外文翻译--机械设计-新型搅拌机.doc

MechanicalDesign-ThenewblenderTheDesignProcess:Designingstartswithaneedreal.Existingapparatusmayneedimprovementsindurability,efficiency,weight,speed,orcost.Newapparatusmaybeneededtoperformafunctionpreviouslydonebymen,suchascomputation,assembly,orservicing.WiththeobjectivewhollyorpartlyInthedesignpreliminarystage,shouldallowtodesignthepersonnelfullytodisplaythecreativity,noteachkindofrestraint.Evenifhashadmanyimpracticalideas,alsocaninthedesignearlytime,namelyinfrontoftheplanblueprintiscorrected.Onlythen,onlythendoesnotsendtostopsuptheinnovationthementality.Usually,mustproposeseveralsetsofdesignproposals,thenperformthecomparison.Hasthepossibilityverymuchintheplanwhichfinallydesignated,hasusedcertainnotinplansomeideaswhichaccepts.Whenthegeneralshapeandafewdimensionsoftheseveralcomponentsbecomeapparent,analysiscanbegininearnest.Theanalysiswillhaveasitsobjectivesatisfactoryorsuperiorperformance,plussafetyanddurabilitywithminimumweight,andacompetitivecost.Optimumproportionsanddimensionswillbesoughtforeachcriticallyloadedsection,togetherwithabalancebetweenthestrengthsoftheseveralcomponents.Materialsandtheirtreatmentwillbechosen.Theseimportantobjectivescanbeattainedonlybyanalysisbasedupontheprinciplesofmechanics,suchasthoseofstaticforreactionforcesandfortheoptimumutilizationoffriction；ofdynamicsforinertia,acceleration,andenergy；ofelasticityandstrengthofmaterialsforstressanddeflection；ofphysicalbehaviorofmaterials；andoffluidmechanicsforlubricationandhydrodynamicdrives.Theanalysesmaybemadebythesameengineerwhoconceivedthearrangementofmechanisms,or,inalargecompany,theymaybemadebyaseparateanalysisdivisionorresearchgroup.Designisareiterativeandcooperativeprocess,whetherdoneformallyorinformally,andtheanalystcancontributetophasesotherthanhisown.Productdesignrequiresmuchresearchanddevelopment.ManyConceptsofanideamustbestudied,tried,andtheneitherusedordiscarded.Althoughthecontentofeachengineeringproblemisunique,thedesignersfollowthesimilarprocesstosolvetheproblems.Productliabilitysuitsdesignersandforcedinmaterialselection,usingthebestprogram.Intheprocessofmaterial,themostcommonproblemsforfive(a)dontunderstandornotuseaboutthelatestapplicationmaterialstothebestinformation,(b)failedtoforeseeandconsiderthereasonableusematerialmay(suchaspossible,designersshouldfurtherforecastandconsiderduetoimproperuseproducts.Inrecentyears,manyproductsliabilityinlitigation,theuseofproductsandhurttheplaintiffaccusedmanufacturer,andwonthedecision),(c)ofthematerialsusedallorsomeofthedata,data,especiallywhentheuncertaintylong-termperformancedataisso,(d)qualitycontrolmethodisnotsuitableandunproven,(e)bysomecompletelyincompetentpersonschoosematerials.Throughtotheabovefivequestionsanalysis,mayobtainthesequestionsisdoesnothavethesufficientreasonexistencetheconclusion.Mayforavoidthesequestionstothesequestionsresearchanalysestheappearanceindicatingthedirection.Althoughusesthebestchoiceofmaterialmethodnottobeabletoavoidhavingtheproductresponsibilitylawsuit,designsthepersonnelandtheindustrycarriesonthechoiceofmaterialaccordingtothesuitableprocedure,maygreatlyreducethelawsuitthequantity.Mayseefromtheabovediscussion,thechoicematerialpeopleshouldtothematerialnature,thecharacteristicandtheprocessingmethodhavecomprehensiveandthebasicunderstanding.Finally,adesignbaseduponfunction,andaprototypemaybebuilt.Ifitstestsaresatisfactory,theinitialdesignwillundergocertainmodificationsthatenableittobemanufacturedinquantityatalowercost.Duringsubsequentyearsofmanufactureandservice,thedesignislikelytoundergochangesasnewideasareconceivedorasfurtheranalysesbasedupontestsandexperienceindicatealterations.Salesappeal.SomeRulesforDesign:Inthissectionitissuggestedthat,appliedwithacreativeattitude,analysescanleadtoimportantimprovementsandtotheconceptionandperfectionofalternate,perhapsmorefunctional,economical,anddurableproducts.Tostimulatecreativethought,thefollowingrulesaresuggestedforthedesignerandanalyst.Thefirstsixrulesareparticularlyapplicablefortheanalyst.1.Acreativeuseofneedofphysicalpropertiesandcontrolprocess.2.Recognizefunctionalloadsandtheirsignificance.3.Anticipateunintentionalloads.4.Devisemorefavorableloadingconditions.5.Provideforfavorablestressdistributionandstiffnesswithminimumweight.6.Usebasicequationstoproportionandoptimizedimensions.7.Choosematerialsforacombinationofproperties.8.Selectcarefully,stockandintegralcomponents.9.Modifyafunctionaldesigntofitthemanufacturingprocessandreducecost.10.Provideforaccuratelocationandnoninterferenceofpartsinassembly.Machinerydesigncoversthefollowingcontents.1.Providesanintroductiontothedesignprocess,problemformulation,safetyfactors.2.Reviewsthematerialpropertiesandstaticanddynamicloadinganalysis,Includingbeam,vibrationandimpactloading.3.Reviewsthefundamentalsofstressanddefectionanalysis.4.Introducesfatigue-failuretheorywiththeemphasisonstress-lifeapproachestohigh-cyclefatiguedesign,whichiscommonlyusedinthedesignofrotationmachinery.5.Discussesthoroughlythephenomenaofwearmechanisms,surfacecontactstresses,andsurfacefatigue.6.Investigatesshaftdesignusingthefatigue-analysistechniques.7.Discussesfluid-filmandrolling-elementbearingtheoryandapplication8.Givesathoroughintroductiontothekinematics,designandstressanalysisofspurgears,andasimpleintroductiontohelical,bevel,andwormgearing.9.Discussesspringdesignincludingcompression,extensionandtorsionsprings.10.Dealswithscrewsandfastenersincludingpowerscrewandpreloadfasteners.11.Introducesthedesignandspecificationofdiskanddrumclutchesandbrakes.MachineDesign:Thecompletedesignofamachineisacomplexprocess.Themachinedesignisacreativework.Projectengineernotonlymusthavethecreativityinthework,butalsomustinaspectandsoonmechanicaldrawing,kinematics,engineerigmaterial,materialsmechanicsandmachinemanufacturetechnologyhasthedeepelementaryknowledge.Oneofthefirststepsinthedesignofanyproductistoselectthematerialfromwhicheachpartistobemade.Numerousmaterialsareavailabletotodaysdesigners.Thefunctionoftheproduct,itsappearance,thecostofthematerial,andthecostoffabricationareimportantinmakingaselection.Acarefulevaluationofthepropertiesofa.materialmustbemadepriortoanycalculations.Carefulcalculationsarenecessarytoensurethevalidityofadesign.Incaseofanypartfailures,itisdesirabletoknowwhatwasdoneinoriginallydesigningthedefectivecomponents.Thecheckingofcalculations(anddrawingdimensions)isofutmostimportance.Themisplacementofonedecimalpointcanruinanotherwiseacceptableproject.Allaspectsofdesignworkshouldbecheckedandrechecked.Thecomputerisatoolhelpfultomechanicaldesignerstolightentediouscalculations,andprovideextendedanalysisofavailabledata.Interactivesystems,basedoncomputercapabilities,havemadepossibletheconceptsofcomputeraideddesign(CAD)andcomputer-aidedmanufacturing(CAM).Howdoesthepsychologistfrequentlydiscusscausesthemachinewhichthepeopleadaptsthemtooperate.Designspersonnelsbasicresponsibilityisdiligentlycausesthemachinetoadaptthepeople.Thiscertainlyisnotaneasywork,becausecertainlydoesnothavetoallpeopletosayinfactallisthemostsuperioroperatingareaandtheoperatingprocess.Anotherimportantquestion,projectengineermustbeabletocarryontheexchangeandtheconsultationwithotherconcernedpersonnel.Intheinitialstage,designsthepersonneltohavetocarryontheexchangeandtheconsultationonthepreliminarydesignwiththeadministrativepersonnel,andisapproved.Thisgenerallyisthroughtheoraldiscussion,theschematicdiagramandthewritingmaterialcarrieson.Iffrontsues,themachinedesigngoalistheproductioncanmeetthehumanneedtheproduct.Theinvention,thediscoveryandtechnicalknowledgeitselfcertainlynotnecessarilycanbringtheadvantagetothehumanity,onlyhaswhentheyareappliedcanproduceontheproductthebenefit.Thus,shouldrealizetocarriesonbeforethedesigninaspecificproduct,mustfirstdeterminewhetherthepeopledoneedthiskindofproductMustregardasthemachinedesignisthemachinedesignpersonnelcarriesonusingcreativeabilitytheproductdesign,thesystemanalysisandaformulationproductmanufacturetechnologygoodopportunity.Graspstheprojectelementaryknowledgetohavetomemorizesomedataandtheformulaismoreimportantthan.Themerelyservicedataandtheformulaisinsufficienttothecompletelydecisionwhichmakesinagooddesignneeds.Ontheotherhand,shouldbeearnestpreciselycarriesonalloperations.Forexample,evenifplaceswrongadecimalpointposition,alsocancausethecorrectdesigntoturnwrongly.Agooddesignpersonnelshoulddaretoproposethenewidea,moreoveriswillingtoundertakethecertainrisk,whenthenewmethodisnotsuitable,useoriginalmethod.Therefore,designsthepersonneltohavetohavetohavethepatience,becausespendsthetimeandtheendeavorcertainlycannotguaranteebringssuccessfully.Abrand-newdesign,therequestscreenabandonsobsoletelymany,knowsverywellthemethodforthepeople.Becausemanypersonofconservativeness,doesthiscertainlyisnotaneasymatter.Amechanicaldesignershouldunceasinglyexploretheimprovementexistingproductthemethod,shouldearnestlychooseoriginally,theprocessconfirmationprincipleofdesigninthisprocess,withhasnotunifieditaftertheconfirmationnewidea.Hereistointroducethedesignconceptofanewtypeofmixer.Theincreasingadoptionofhapticmodalityinhuman-computerinteractionparadigmshasledtoahugedemandfornewtoolsthathelpnoviceuserstoauthorandedithapticapplications.Currently,thehapticapplicationdevelopmentprocessisatimeconsumingexperiencethatrequiresprogrammingexpertise.Thecomplexityofhapticapplicationsdevelopmentrisesfromthefactthatthehapticapplicationcomponents(suchasthehapticAPI,thedevice,thehapticrenderingalgorithms,etc.)needtointeractwiththegraphiccomponentsinordertoachievesynchronicity.Additionally,thereisalackofapplicationportabilityastheapplicationistightlycoupledtoaspecificdevicethatnecessitatestheuseofitscorrespondingAPI.Therefore,deviceandAPIheterogeneityleadtothefragmentationanddisorientationofbothresearchersanddevelopers.Inviewofalltheseconsiderations,thereisaclearneedforanauthoringtoolthatcanbuildhapticapplicationswhilehidingprogrammingdetailsfromtheapplicationmodeler(suchasAPI,device,orvirtualmodel).TheBlenderdesignphilosophyisbasedonthreemaintasks:datastorage,editing,andvisualization.Itfollowsadata-visualize-editdevelopmentcycleforthe3Dmodelingpipeline.A3DsceneisrepresentedusingdatastructureswithintheBlenderarchitecture.Themodelerviewsthescene,makeschangesusingtheeditinginterfacewhichdirectlymodifiestheunderlyingdatastructures,andthenthecyclerepeats.Tobetterunderstandthisdevelopmentcycle,considertherepresentationofa3DobjectinBlender.A3Dobjectmayberepresentedbyanarrayofverticeswhichhavebeenorganizedasapolygonalmesh.Usersmaychoosetooperateonanysubsetofthisdataset.Editingtasksmayincludeoperationstorotate,scale,andtranslatethevertices,orperhapsare-meshingalgorithmto"cleanup"redundantverticesandtransformfromaquadtoatriangletopology.Thedataisvisualizedusingagraphical3Drendererwhichiscapableofdisplayingtheobjectasawireframeorasashaded,solidsurface.Thevisualizationisnecessaryinordertoseetheeffectsofeditingonthedata.Inanutshell,thisexampledefinesthedesignphilosophybehindBlendersarchitecture.InBlender,dataisorganizedasaseriesoflistsandbasedatatypesarecombinedwithlinksbetweenitemsineachlist,creatingcomplexscenesfromsimplestructures.Thisallowsdataelementsineachlisttobereused,thusreducingtheoverallstoragerequirements.Forexample,ameshmaybelinkedbymultiplesceneobjects,butthepositionandorientationmaychangeforeachobjectandthetopologyofthemeshremainsthesame.Themeshesalsoshareacommonmaterialproperty.Theentiresceneisrenderedononeofseveralscreens,whichvisualizesthescene.WeadopttheBlenderdesignapproachforourauthoringtool.Thedatastructureswhichareusedtorepresentobjectsina3Dscenehavebeenaugmentedtoincludefieldsforhapticproperties(e.g.,stiffness,damping)；userinterfacecomponents(e.g.,buttonpanels)whichallowthemodelertochangeobjectpropertieshavealsobeenupdatedtoincludesupportformodifyingthehapticpropertiesofanobject.Additionally,aninteractivehapto-visualrendererhasbeenimplementedtodisplaythe3Dscenegraphicallyandhaptically,providingthemodelerorartistwithimmediatefeedbackaboutthechangestheymaketothescene.inthecurrentversionoftheHAMLAT.themodificationstotheBlenderframeworkinclude:datastructuresforrepresentinghapticproperties,aneditinginterfaceformodifyinghapticproperties,anexternalrendererfordisplayingandpreviewinghapticallyenabledscenes,scriptswhichallowscenestobeimported/exportedintheHAMLfileformat.AclassdiagramoutliningthechangestotheBlenderrameworkisshown.ComponentswhichareertinenttoHAMLATareshadedingray.HAMLATbuildsonexistingBlendersub-systemsbyextendingthemorhapticmodelingpurposes.Datastructuresforrepresentingobjectgeometryandgraphicalrenderingareaugmentedtoincludefieldwhichencompassthetactilepropertiesnecessaryforhapticrendering.ToallowtheusertomodifyhapticpropertiesGUIComponentsareintegratedaspartoftheBlendereditingpanels.TheoperationstriggeredbythesecomponentsoperatedirectlyonthedatastructuresusedforrepresentinghaticcuesandmaybeconsideredpartoftheeditingstepoftheBlenderdesigncycle.Similarlytothebuilt-ingraphicalrenderer,HAMLATusesacustomrendlererfordisplaying3Dsscenesgrphcalandhaptcall,anisineednoftheBlenderrenderer.Thiscomponentisdevelopedindependentlysincehapticalandgraphicalrenderingmustbeperformedsimultaneouslyandsynchronously.Asimulationloopisusedtoupdatehapticrenderingforcesataratewhichmaintainsstabilityandquality.Adetaileddiscussionoftheimplementationoftheseclassesandtheirconnectivityisgiveninthenextsection.IIIIMLIEMENTATIONADataStructureA.1MeshDataTypeBlenderusesmanydifferentdatastructurestorepresentthevarioustypesofobjectsina3Dsceneavertices；alampcontainscolourandintensityvalues；andcameraaobjectcontainsintrinsicviewingparameters.TheMeshdatastructureiSusedbytheBlenderinframeworktodescribeapolygonalmeshobject.ItiSofparticularinterestforhapicrenderingsincemanysolidobjectsina3Dscenemayberepresentedusingthistypeofdatastructure.Thetactileandkinestheticcues,whicharedisplayedduetointeractionwithvirtualobjects,aretypicallyrenderedbasedonthegeometryofthemesh.Hpticrenderingisperformedbasedprimaryondatastoredinthisdatatype.Otherscenecomponentssuchaslamps,cameras,orlinesarenotintuitivelyrenderedusingforcefeedbackhapticdevicesandarethereforenotofcurrentinterestforhapticrendering.AnaugmentedversionoftheMeshdatastructureisshown.Itcontainsfieldsforvertexandfacedata,plussomespecialcustomdatafieldswhichallowdatatobestoredto/retrievedfromdiskandmemory.WehavemodifiedthisdatatypetoincludeapointertoaMHapticsdatastructure,whichstoreshapticpropertiessuchasstiffness,damping,andfrictionforthemeshelements.A.2EditMeshDataTypeItshouldbenotedthattheMeshdatatypehasacomPlimentarydatastructure,calledEditMesh,whichisusedwheneditingmeshdata.Itholdsacopyofthevertex,edge,andfacedataforapolygonalmesh.whentheuserswitchestoeditingmode,theBlendercopiesthedatafromaMeshintoanEditMeshandwheneditingiscompletethedataiscopiedback.Caremustbetakentoensurethatthehapicpropertydatastructureremainsintactduringthecopysequence.TheEditMeshdatastructurehasnotbeenmodifiedtocontainacopyofthehapicpropertydata,butthismaypropertiesineditmodeisrequired).Theeditingmodeismainlyusedtomodifymeshtopologyandgeometry,notthehapticandgraphicalrenderingcharacteristics,A.3HapticPropertiesInthissectionwellbrieflydiscussthehapticpropertieswhichmaycurrentlybemodeledusing