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外文翻译---龙门式起重机金属材料的疲劳强度预测.doc

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外文翻译---龙门式起重机金属材料的疲劳强度预测.doc

附录A英文原文FatiguelifepredictionofthemetalworkofatravellinggantrycraneV.A.KopnovP.O.Box64,Eknteriuburg620107,RussianReceived3April1998accepted29September1998AbstractIntrinsicfatiguecurvesareappliedtoafatiguelifepredictionproblemofthemetalworkofatravelinggantrycrane.Acrane,usedintheforestindustry,wasstudiedinworkingconditionsatalogyard,anstrainmeasurementsweremade.Forthecalculationsofthenumberofloadingcycles,therainflowcyclecountingtechniqueisused.Theoperationsofasampleofsuchcraneswereobservedforayearfortheaveragenumberofoperationcyclestobeobtained.Thefatiguefailureanalysishasshownthatfailuressomeelementsaresystematicinnatureandcannotbeexplainedbyrandomcauses.卯1999ElsevierScienceLtd.Allrightsreserved.KeywordsCranesFatigueassessmentStraingauging1.IntroductionFatiguefailuresofelementsofthemetalworkoftravelinggantrycranesLT62Bareobservedfrequentlyinoperation.Failuresasfatiguecracksinitiateandpropagateinweldedjointsofthecranebridgeandsupportsinthreefouryears.Suchcranesareusedintheforestindustryatlogyardsfortransferringfulllengthandsawnlogstoroadtrains,havingaloadfittingcapacityof32tons.Morethan1000cranesofthistypeworkattheenterprisesoftheRussianforestindustry.Theproblemwasstatedtofindtheweakestelementslimitingthecranesfives,predicttheirfatiguebehavior,andgiverecommendationstothemanufacturersforenhancingthefivesofthecranes.2.AnalysisofthecraneoperationFortheanalysis,atravelinggantrycraneLT62BinstalledatlogyardintheYekaterinburgregionwaschosen.Thecraneservestwosawmills,createsalogstore,andtransferslogstooroutofroadtrains.Aroadpassesalongthelogstore.Thesawmillsareinstalledsothatthereceptionsitesareunderthecranespan.AschematicviewofthecraneisshowninFig.1.13506307/99/一seefrontmatter1999ElsevierScienceLtd.Allrightsreserved.PIIS1350一63079800041一7Aseriesofassumptionsmaybemadeafterexaminingtheworkofcranesifthemonthlyremovaloflogsfromtheforestexceedstheprocessingrate,i.e.thereisacreationofalogstore,thecraneexpectswork,beingabovethecentreofaformedpilewiththegrabloweredonthepilestackwhenprocessingexceedsthelogremovalfromtheforest,thecraneexpectsworkaboveanoperationalpileclosetothesawmillwiththegrabloweredonthepilethestoreoflogsvariestheheightofthepilesisconsideredtobeamaximumthestorevariationtakesplacefromthesideoppositetothesawmillthetotalvolumeofaprocessedloadisontheaveragek1.4timesmorethanthetotalvolumeofremovalbecauseofadditionaltransfers.2.1.RemovalintensityItisknownthattheremovalintensityforoneyearisirregularandcannotbeconsideredasastationaryprocess.Thestudyofthecharacterofnonstationaryflowofroadtrainsat23enterprisesSverdlespromforfiveyearshasshownthatthemonthlyremovalintensityevenforoneenterpriseessentiallyvariesfromyeartoyear.Thisisexplainedbythecomplexofvarioussystematicandrandomeffectswhichexertaninfluenceonremovalweatherconditions,conditionsofroadsandlorryfleet,etc.Allwoodbroughttothelogstoreshould,however,beprocessedwithinoneyear.Therefore,thelesspossibilityofremovingwoodintheseasonbetweenspringandautumn,themoreintensivelythewoodremovalshouldbeperformedinwinter.Whileinwintertheremovalintensityexceedstheprocessingconsiderably,insummer,inmostcases,themorefulllengthlogsareprocessedthanaretakenout.Fromtheanalysisof118realizationsofremovalvaluesobservedforoneyear,itispossibletoevaluatetherelativeremovalintensitygtaspercentagesoftheannualloadturnover.TheremovaldatafistedinTable1isconsideredasexpectedvaluesforanycrane,whichcanbeappliedtotheestimationoffatiguelife,and,particularly,foraninspectedcranewithwhichstrainmeasurementwascarriedoutseelater.Itwouldbepossibleforeachcranetotakeadvantageofitsloadturnoverperonemonth,buttoestablishthesedatawithoutspecialstatisticalinvestigationisdifficult.Besides,tosolvetheproblemoflifepredictionaknowledgeoffutureloadsisrequired,whichwetakeasexpectedvaluesoncraneswithsimilaroperationconditions.ThedistributionofremovalvalueQtpermonthperformedbytherelativeintensityqtiswrittenaswhereQistheannualloadturnoverofalogstore,AisthemaximaldesignedstoreoflogsinpercentofQ.SubstitutingthevalueQ,whichfortheinspectedcraneequals400,000m3peryear,andA10,thevolumesofloadstransferredbythecraneareobtained,whicharelistedinTable2,withthetotalvolumebeing560,000m3foroneyearusingK,.2.2.NumberofloadingblocksThesetofoperationssuchasclamping,hoisting,transferring,lowering,andgettingridofaloadcanbeconsideredasoneoperationcycleloadingblockofthecrane.Asaresulttoinvestigations,theoperationtimeofacyclecanbemodeledbythenormalvariablewithmeanequalto11.5minandstandarddeviationto1.5min.unfortunately,thischaracteristiccannotbesimplyusedforthedefinitionofthenumberofoperationcyclesforanyworkperiodasthelocalprocessingisextremelyirregular.Usingatotaloperationtimeofthecraneandevaluationsofcycledurations,itiseasytomakelargeerrorsandincreasethenumberofcyclescomparedwiththerealone.Therefore,itispreferredtoactasfollows.

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