Í}wlbÂpW—Õ PCÕå'fUëfMº‡XIIå'fUëfMº‡ABSTRACTIIIAbstractManyaeronauticorspaceflightweaponsuchasLarge-scalemissilesalwayswithstandcomplexaerodynamicloadswhentheyareinhigh-speedflight.Theseloadsmaybringagreatrisktothesafetyoftheequipmentsandtheaircraftstructureitself,thusthegroundvibrationtestisnecessarytoreproducedthecomplexdynamicenvironmentortobeequivalentwiththestructuralvibrationresponseoftheflightairframe,soastoassessmentthesafetyoftheaircraftanditsequipment.Theseinvolveaseriesofdifficultissuessuchastheloadidentificationandloadequivalent.Allwecareaboutistheresponseoftheaircraftratherthantheloaditself,thespecificformoftheloadandthecomplexinteractionsbetweenandthestructurewereignored,andthecomplexloadwasreplacedbysomeincentiveloadswithsimpleformsinthispaperwhichisbasedonthemethodofstructuralresponseequivalent.Accordingtomodaldecompositiontheory,thestructuralvibrationresponseoflinearandsmalldampingsysteminthetransientvibrationcanbeapproximatedtoseveralordersofmodalvibration.Therefore,theunsteadyloadonthestructurecanbeconvertedtoconcentratedloadsequivalentlyifweimposedsomesimpleharmonicconcentratedloadswhosefrequenciesareequaltothenaturalfrequenciesofthesemodesofvibration,andoptimizedtheparametersoftheseconcentratedloads.Geneticalgorithmisahighlyefficientbionicoptimizationalgorithmwhichhasbeenwidelyusedinengineeringoptimization,artificialintelligence,etc.Toimprovetheefficiencyofoptimization,thestandardgeneticalgorithmwasimprovedinthispaperandamulti-peakfunctionwasusedtotestitsperformance.Finally,theprocedureofthisgeneralizedgeneticalgorithmandfiniteelementsoftwarecombinationwasusedintheparametersoptimizationproblemofstructuralloads.Anumericalexampleprovedtheeffectivenessandavailabilityofthisapproach.Aftertheoptimizationusedofgeneticalgorithmtochoosetheamplitudesoftheharmonicexcitingloads,theactingpositionsandtheinitialphases,theeffectofloadtransferhavebeengreatlyimproved:itsaverageerrorintime-domaincanbecontrolledinlessthan1.0dB,thus,thispapercanprovideareferenceloadingmethodtogroundtestsforaircraft.Keywords:Loadtransfer,Parameteroptimization,Geneticalgorithm,Finiteelementmethodå'fUëfMº‡ABSTRACTIVå'fUëfMº‡îUVîUX..............................................................IAbstract.........................................................III,àêº......................................................11.1.........................................................11.2}wÆ+v„ÌoÊý…v‚µ..........................21.2.1}wÆ+„ýv‚µ.................................31.2.2}wÆ+„ý…v‚µ.................................41.3° }wÆ+¹ÕÊvX(Ë............................51.3.1¨
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