会员注册 | 登录 | 微信快捷登录 支付宝快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

   首页 人人文库网 > 资源分类 > DOC文档下载

外文翻译--新型凸轮轮廓优化.doc

  • 资源星级:
  • 资源大小:288.00KB   全文页数:6页
  • 资源格式: DOC        下载权限:注册会员/VIP会员
您还没有登陆,请先登录。登陆后即可下载此文档。
  合作网站登录: 微信快捷登录 支付宝快捷登录   QQ登录   微博登录
友情提示
2:本站资源不支持迅雷下载,请使用浏览器直接下载(不支持QQ浏览器)
3:本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰   

外文翻译--新型凸轮轮廓优化.doc

宁波大红鹰学院毕业设计(论文)外文翻译所在学院机电学院班级姓名学号指导教师合作导师2012年12月16日原文题目CamprofileoptimizationforanewcamdriveAbstractAcomplexcamshapeoptimizationproblemisstudiedtooptimizeauniquecammechanismforanewcamdriveengine.First,theoptimizationproblemisdefinedthroughanalyzingtheuniquecammechanism.Multipledesignspecificationsareincludedintheoptimizationproblembydefiningtheoutputtorqueoftheengineastheobjectivefunctionandthecontactstress,radiusofcurvature,andpressureangleastheconstraints.Second,ananalyticalscenarioisdesignedtofindthebestevercamprofilesthroughmanipulatingthedifferentcombinationsofcamprofilerepresentationsandoptimizationmethods.Twotypesofcurverepresentations,includinggeneralpolynomialsplineandBspline,areemployedincamprofilesynthesis.Inaddition,bothaclassicaloptimizationtechniqueandageneticalgorithmGAbasedmethodareappliedtosolvethecomplexoptimizationproblem.Finally,comparativestudiesareperformedamongtheinitialprofileandtheoptimalprofilestodemonstratetheeffectivenessoftheseproposeddesignapproachesonsolvingthecamprofileoptimizationproblem.ResultsshowthatthebestprofilesareobtainedfromacombinationoftheBsplinerepresentationandtheGAbasedmethod.Inaddition,comparedtotheinitialdesign,theengineperformanceisimprovedgreatlybytheproposedoptimizationapproaches.Platecammechanismisawidelyusedmachinecomponentwiththecontinuouscontactmotionofcamandfollower,andcaneasilyproduceanyfunctionalmotionoffollowerduetotherotationofcam.Cammechanismhasthediversetypesbythecombinationofdifferentshapeofcamandmotionoffollowerplateorcylindricalcam,rollerorflatfacedfollower,andreciprocatingoroscillatingmotion.Inspiteoftheadvantagesofafewnumberoflinks,simplestructure,positivemotion,andcompactsize,cammechanismsrequiretheaccurateshapedesignandprecisemachiningproceduresforsatisfyingthemechanicalrequirements.Underthelowleveleddesignandmanufacturing,cammechanismsgivetheheavyeffectsonvibration,noise,separation,andoverloadingtoanoverallsystem.Toavoidtheseeffects,cammechanismmustbewelldesignedaccuratelyandmachinedprecisely.Actually,ahybridCAD/CAMapproachmaybethebestsolutionthattheshapedatafromthedesignprocessaredirectlycombinedtothemachiningdataforthemanufacturingprocessAsaninnovationofreplacingtheconventionalcrankshaft/connectingrodmechanismbycammechanisminenginedesign,anewtypeofenginecalledthecamdriveengineisbeingdevelopedinafewplacesintheworld.Thecamdriveenginehasuniquefeaturesovertheconventionalengines,amongwhichthecamdriveisthemostprominentone.Forcamdrive,thecamprofilescontroltheengineoperationstrokesbydeterminingthetimingofvariousintakeandexhaustevents.Moreover,theuseofcamdrivefacilitateshavingaseparatecompressionratioandexpansionratio,aseparationthatismuchmoredifficulttoaccomplishwiththeprevalentcrankshaft/connectingrodenginedesign.Thenewtypeofengineisbelievedtohavemajoradvantagesovertheconventionalengines,includinghigherpower,betterfueleconomy,smootheroperation,higherreliability,andlighterweight.Theapplicationofthecammechanismtocamdriveenginemakesthedesignofthecamprofilesessentialtotheoverallengineperformance.However,theinitialcamprofilesweredesignedusingatraditionalcamdesignapproach.Forthesocalledtrialanderrorapproach,thecamprofilesarefirstgeneratedtomeetthegeometryspecificationssuchasthespecifiedvaluesofdisplacement,velocity,andaccelerationatdifferentengineevents,andthenthefeasibilityofthegeneratedcamprofilesischeckedtomeettheotherdesignspecifications,includingtheoutputtorqueoftheengine,radiusofcurvature,andpressureangle,etc..Althoughthisapproachissimpleinprinciple,itsdisadvantagesareobvious.First,thisapproachisnotefficient.Ithastobeappliedmanytimesinordertoachieveasatisfactoryengineperformance.Therefore,itresultsinalaboriousandtimeconsumingdesignprocess.Moreover,sincethecamdesignprobleminvolvesthedeterminationoftheprofilesofbothintakecamandexhaustcam,theinterplaysofthetwoprofilesaddmorecomplexitytothetrialanderrorapproach.Finally,althoughtheresultfoundbythisapproachisfeasible,itisveryunlikelytobeoptimal.Therefore,itisnecessarytouseanoptimaldesignapproach,inconjunctionwithanappropriatecamprofilerepresentation,todeterminethemostsuitablecamprofilesofbothintakecamandexhaustcaminordertomeetthemultipledesignspecifications.Thisisthemotivationoftheproposedresearch.Tothisend,wefirstreviewthepreviousresearchoncamdesignandoptimizationasfollows.Thecamdesignhaschangeddramaticallyoverthepastdecadesbytakingadvantageofthetremendousadvanceincomputingdevicesandmathematicstools,especiallythesplines.Theimpetusforthechangeisthedemandforcamswithhigherspeeds,smootheroperation,andbetterperformance.Theresearchactivitiesoncamdesigncanbeclassifiedintotwocategoriesaccordingtothecurverepresentationofcamprofilepolynomialbasedmethodsandsplinebasedmethods.Inthereviewofthepaststudiesoncamdesignandoptimization,weaddressthefollowingthreeaspectsinthisresearch.First,themultipledesignspecificationsforthecamdriveengineareconsideredintheoptimizationproblem.Weselecttheoutputtorqueataspecifiedenginespeedastheobjectivefunction.Inaddition,theotherimportantdesignspecifications,includingcontactstress,radiusofcurvature,andpressureangle,areconsideredastheconstraintsintheoptimizationproblem.Themajordifferenceoftheproposedresearchfromtypicalcamprofileoptimizationisthattheoutputtorqueisselectedastheobjectivefunctioninsteadoftheresidualvibrations.ThereasonisthatthepresenceofresidualvibrationsisnotprominentbecausethefollowerSeeFig.1isdesignedtohaveenoughrigidityinthecamfollowermechanism.Incontrast,theoutputtorqueataspecifiedenginespeedisoneofthemajorconcernsfromtheenginedesignaspect.Thechoiceoftheoutputtorqueastheobjectivefunctionprovidesmultidisciplinaryaspectstotheproposedresearch,inwhichbothcamdesignandenginedesignareincluded.Second,insteadofstudyingonlyonecaminthepaststudies,theproposedresearchaimstooptimizeintakecamandexhaustcamsimultaneouslytomakethecamfollowermechanismfulfillappropriatelythedifferentengineeventsduringthewholeenginecycle.Thecomplexityoftheoptimizationproblemincreasesaccordinglysincebothcamsaredesignedintheoptimizationproblem.Finally,tostudycomprehensivelytheoptimizationproblem,ananalyticalscenarioisdesignedtoinvestigatehowtheoptimizationresultsareaffectedbydifferentcombinationsofcamprofilerepresentationsandoptimizationmethods.Acomplexcamprofileoptimizationproblemhasbeeninvestigatedforauniquecammechanisminanewcamdriveengine.First,theoptimizationproblemhasbeendefinedbytakingintoaccountmultipledesignspecifications.Theoutputtorqueoftheengineisconsideredastheobjectivefunction.Inaddition,theotherdesignspecifications,includingthecontactstress,thepressureangle,andtheradiusofcurvature,areselectedastheconstraints.Second,ananalyticalscenariohasbeendesignedtoinvestigatehowtheoptimizationresultsareaffectedbydifferentcombinationsofcamprofilerepresentationsandoptimizationmethods.Tothisend,twotypesofcurverepresentations,i.e.,generalpolynomialsplineandBspline,havebeenusedincamprofilesynthesis.Moreover,bothaclassicaloptimizationtechniqueandageneticalgorithmGAbasedmethodhavebeenappliedtosolvetheoptimizationproblem.Finally,aseriesofcomparativestudieshavebeenperformedamongtheinitialdesignandtheoptimaldesignofthecamprofiles.Threesetsoftheoptimalprofileshavebeengeneratedthroughmanipulatingdifferentcombinationsofthecamprofilerepresentationsandtheoptimizationmethods.ResultsshowthatthebestprofilesareobtainedfromthecombinationoftheBsplinerepresentationandtheGAbasedmethod.Thebestprofilesprovidebetterresultsintermsoftheoutputtorqueandthesmoothnessvalue,comparedtotheothertwosetsofoptimalprofiles.Moreover,theoutputtorquegeneratedbythebestprofilesincreasesby28comparedtothatgeneratedbytheinitialprofiles.

注意事项

本文(外文翻译--新型凸轮轮廓优化.doc)为本站会员(英文资料库)主动上传,人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知人人文库网([email protected]),我们立即给予删除!

温馨提示:如果因为网速或其他原因下载失败请重新下载,重复下载不扣分。

copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5