行星齿轮传动电动滚筒设计(全套含CAD图纸)
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11OptimalDesignofCompliantTrailingEdgeforShapeChangingAbstract:AdaptivewingshavelongusedsmoothmorphingtechniqueofcompliantleadingandtrailingedgetoimprovetheiraerodynamiccharacteristicsThispaperintroducesasystematicapproachtodesigncompliantstructurestocarryoutrequiredshapechangesunderdistributedpressureloadsInordertominimizethedeviationofthedeformedshapefromthetargetshape,thismethodusesMATLABandANSYStooptimizethedistributedcompliantmechanismsbywayofthegroundapproachandgeneticalgorithm(GA)toremovetheelementspossessiveofverylowstressesIntheoptimizationprocess,manyfactorsshouldbeconsideredsuchasairloads,inputdisplacements,andgeometricnonlinearities。DirectsearchmethodisusedtolocallyoptimizethedimensionandinputdisplacementaftertheGAoptimization。Theresultantstructurecouldmakeitsshapechangefrom0to93degreesTheexperimentaldataofthemodelconfirmsthefeasibilityofthisapproachKeywords:adaptivewing;compliantmechanism;geneticalgorithm;topologyoptimization;distributedpressureload;geometricnonlinearity1Introduction:AsconventionalairfoilcontoursareusuallydesignedwithspecificliftcoefficientsandMachnumbers,theycouldnotchangeinaccordancewiththeenvironmentchangingSiclariandAustinindicatedthatthevariablecambertrailingedgewouldproducethedragaboutsixtypercentlessthantheconventionalfixedcamberairfoilTherearethreemethodsusedtodesignablecamberwingsOfthemoneisconventionalhingedmechanism,which,however,willcreatediscontinuitiesoverthewingssurfaceleadingtoearlierairflowseparationanddragincreaseTheothersaresmartmaterialandthecompliantmechanism,ofwhichbothcouldrealizesmoothshapechangingNevertheless,comparedtothecompliantmechanism,thesmartmaterialmadeactuatorshavemanydisadvantages,suchasdeficientinenergy,slowinresponse,stronginhysteresis,limitedbytemperature,anddifficulttocontroltoomanyactuatorsMusolfffromIndustryUniversityofBerlin12usedNiTishapememoryalloywiretomakeanadaptivevariablecamberwing,whichcouldquicklychangeitsshape,butcouldnotperformhighlyfrequentalterationbecauseofitsresiliencedependentontheheatexchangewiththeoutsideenvironment。Compliantmechanismisakindofone-pieceflexiblestructure,whichcantransfermotionandpowerthroughitsownelasticdeformationItisnotonlyflexibleenoughtodeform,butalsohasenoughstiffnesstowithstandexternalloadsThankstoitsjointfreenature,itdoesnothavethetroublesomeproblemsconfrontedbyconventionalmechanismsuchasfriction,lubrication,noiseandrecoiling,therebyachievingsmoothshapechanging.In1994,Kota,aprofessorfromUniversityofMichigan,firstlypointedoutthatcompliantmechanismcouldbeusedtocontrolstaticshapechangingunderthesponsorshipoftheAirForceOficeofScientificResearchinUSASaggereandKotasuggestedanewmethodtodesigncompliantadaptivestructures,whichmadetheleastsquareerrorsbetweentheshapechangedcurveandthetargetcurveastheobjectivefunctionforoptimizationBasedontheirwork,LuputforwardaloadpathrepresentationmethodHowever,herworkwaslimitedtoonlylinearanalysisunderconsiderationofnodalloadsGoodfromVirginiaPolytechnicInstituteofStateUniversityusedthecompliantmechanismandtheMovingAsymptotesmethodtodesignthefuselagetailwithintheallowablerangeofitstipmaximaldeflectionKotaandHetrickin2004designedacomplianttrailingedgeonthebaseoftheF16sdata,whichcanchangefrom0。to15。andobtainedapatentCampanilefromGermanAerospaceCenterpresentedamodalproceduretodesignsyntheticflexiblemechanismsforairfoilshapecontrol,andpointedoutthatthefutureresearchshouldtakeintoaccounttheairloadandthegeometricnonlinearityBuhlfromRisoNationalLaboratoryoftheWindEnergyDepartmentinDenmarkusedtheSIMPmethodandgeometricallynonlinearfiniteelementmethodtodesigncomplianttrailingedgeflapsFlxSysIncin2006producedanadaptivecompliantwing,whichstoodthetestontheWhiteKnightairplaneTheresults13indicatedthatthecomplianttrailingedgecouldchange+10InChina,theresearchofadaptivewinghasbeenconcentratedonsmartmaterialandconventionalmechanismFewpeople,itseems,haveworkedondesigningadaptivewingswiththecompliantmechanismYangisanexceptionHeanalyzedtheactiveaeroelasticwingsbasedontheaeroservoelasticitytechnologyChenandHuangseparatelyinvestigatedthemorphingofthecompliantleadingedgefromtheviewpointsofdiscretenessandcontinuity.ThispaperpresentsamethodtodesigntheshapechangeablestructurebyMATLABandANSYSassociatedwithdistributedcompliantmechanismonthebaseofthegroundstructureapproachandgeneticalgorithm(GA)takingintoaccounttheexternaldistributedloadsandgeometricnonlinearity.2OptimizationProcess:21DefiningthetrailingedgemodelandobjectivefunctionAsshowninFig1,bothcurvesrepresenttwoidealshapesofthetrailingedgeinthedifferentflyingstatesOnesidepoint)ofthestructureissupposedtobefixed,andtheothersidepoint)tobeslidinghorizontally.Firstly,thedesigndomainshouldbedefinedbytheinitialcurveshapetheinputlocationandtheboundaryconditionsThenitisdividedwithabeamelementnetworksimulatingthebirdsfeatherasshowninFig2Thisistermedthepartialgroundstructuremethod.Fig1InitialshapeandtargetshapeFig2DiscretizationofthedesigndomainThesimplestandmosteffectivewaytomanufacturetheplanarcompliantmechanismistousewirecuttingtechnologyIntheoptimizationprogram,alltheelementsareofrectangularbeamswiththesamewidthequaltothethicknessofthematerial,everybeamsheightbeingadesignvariable14Inordertomakethestructuresdeformationcomeclosetothetargetshapecurve,theleastsquareerror(LSE)betweenthedeformedcurveandthetargetcurveisdefinedastheobjectivefunctionLSEisthesumofsquaresofpositiondifferencesofvariouspointsalongthecurvesItsexpressioniswhereI(=1,2,P)isthenumberofthepointsalongthecurves,PisthetotalnumberofpointsandarethecoordinatesofithnodeonthetargetanddeformedboundarycurverespectivelyTheconstraintsareWhereJ(=1,2,)isthenumberofelements,missthetota1numberofelements,hithedimensionvariable,hminandhmaxarethelowerandupperboundsoftheelementbeamheightforallelementswiththevaluedependentonmanufacturing,hbtheheightoftheboundaryelements,themaximumnoda1deformationofthenodesonthecurveboundarywhentheinputpointisinactive,andshouldbesmallerthandtoensurestructurestiffness,dtheallowablemaximumdisplacementwhentheinputpointisinactive,Omaxthemaximumstressofal1theelementswhichmustbesmallerthanTjtopreventyielding,Tjthetopologyvariableequalto1,orelse0whentheelementiseliminated22GAoptimizationGAisanoptimizationmethodwhichsimulatestheheuristicselectionruleinnature,wherethefittestlivingthingshavethemostchancetosurvive,buttheinferioronesalsohavetheopportunitytoexistDifferentfromthecontinuousoptimizationmethod,itdoesnotrequirethegradient-basedinformationoftheobjectivefunction.15EveryelementcouldbeexpressedasatopologyvariableandadimensionvariableTherefore,eachindividua1couldbecodedasfollowswhere,2isthenumberofelementsexcepttheboundaryonesWiththesameheights,theboundaryelementsthroughouttheoptimizingprocessarerepresentedbyonlyonevariable,hb.ThefitnessisthecriterionoftheGAoptimizationItcouldbetransformedfromtheobjectivefunctionintowhereisacoefficientdecidingthecompulsiveselectionofthebetterindividua1Thesmallerthevalue,themoredifferentwouldbebetweenthetwoindividualsfitnessthusincreasingthecompulsivenessofchoosingtheindividualofhigherfitnessTheselectionofcontrolparametersplaysanimportantroleintheconvergenceoftheGAGenerallyspeakingthecrossprobabilityranges040099;themutationprobabilityis000001-001andthenumberofindividuals10200Thevariablewouldbeupdatedthroughthecrossoverandmutation,sothepossibledesigncouldgenerateintheGAprocess23Finiteelementanalysis(FEA)Becauseofthelimiteddesignvariablesandthetargetfunction,theoptimizationmoduleofFEAsoftwarecouldnotbeusedtodesignthecompliantmorphingmechanismTherefore,thispaperprogrammedtheGAinMATLABandtheFEAinANSYSIntheFEA,takingonlyaccountofgeometricnonlinearitiesandthematerialbeingoflinearelasticity,ANSYScouldsolvethenodedisplacementsandtheelementstressesThenbydeletingtheelementswithlowstress,thefitnesscouldbecalculatedFig3showsthedetailedprocess16Fig3Flowchartofthestructuraloptimizationprogram24SecondoptimizationAlthoughtheGAcouldoptimizethetopologyanddimensionsimultaneouslyinalargesolutionspace,thedimensionusuallycouldnotdirectlyconvergetotheoptimizationInordertosolvethisproblem,aftertheGA,theDirectSearchmethodshouldbeusedtofindthebestvaluesoftheinputdisplacementandthedimensionsoftheelementswhichremainintheresultsaftertheGAFormorphingofcompliantmechanism,Fig3describesthewholeoptimizationprocessItmainlycontainsinitializationofthedesigndomain,FEA,GAoptimizationandsecondoptimization.3PresentationofResults:AdoptedfromRef,thesizesoftheinitialandthetargettrailingedgearereducedbysixtypercent,I1ab1e1liststhedesignparameters.Becausethedisplacementisusedastheinput,thenonlinearanalysiscouldhardlyconvergeandthestressoftheinitia1solutionsisverylargeWhichshouldbeconsideredafterthirtiethgeneration.17Table1DesignparametersFig4andFig5illustratetheresultsfromtheGAoptimizationandthesecondoptimizationrespectivelyFig4ResultsaftertheGAoptimizationFig5ResultsafterthesecondoptimizationFormTable2,itcouldbefoundthatthroughthesecondoptimizationoftheinputdisplacementandthedimension,theLSEisreducedby13528mmandimprovedby313Thealteredangleisincreasedby10493Table2Resultsafterthetwooptimization18Fig6StabilityoffinaloptimalstructureFig6showstheinfluencesoftheparameterswhentheoutsidedistributedpressureloadchangesfrom0to10Nmmandtheinputdisplacementremains113897mmontheoptimalstructureItcouldbeseenthattheoptimalstructurehasagoodstabilityiftheloadiskeptintherangeOf05NmmAstheexternalloadexceeds5Nmm,themaxstressislikelytoexceedtheyieldstress19BecausethisoptimizationprogramisbasedontheMATLABandANSYSinordertoverifytheresultsanattemptismadetointroducetheanalyticalresultsoftheoptimizedstructureintoANSYSandPATRANrespectively,andthenacomparisonismadebetweenthemAsshowninFig7andFig8,thetwoalteredshapesareingoodagreement:forinANSYSthetipdisplacementis5497mmandinPATRRAN5450mmTheminordifferencebetweenthemisfromthesoftwareFig7ResultsofFEAinANSYSFig8ResultsofFEAinPATRANOntheotherhand,amodelismadebywirecuttingtechnologytoverifytheanalyticalresultsThematerialofthemode1identicalwiththatofthedesign,is5mmthickIntheexperiment,thedistrib
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