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

外文翻译输送带的二维动态特性.doc

  • 资源星级:
  • 资源大小:283.05KB   全文页数:27页
  • 资源格式: DOC        下载权限:注册会员
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   

外文翻译输送带的二维动态特性.doc

TheTwoDimensionalDynamicBehaviorofConveyorBeltsIr.G.Lodewijks,DelftUniversityofTechnology,TheNetherlands1.SUMMARY1Inthispaperanewfiniteelementmodelofabeltconveyorsystemwillbeintroduced.Thismodelhasbeendevelopedinordertobeabletosimulateboththelongitudinalandtransversedynamicresponseofthebeltduringstartingandstopping.Applicationofthemodelinthedesignstageoflongoverlandbeltconveyorsystemsenablestheengineer,forexample,todesignproperbeltconveyorcurvesbydetectingprematureliftingofthebeltofftheidlers.Italsoenablesthedesignofoptimalidlerspacingandtroughingconfigurationinordertoensureresonancefreebeltmotionbydeterminingstandinglongitudinalandtransversebeltvibrations.Applicationoffeedbackcontroltechniquesenablesthedesignofoptimalstartingandstoppingprocedureswhereasanoptimalbeltcanbeselectedbytakingthedynamicpropertiesofthebeltintoaccount.2.INTRODUCTION2TheNetherlandshaslongbeenrecognisedasacountryinwhichtransportandtranshipmentplayamajorroleintheeconomy.TheportofRotterdam,inparticularisknownasthegatewaytoEuropeandclaimstohavethelargestharboursystemintheworld.Besidesthelargenumbersofcontainers,alargevolumeofbulkgoodsalsopassesthroughthisport.NotallthesegoodsareintendedfortheDutchmarket,manyhaveotherdestinationsandaretranshippedinRotterdam.Goodexamplesoftypicalbulkgoodsthataretranshippedarecoalandironore,asignificantpartofwhichisintendedfortheGermanmarket.Inordertohandlethebulkmaterialsawiderangeofdifferentmechanicalconveyorsincludingbeltconveyorsisused.3ThelengthofmostbeltconveyorsystemserectedintheNetherlandsisrelativelysmall,sincetheyaremainlyusedforinplantmovementofbulkmaterials.Thelongestbeltconveyorsystem,whichisabout2kmlong,issituatedontheMaasvlakte,partoftheportofRotterdam,whereitisusedtotransportcoalfromabulkterminaltoanelectricitypowerstation.Inadditiontodomesticprojects,anincreasingnumberofDutchengineeringconsultanciesparticipatesininternationalprojectsforthedevelopmentoflargeoverlandbeltconveyorsystems.Thisdemandstheunderstandingoftypicaldifficultiesencounteredduringthedevelopmentofthesesystems,whicharestudiedintheDepartmentofTransportTechnologyoftheFacultyofMechanicalEngineering,DelftUniversityofTechnology,oneofthethreeDutchUniversitiesofTechnology.4Theinteractionbetweentheconveyorbeltproperties,thebulksolidsproperties,thebeltconveyorconfigurationandtheenvironmentallinfluencetheleveltowhichtheconveyorsystemmeetsitspredefinedrequirements.Someinteractionscausetroublesomephenomenasoresearchisinitiatedintothosephenomenawhichcausepracticalproblems,1.Onewaytoclassifytheseproblemsistodividethemintothecategorywhichindicatetheirunderlyingcausesinrelationtothedescriptionofbeltconveyors.5Thetwomostimportantdynamicconsiderationsinthedescriptionofbeltconveyorsarethereductionoftransientstressesinnonstationarymovingbeltsandthedesignofbeltconveyorlayoutsforresonancefreeoperation,2.Inthispaperanewfiniteelementmodelofabeltconveyorsystemwillbepresentedwhichenablesthesimulationofthebeltslongitudinalandtransverseresponsetostartingandstoppingproceduresanditsmotionduringsteadystateoperation.Itsbeyondthescopeofthispapertodiscusstheresultsofthesimulationofastartupprocedureofabeltconveyorsystem,thereforeanexamplewillbegivenwhichshowsomepossibilitiesofthemodel。3.FINITEELEMENTMODELSOFBELTCONVEYORSYSTEMS6Ifthetotalpowersupply,neededtodriveabeltconveyorsystem,iscalculatedwithdesignstandardslikeDIN22101thenthebeltisassumedtobeaninextensiblebody.ThisimpliesthattheforcesexertedonthebeltduringstartingandstoppingcanbederivedfromNewtonianrigidbodydynamicswhichyieldsthebeltstress.Withthisbeltstressthemaximumextensionofthebeltcanbecalculated.Thiswayofdeterminingtheelasticresponseofthebeltiscalledthequasistaticdesignapproach.Forsmallbeltconveyorsystemsthisleadstoanacceptabledesignandacceptableoperationalbehaviorofthebelt.Forlongbeltconveyorsystems,however,thismayleadtoapoordesign,highmaintenancecosts,shortconveyorcomponentlifeandwellknownoperationalproblemslikeexcessivelargedisplacementoftheweightofthegravitytakeupdeviceprematurecollapseofthebelt,mostlyduetothefailureofthesplicesdestructionofthepulleysandmajordamageoftheidlersliftingofthebeltofftheidlerswhichcanresultinspillageofbulkmaterialdamageandmalfunctioningofhydrokineticdrivesystemsManyresearchersdevelopedmodelsinwhichtheelasticresponseofthebeltistakenintoaccountinordertodeterminethephenomenaresponsiblefortheseproblems.Inmostmodelsthebeltconveyormodelconsistsoffiniteelementsinordertoaccountforthevariationsoftheresistancesandforcesexertedonthebelt.Theglobalelasticresponseofthebeltismadeupbytheelasticresponseofallitselements.Thesefiniteelementmodelshavebeenappliedincomputersoftwarewhichcanbeusedinthedesignstageoflongbeltconveyorsystems.Thisiscalledthedynamicdesignapproach.Verificationoftheresultsofsimulationhasshownthatsoftwareprogramsbasedonthesekindofbeltmodelsarequitesuccessfulinpredictingtheelasticresponseofthebeltduringstartingandstopping,seeforexample3and4.Thefiniteelementmodelsasmentionedabovedetermineonlythelongitudinalelasticresponseofthebelt.Thereforetheyfailintheaccuratedeterminationofthemotionofthebeltovertheidlersandthepulleysthedynamicdrivephenomenathebendingresistanceofthebeltthedevelopmentofshockstresswavestheinteractionbetweenthebeltsagandthepropagationoflongitudinalstresswavestheinteractionbetweentheidlerandthebelttheinfluenceofthebeltspeedonthestabilityofmotionofthebeltthedynamicstressesinthebeltduring.passageofthebeltoveradrivenpulleytheinfluenceofparametricresonanceofthebeltduetotheinteractionbetweenvibrationsofthetakeupmassoreccentricitiesoftheidlersandthetransversedisplacementsofthebeltthedevelopmentofstandingtransversewavestheinfluenceofthedampingcausedbybulkmaterialandbythedeformationofthecrosssectionalareaofthebeltandbulkmaterialduring,passageofanidlertheliftingofthebeltofftheidlersinconvexandconcavecurvesThetransverseelasticresponseofthebeltisoftenthecauseofbreakdownsinlongbeltconveyorsystemsandshouldthereforebetakenintoaccount.Thetransverseresponseofabeltcanbedeterminedwithspecialmodelsasproposedin5and6,butitismoreconvenienttoextendthepresentfiniteelementmodelswithspecialelementswhichtakethisresponseintoaccount.3.1THEBELTAtypicalbeltconveyorgeometryconsistingofadrivepulley,atailpulley,averticalgravitytakeup,anumberofidlersandaplatesupportisshowninFigure1.Thisgeometryistakenasanexampletoillustratehowafiniteelementmodelofabeltconveyorcanbedevelopedwhenonlythelongitudinalelasticresponseofthebeltisofinterest.Sincethelengthofthebeltpartbetweenthedrivepulleyandthetakeuppulley,Is,isnegligiblecomparedtothelengthofthetotalbelt,L,thesepulleyscanmathematicallybecombinedtoonepulleyaslongasthemassinertiasofthepulleysofthetakeupsystemareaccountedfor.Sincetheresistanceforcesencounteredbythebeltduringmotionvaryfromplacetoplacedependingontheexactlocalmaintenanceconditionsandgeometryofthebeltconveyor,theseforcesaredistributedalongthelengthofthebelt.Inordertobeabletodeterminetheinfluenceofthesedistributedforcesonthemotionofthebelt,thebeltisdividedintoanumberoffiniteelementsandtheforceswhichactonthatspecificpartofthebeltareallocatedtothecorresponding,element.Iftheinterestisinthelongitudinalelasticresponseofthebeltonlythenthebeltisnotdiscreditedonthoseplaceswhereitissupportedbyapulleywhichdoesnotforceitsmotionslippossible.Thelaststepinbuilding,themodelistoreplacethebeltsdriveandtensioningsystembytwoforceswhichrepresentthedrivecharacteristicandthetensionforces.Theexactinterpretationofthefiniteelementsdependsonwhichresistancesandinfluencesoftheinteractionbetweenthebeltanditssupportingstructurearetakenintoaccountandthemathematicaldescriptionoftheconstitutivebehaviorofthebeltmaterial.Dependingonthisinterpretation,theelementscanberepresentedbyasystemofmasses,springsanddashpotsasisshowninFigure1,9,wheresuchasystemisgivenforonefiniteelementwithnodalpointscandc1.ThespringsKanddashpotHrepresenttheviscoelasticbehaviorofthebeltstensilemember,Grepresentsthebeltsvariablelongitudinalgeometricstiffnessproducedbytheverticalactingforcesonthebeltscrosssectionbetweentwoidlers,Vrepresentthebeltsvelocitydependentresistances.Figure1Fiveelementcompositemodel9.3.1.1NONLINEARTRUSSELEMENTIfonlythelongitudinaldeformationofthebeltisofinterestthenatrusselementcanbeusedtomodeltheelasticresponseofthebelt.AtrusselementasshowninFigure2hastwonodalpoints,pandq,andfourdisplacementparameterswhichdeterminethecomponentvectorx

注意事项

本文(外文翻译输送带的二维动态特性.doc)为本站会员(淘宝运营)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