机械专业毕业设计（论文）外文翻译-立体光照成型的注塑模具工艺的综合模拟

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DLOADBOUNDARYCONDITIONSCAUSESIGNICANTDISTORTIONSINTHESLMOLDTHESIMULATIONSTEPSAREASFOLLOWS1THEPARTGEOMETRYISMODELEDASASOLIDMODEL,WHICHISTRANSLATEDTOALEREADABLEBYTHEOWANALYSISPACKAGE2SIMULATETHEMOLDLLINGPROCESSOFTHEMELTINTOAPHOTOPOLYMERMOLD,WHICHWILLOUTPUTTHERESULTINGTEMPERATUREANDPRESSUREPROLES3STRUCTURALANALYSISISTHENPERFORMEDONTHEPHOTOPOLYMERMOLDMODELUSINGTHETHERMALANDLOADBOUNDARYCONDITIONSOBTAINEDFROMTHEPREVIOUSSTEP,WHICHCALCULATESTHEDISTORTIONTHATTHEMOLDUNDERGODURINGTHEINJECTIONPROCESS4IFTHEDISTORTIONOFTHEMOLDCONVERGES,MOVETOTHENEXTSTEPOTHERWISE,THEDISTORTEDMOLDCAVITYISTHENMODELEDCHANGESINTHEDIMENSIONSOFTHECAVITYAFTERDISTORTION,ANDRETURNSTOTHESECONDSTEPTOSIMULATETHEMELTINJECTIONINTOTHEDISTORTEDMOLD5THESHRINKAGEANDWARPAGESIMULATIONOFTHEINJECTIONMOLDEDPARTISTHENAPPLIED,WHICHCALCULATESTHENALDISTORTIONSOFTHEMOLDEDPARTINABOVESIMULATIONOW,THEREARETHREEBASICSIMULATIONMODULES22FILLINGSIMULATIONOFTHEMELT221MATHEMATICALMODELINGINORDERTOSIMULATETHEUSEOFANSLMOLDINTHEINJECTIONMOLDINGPROCESS,ANITERATIVEMETHODISPROPOSEDDIFFERENTSOFTWAREMODULESHAVEBEENDEVELOPEDANDUSEDTOACCOMPLISHTHISTASKTHEMAINASSUMPTIONISTHATTEMPERATUREANDLOADBOUNDARYCONDITIONSCAUSESIGNIFICANTDISTORTIONSINTHESLMOLDTHESIMULATIONSTEPSAREASFOLLOWS1THEPARTGEOMETRYISMODELEDASASOLIDMODEL,WHICHISTRANSLATEDTOAFILEREADABLEBYTHEFLOWANALYSISPACKAGE2SIMULATETHEMOLDFILLINGPROCESSOFTHEMELTINTOAPHOTOPOLYMERMOLD,WHICHWILLOUTPUTTHERESULTINGTEMPERATUREANDPRESSUREPROFILES3STRUCTURALANALYSISISTHENPERFORMEDONTHEPHOTOPOLYMERMOLDMODELUSINGTHETHERMALANDLOADBOUNDARYCONDITIONSOBTAINEDFROMTHEPREVIOUSSTEP,WHICHCALCULATESTHEDISTORTIONTHATTHEMOLDUNDERGODURINGTHEINJECTIONPROCESS4IFTHEDISTORTIONOFTHEMOLDCONVERGES,MOVETOTHENEXTSTEPOTHERWISE,THEDISTORTEDMOLDCAVITYISTHENMODELEDCHANGESINTHEDIMENSIONSOFTHECAVITYAFTERDISTORTION,ANDRETURNSTOTHESECONDSTEPTOSIMULATETHEMELTINJECTIONINTOTHEDISTORTEDMOLD5THESHRINKAGEANDWARPAGESIMULATIONOFTHEINJECTIONMOLDEDPARTISTHENAPPLIED,WHICHCALCULATESTHEFINALDISTORTIONSOFTHEMOLDEDPARTINABOVESIMULATIONFLOW,THEREARETHREEBASICSIMULATIONMODULES22FILLINGSIMULATIONOFTHEMELT221MATHEMATICALMODELINGCOMPUTERSIMULATIONTECHNIQUESHAVEHADSUCCESSINPREDICTINGFILLINGBEHAVIORINEXTREMELYCOMPLICATEDGEOMETRIESHOWEVER,MOSTOFTHECURRENTNUMERICALIMPLEMENTATIONISBASEDONAHYBRIDFINITEELEMENT/FINITEDIFFERENCESOLUTIONWITHTHEMIDDLEPLANEMODELTHEAPPLICATIONPROCESSOFSIMULATIONPACKAGESBASEDONTHISMODELISILLUSTRATEDINFIG21HOWEVER,UNLIKETHESURFACE/SOLIDMODELINMOLDDESIGNCADSYSTEMS,THESOCALLEDMIDDLEPLANEASSHOWNINFIG21BISANIMAGINARYARBITRARYPLANARGEOMETRYATTHEMIDDLEOFTHECAVITYINTHEGAPWISEDIRECTION,WHICHSHOULDBRINGABOUTGREATINCONVENIENCEINAPPLICATIONSFOREXAMPLE,SURFACEMODELSARECOMMONLYUSEDINCURRENTRPSYSTEMSGENERALLYSTLFILEFORMAT,SOSECONDARYMODELINGISUNAVOIDABLEWHENUSINGSIMULATIONPACKAGESBECAUSETHEMODELSINTHERPANDSIMULATIONSYSTEMSAREDIFFERENTCONSIDERINGTHESEDEFECTS,THESURFACEMODELOFTHECAVITYISINTRODUCEDASDATUMPLANESINTHESIMULATION,INSTEADOFTHEMIDDLEPLANEACCORDINGTOTHEPREVIOUSINVESTIGATIONS46,FILLINGGOVERNINGEQUATIONSFORTHEFLOWANDTEMPERATUREFIELDCANBEWRITTENASWHEREX,YARETHEPLANARCOORDINATESINTHEMIDDLEPLANE,ANDZISTHEGAPWISECOORDINATEU,V,WARETHEVELOCITYCOMPONENTSINTHEX,Y,ZDIRECTIONSU,VARETHEAVERAGEWHOLEGAPTHICKNESSESAND,CPT,KTREPRESENTVISCOSITY,DENSITY,SPECIFICHEATANDTHERMALCONDUCTIVITYOFPOLYMERMELT,RESPECTIVELYFIG21ADSCHEMATICPROCEDUREOFTHESIMULATIONWITHMIDDLEPLANEMODELATHE3DSURFACEMODELBTHEMIDDLEPLANEMODELCTHEMESHEDMIDDLEPLANEMODELDTHEDISPLAYOFTHESIMULATIONRESULTINADDITION,BOUNDARYCONDITIONSINTHEGAPWISEDIRECTIONCANBEDEFINEDASWHERETWISTHECONSTANTWALLTEMPERATURESHOWNINFIG2ACOMBININGEQS14WITHEQS56,ITFOLLOWSTHATTHEDISTRIBUTIONSOFTHEU,V,T,PATZCOORDINATESSHOULDBESYMMETRICAL,WITHTHEMIRRORAXISBEINGZ0,ANDCONSEQUENTLYTHEU,VAVERAGEDINHALFGAPTHICKNESSISEQUALTOTHATAVERAGEDINWHOLEGAPTHICKNESSBASEDONTHISCHARACTERISTIC,WECANDIVIDETHEWHOLECAVITYINTOTWOEQUALPARTSINTHEGAPWISEDIRECTION,ASDESCRIBEDBYPARTIANDPARTIIINFIG2BATTHESAMETIME,TRIANGULARFINITEELEMENTSAREGENERATEDINTHESURFACESOFTHECAVITYATZ0INFIG2B,INSTEADOFTHEMIDDLEPLANEATZ0INFIG2AACCORDINGLY,FINITEDIFFERENCEINCREMENTSINTHEGAPWISEDIRECTIONAREEMPLOYEDONLYINTHEINSIDEOFTHESURFACESWALLTOMIDDLE/CENTERLINE,WHICH,INFIG2B,MEANSFROMZ0TOZBTHISISSINGLESIDEDINSTEADOFTWOSIDEDWITHRESPECTTOTHEMIDDLEPLANEIEFROMTHEMIDDLELINETOTWOWALLSINADDITION,THECOORDINATESYSTEMISCHANGEDFROMFIG2ATOFIG2BTOALTERTHEFINITEELEMENT/FINITEDIFFERENCESCHEME,ASSHOWNINFIG2BWITHTHEABOVEADJUSTMENT,GOVERNINGEQUATIONSARESTILLEQS14HOWEVER,THEORIGINALBOUNDARYCONDITIONSINTHEGAPWISEDIRECTIONAREREWRITTENASMEANWHILE,ADDITIONALBOUNDARYCONDITIONSMUSTBEEMPLOYEDATZBINORDERTOKEEPTHEFLOWSATTHEJUNCTUREOFTHETWOPARTSATTHESAMESECTIONCOORDINATE7WHERESUBSCRIPTSI,IIREPRESENTTHEPARAMETERSOFPARTIANDPARTII,RESPECTIVELY,ANDCMIANDCMIIINDICATETHEMOVINGFREEMELTFRONTSOFTHESURFACESOFTHEDIVIDEDTWOPARTSINTHEFILLINGSTAGEITSHOULDBENOTEDTHAT,UNLIKECONDITIONSEQS7AND8,ENSURINGCONDITIONSEQS9AND10AREUPHELDINNUMERICALIMPLEMENTATIONSBECOMESMOREDIFFICULTDUETOTHEFOLLOWINGREASONS1THESURFACESATTHESAMESECTIONHAVEBEENMESHEDRESPECTIVELY,WHICHLEADSTOADISTIN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TITUTINGTHEAPPROPRIATELINEARSHAPEFUNCTIONSINTOEQ25,THELINEARBOUNDARYELEMENTFORMULATIONFORTHEMOLDDEFORMATIONMODELISOBTAINEDTHEEQUATIONISAPPLIEDATEACHNODEONTHEDISCRETIZEDMOLDSURFACE,THUSGIVINGASYSTEMOF3NLINEAREQUATIONS,WHERENISTHETOTALNUMBEROFNODESEACHNODEHASEIGHTASSOCIATEDQUANTITIESTHREECOMPONENTSOFDISPLACEMENT,THREECOMPONENTSOFTRACTION,ATEMPERATUREANDAHEATFLUXTHESTEADYSTATETHERMALMODELSUPPLIESTEMPERATUREANDFLUXVALUESASKNOWNQUANTITIESFOREACHNODE,ANDOFTHEREMAININGSIXQUANTITIES,THREEMUSTBESPECIFIEDMOREOVER,THEDISPLACEMENTVALUESSPECIFIEDATACERTAINNUMBEROFNODESMUSTELIMINATETHEPOSSIBILITYOFARIGIDBODYMOTIONORRIGIDBODYROTATIONTOENSUREANONSINGULARSYSTEMOFEQUATIONSTHERESULTINGSYSTEMOFEQUATIONSISASSEMBLEDINTOAINTEGRATEDMATRIX,WHICHISSOLVEDWITHANITERATIVESOLVER24SHRINKAGEANDWARPAGESIMULATIONOFTHEMOLDEDPARTINTERNALSTRESSESININJECTIONMOLDEDCOMPONENTSARETHEPRINCIPALCAUSEOFSHRINKAGEANDWARPAGETHESERESIDUALSTRESSESAREMAINLYFROZENINTHERMALSTRESSESDUETOINHOMOGENEOUSCOOLING,WHENSURFACELAYERSSTIFFENSOONERTHANTHECOREREGION,ASINFREEQUENCHINGBASEDONTHEASSUMPTIONOFTHELINEARTHERMOELASTICANDLINEARTHERMOVISCOELASTICCOMPRESSIBLEBEHAVIOROFTHEPOLYMERICMATERIALS,SHRINKAGEANDWARPAGEAREOBTAINEDIMPLICITLYUSINGDISPLACEMENTFORMULATIONS,ANDTHEGOVERNINGEQUATIONSCANBESOLVEDNUMERICALLYUSINGAFINITEELEMENTMETHODWITHTHEBASICASSUMPTIONSOFINJECTIONMOLDING12,THECOMPONENTSOFSTRESSANDSTRAINAREGIVENBYTHEDEVIATORICCOMPONENTSOFSTRESSANDSTRAIN,RESPECTIVELY,AREGIVENBYUSINGASIMILARAPPROACHDEVELOPEDBYLEEANDROGERS13FORPREDICTINGTHERESIDUALSTRESSESINTHETEMPERINGOFGLASS,ANINTEGRALFORMOFTHEVISCOELASTICCONSTITUTIVERELATIONSHIPSISUSED,ANDTHEINPLANESTRESSESCANBERELATEDTOTHESTRAINSBYTHEFOLLOWINGEQUATIONWHEREG1ISTHERELAXATIONSHEARMODULUSOFTHEMATERIALTHEDILATATIONALSTRESSESCANBERELATEDTOTHESTRAINASFOLLOWSWHEREKISTHERELAXATIONBULKMODULUSOFTHEMATERIAL,ANDTHEDEFINITIONOFANDISIFT0,APPLYINGEQ27TOEQ29RESULTSINSIMILARLY,APPLYINGEQ31TOEQ28ANDELIMINATINGSTRAINXXZ,TRESULTSINEMPLOYINGALAPLACETRANSFORMTOEQ32,THEAUXILIARYMODULUSRISGIVENBYUSINGTHEABOVECONSTITUTIVEEQUATIONEQ33ANDSIMPLIFIEDFORMSOFTHESTRESSESANDSTRAINSINTHEMOLD,THEFORMULATIONOFTHERESIDUALSTRESSOFTHEINJECTIONMOLDEDPARTDURINGTHECOOLINGSTAGEISOBTAINBYEQUATION34CANBESOLVEDTHROUGHTHEAPPLICATIONOFTRAPEZOIDALQUADRATUREDUETOTHERAPIDINITIALCHANGEINTHEMATERIALTIME,AQUASINUMERICALPROCEDUREISEMPLOYEDFOREVALUATINGTHEINTEGRALITEMTHEAUXILIARYMODULUSISEVALUATEDNUMERICALLYBYTHETRAPEZOIDALRULEFORWARPAGEANALYSIS,NODALDISPLACEMENTSANDCURVATURESFORSHELLELEMENTSAREEXPRESSEDASWHEREKISTHEELEMENTSTIFFNESSMATRIX,BEISTHEDERIVATIVEOPERATORMATRIX,DISTHEDISPLACEMENTS,ANDREISTHEELEMENTLOADVECTORWHICHCANBEEVALUATEDBYTHEUSEOFAFULLTHREEDIMENSIONALFEMANALYSISCANACHIEVEACCURATEWARPAGERESULTS,HOWEVER,ITISCUMBERSOMEWHENTHESHAPEOFTHEPARTISVERYCOMPLICATEDINTHISPAPER,ATWODIMENSIONALFEMMETHOD,BASEDONSHELLTHEORY,WASUSEDBECAUSEMOSTINJECTIONMOLDEDPARTSHAVEASHEETLIKEGEOMETRYINWHICHTHETHICKNESSISMUCHSMALLERTHANTHEOTHERDIMENSIONSOFTHEPARTTHEREFORE,THEPART