站内搜索

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

外文翻译输送带的二维动态特性.doc外文翻译输送带的二维动态特性.doc

收藏

编号:201311171436006619    类型:共享资源    大小:283.05KB    格式:DOC    上传时间:2013-11-17
  
5
关 键 词:
专业文献 学术论文 精品文档 外文翻译
资源描述:
TheTwo-DimensionalDynamicBehaviorofConveyorBeltsIr.G.Lodewijks,DelftUniversityofTechnology,TheNetherlands1.SUMMARY1--------Inthispaperanewfiniteelementmodelofabelt-conveyorsystemwillbeintroduced.Thismodelhasbeendevelopedinordertobeabletosimulateboththelongitudinalandtransversedynamicresponseofthebeltduringstartingandstopping.Applicationofthemodelinthedesignstageoflongoverlandbelt-conveyorsystemsenablestheengineer,forexample,todesignproperbelt-conveyorcurvesbydetectingprematureliftingofthebeltofftheidlers.Italsoenablesthedesignofoptimalidlerspacingandtroughingconfigurationinordertoensureresonancefreebeltmotionbydetermining(standing)longitudinalandtransversebeltvibrations.Applicationoffeed-backcontroltechniquesenablesthedesignofoptimalstartingandstoppingprocedureswhereasanoptimalbeltcanbeselectedbytakingthedynamicpropertiesofthebeltintoaccount.2.INTRODUCTION2--------TheNetherlandshaslongbeenrecognisedasacountryinwhichtransportandtranshipmentplayamajorroleintheeconomy.TheportofRotterdam,inparticularisknownasthegatewaytoEuropeandclaimstohavethelargestharboursystemintheworld.Besidesthelargenumbersofcontainers,alargevolumeofbulkgoodsalsopassesthroughthisport.NotallthesegoodsareintendedfortheDutchmarket,manyhaveotherdestinationsandaretranshippedinRotterdam.Goodexamplesoftypicalbulkgoodsthataretranshippedarecoalandironore,asignificantpartofwhichisintendedfortheGermanmarket.Inordertohandlethebulkmaterialsawiderangeofdifferentmechanicalconveyorsincludingbelt-conveyorsisused.3--------Thelengthofmostbelt-conveyorsystemserectedintheNetherlandsisrelativelysmall,sincetheyaremainlyusedforin-plantmovementofbulkmaterials.Thelongestbelt-conveyorsystem,whichisabout2kmlong,issituatedontheMaasvlakte,partoftheportofRotterdam,whereitisusedtotransportcoalfromabulkterminaltoanelectricitypowerstation.Inadditiontodomesticprojects,anincreasingnumberofDutchengineeringconsultanciesparticipatesininternationalprojectsforthedevelopmentoflargeoverlandbelt-conveyorsystems.Thisdemandstheunderstandingoftypicaldifficultiesencounteredduringthedevelopmentofthesesystems,whicharestudiedintheDepartmentofTransportTechnologyoftheFacultyofMechanicalEngineering,DelftUniversityofTechnology,oneofthethreeDutchUniversitiesofTechnology.4--------Theinteractionbetweentheconveyorbeltproperties,thebulksolidsproperties,thebeltconveyorconfigurationandtheenvironmentallinfluencetheleveltowhichtheconveyor-systemmeetsitspredefinedrequirements.Someinteractionscausetroublesomephenomenasoresearchisinitiatedintothosephenomenawhichcausepracticalproblems,[1].Onewaytoclassifytheseproblemsistodividethemintothecategorywhichindicatetheirunderlyingcausesinrelationtothedescriptionofbeltconveyors.5---------Thetwomostimportantdynamicconsiderationsinthedescriptionofbeltconveyorsarethereductionoftransientstressesinnon-stationarymovingbeltsandthedesignofbelt-conveyorlay-outsforresonance-freeoperation,[2].Inthispaperanewfiniteelementmodelofabelt-conveyorsystemwillbepresentedwhichenablesthesimulationofthebelt'slongitudinalandtransverseresponsetostartingandstoppingproceduresandit'smotionduringsteadystateoperation.It'sbeyondthescopeofthispapertodiscusstheresultsofthesimulationofastart-upprocedureofabelt-conveyorsystem,thereforeanexamplewillbegivenwhichshowsomepossibilitiesofthemodel。3.FINITEELEMENTMODELSOFBELT-CONVEYORSYSTEMS6--------Ifthetotalpowersupply,neededtodriveabelt-conveyorsystem,iscalculatedwithdesignstandardslikeDIN22101thenthebeltisassumedtobeaninextensiblebody.ThisimpliesthattheforcesexertedonthebeltduringstartingandstoppingcanbederivedfromNewtonianrigidbodydynamicswhichyieldsthebeltstress.Withthisbeltstressthemaximumextensionofthebeltcanbecalculated.Thiswayofdeterminingtheelasticresponseofthebeltiscalledthequasi-static(design)approach.Forsmallbelt-conveyorsystemsthisleadstoanacceptabledesignandacceptableoperationalbehaviorofthebelt.Forlongbelt-conveyorsystems,however,thismayleadtoapoordesign,highmaintenancecosts,shortconveyor-componentlifeandwellknownoperationalproblemslike:excessivelargedisplacementoftheweightofthegravitytake-updeviceprematurecollapseofthebelt,mostlyduetothefailureofthesplicesdestructionofthepulleysandmajordamageoftheidlersliftingofthebeltofftheidlerswhichcanresultinspillageofbulkmaterialdamageandmalfunctioningof(hydrokinetic)drivesystemsManyresearchersdevelopedmodelsinwhichtheelasticresponseofthebeltistakenintoaccountinordertodeterminethephenomenaresponsiblefortheseproblems.Inmostmodelsthebelt-conveyormodelconsistsoffiniteelementsinordertoaccountforthevariationsoftheresistance'sandforcesexertedonthebelt.Theglobalelasticresponseofthebeltismadeupbytheelasticresponseofallitselements.Thesefiniteelementmodelshavebeenappliedincomputersoftwarewhichcanbeusedinthedesignstageoflongbelt-conveyorsystems.Thisiscalledthedynamic(design)approach.Verificationoftheresultsofsimulationhasshownthatsoftwareprogramsbasedonthesekindofbelt-modelsarequitesuccessfulinpredictingtheelasticresponseofthebeltduringstartingandstopping,seeforexample[3]and[4].Thefiniteelementmodelsasmentionedabovedetermineonlythelongitudinalelasticresponseofthebelt.Thereforetheyfailintheaccuratedeterminationof:themotionofthebeltovertheidlersandthepulleysthedynamicdrivephenomenathebendingresistanceofthebeltthedevelopmentof(shock)stresswavestheinteractionbetweenthebeltsagandthepropagationoflongitudinalstresswavestheinteractionbetweentheidlerandthebelttheinfluenceofthebeltspeedonthestabilityofmotionofthebeltthedynamicstressesinthebeltduring.passageofthebeltovera(driven)pulleytheinfluenceofparametricresonanceofthebeltduetotheinteractionbetweenvibrationsofthetakeupmassoreccentricitiesoftheidlersandthetransversedisplacementsofthebeltthedevelopmentofstandingtransversewavestheinfluenceofthedampingcausedbybulkmaterialandbythedeformationofthecross-sectionalareaofthebeltandbulkmaterialduring,passageofanidlertheliftingofthebeltofftheidlersinconvexandconcavecurvesThetransverseelasticresponseofthebeltisoftenthecauseofbreakdownsinlongbelt-conveyorsystemsandshouldthereforebetakenintoaccount.Thetransverseresponseofabeltcanbedeterminedwithspecialmodelsasproposedin[5]and[6],butitismoreconvenienttoextendthepresentfiniteelementmodelswithspecialelementswhichtakethisresponseintoaccount.3.1THEBELTAtypicalbelt-conveyorgeometryconsistingofadrivepulley,atailpulley,averticalgravitytake-up,anumberofidlersandaplatesupportisshowninFigure1.Thisgeometryistakenasanexampletoillustratehowafiniteelementmodelofabeltconveyorcanbedevelopedwhenonlythelongitudinalelasticresponseofthebeltisofinterest.Sincethelengthofthebeltpartbetweenthedrivepulleyandthetake-uppulley,Is,isnegligiblecomparedtothelengthofthetotalbelt,L,thesepulleyscanmathematicallybecombinedtoonepulleyaslongasthemassinertia'softhepulleysofthetake-upsystemareaccountedfor.Sincetheresistanceforcesencounteredbythebeltduringmotionvaryfromplacetoplacedependingontheexactlocal(maintenance)conditionsandgeometryofthebeltconveyor,theseforcesaredistributedalongthelengthofthebelt.Inordertobeabletodeterminetheinfluenceofthesedistributedforcesonthemotionofthebelt,thebeltisdividedintoanumberoffiniteelementsandtheforceswhichactonthatspecificpartofthebeltareallocatedtothecorresponding,element.Iftheinterestisinthelongitudinalelasticresponseofthebeltonlythenthebeltisnotdiscreditedonthoseplaceswhereitissupportedbyapulleywhichdoesnotforceitsmotion(slippossible).Thelaststepinbuilding,themodelistoreplacethebelt'sdriveandtensioningsystembytwoforceswhichrepresentthedrivecharacteristicandthetensionforces.Theexactinterpretationofthefiniteelementsdependsonwhichresistance'sandinfluencesoftheinteractionbetweenthebeltanditssupportingstructurearetakenintoaccountandthemathematicaldescriptionoftheconstitutivebehaviorofthebeltmaterial.Dependingonthisinterpretation,theelementscanberepresentedbyasystemofmasses,springsanddashpotsasisshowninFigure1,[9],wheresuchasystemisgivenforonefiniteelementwithnodalpointscandc+1.ThespringsKanddashpotHrepresentthevisco-elasticbehaviorofthebelt'stensilemember,Grepresentsthebelt'svariablelongitudinalgeometricstiffnessproducedbytheverticalactingforcesonthebelt'scrosssectionbetweentwoidlers,Vrepresentthebeltsvelocitydependentresistance's.Figure1:Fiveelementcompositemodel[9].3.1.1NONLINEARTRUSSELEMENTIfonlythelongitudinaldeformationofthebeltisofinterestthenatrusselementcanbeusedtomodeltheelasticresponseofthebelt.AtrusselementasshowninFigure2hastwonodalpoints,pandq,andfourdisplacementparameterswhichdeterminethecomponentvectorx:
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
关于本文
本文标题:外文翻译输送带的二维动态特性.doc
链接地址:http://www.renrendoc.com/p-96619.html

当前资源信息

4.0
 
(2人评价)
浏览:29次
淘宝运营上传于2013-11-17

官方联系方式

客服手机:17625900360   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

精品推荐

相关阅读

关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

网站客服QQ:2846424093    人人文库上传用户QQ群:460291265   

[email protected] 2016-2018  renrendoc.com 网站版权所有   南天在线技术支持

经营许可证编号:苏ICP备12009002号-5