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英文原文：FatiguelifepredictionofthemetalworkofatravellinggantrycraneV.A.KopnovAbstractIntrinsicfatiguecurvesareappliedtoafatiguelifepredictionproblemofthemetalworkofatravelinggantrycrane.Acrane,usedintheforestindustry,wasstudiedinworkingconditionsatalogyard,anstrainmeasurementsweremade.Forthecalculationsofthenumberofloadingcycles,therainflowcyclecountingtechniqueisused.Theoperationsofasampleofsuchcraneswereobservedforayearfortheaveragenumberofoperationcyclestobeobtained.Thefatiguefailureanalysishasshownthatfailuressomeelementsaresystematicinnatureandcannotbeexplainedbyrandomcauses.卯1999ElsevierScienceLtd.Allrightsreserved.Keywords:Cranes;Fatigueassessment;Straingauging1.IntroductionFatiguefailuresofelementsofthemetalworkoftravelinggantrycranesLT62Bareobservedfrequentlyinoperation.Failuresasfatiguecracksinitiateandpropagateinweldedjointsofthecranebridgeandsupportsinthree-fouryears.Suchcranesareusedintheforestindustryatlogyardsfortransferringfull-lengthandsawnlogstoroadtrains,havingaload-fittingcapacityof32tons.Morethan1000cranesofthistypeworkattheenterprisesoftheRussianforestindustry.Theproblemwasstatedtofindtheweakestelementslimitingthecranes'fives,predicttheirfatiguebehavior,andgiverecommendationstothemanufacturersforenhancingthefivesofthecranes.2.AnalysisofthecraneoperationFortheanalysis,atravelinggantrycraneLT62BinstalledatlogyardintheYekaterinburgregionwaschosen.Thecraneservestwosawmills,createsalogstore,andtransferslogstooroutofroadtrains.Aroadpassesalongthelogstore.Thesawmillsareinstalledsothatthereceptionsitesareunderthecranespan.AschematicviewofthecraneisshowninFig.1.1350-6307/99/$一seefrontmatter1999ElsevierScienceLtd.Allrightsreserved.PII:S1350一6307(98)00041一7Aseriesofassumptionsmaybemadeafterexaminingtheworkofcranes:·ifthemonthlyremovaloflogsfromtheforestexceedstheprocessingrate,i.e.thereisacreationofalogstore,thecraneexpectswork,beingabovethecentreofaformedpilewiththegrabloweredonthepilestack;·whenprocessingexceedsthelogremovalfromtheforest,thecraneexpectsworkaboveanoperationalpileclosetothesawmillwiththegrabloweredonthepile;·thestoreoflogsvaries;theheightofthepilesisconsideredtobeamaximum;·thestorevariationtakesplacefromthesideoppositetothesawmill;·thetotalvolumeofaprocessedloadisontheaveragek=1.4timesmorethanthetotalvolumeofremovalbecauseofadditionaltransfers.2.1.RemovalintensityItisknownthattheremovalintensityforoneyearisirregularandcannotbeconsideredasastationaryprocess.Thestudyofthecharacterofnon-stationaryflowofroadtrainsat23enterprisesSverdlespromforfiveyearshasshownthatthemonthlyremovalintensityevenforoneenterpriseessentiallyvariesfromyeartoyear.Thisisexplainedbythecomplexofvarioussystematicandrandomeffectswhichexertaninfluenceonremoval:weatherconditions,conditionsofroadsandlorryfleet,etc.Allwoodbroughttothelogstoreshould,however,beprocessedwithinoneyear.Therefore,thelesspossibilityofremovingwoodintheseasonbetweenspringandautumn,themoreintensivelythewoodremovalshouldbeperformedinwinter.Whileinwintertheremovalintensityexceedstheprocessingconsiderably,insummer,inmostcases,themorefull-lengthlogsareprocessedthanaretakenout.Fromtheanalysisof118realizationsofremovalvaluesobservedforoneyear,itispossibletoevaluatetherelativeremovalintensityg(t)aspercentagesoftheannualloadturnover.TheremovaldatafistedinTable1isconsideredasexpectedvaluesforanycrane,whichcanbeappliedtotheestimationoffatiguelife,and,particularly,foraninspectedcranewithwhichstrainmeasurementwascarriedout(seelater).Itwouldbepossibleforeachcranetotakeadvantageofitsloadturnoverperonemonth,buttoestablishthesedatawithoutspecialstatisticalinvestigationisdifficult.Besides,tosolvetheproblemoflifepredictionaknowledgeoffutureloadsisrequired,whichwetakeasexpectedvaluesoncraneswithsimilaroperationconditions.ThedistributionofremovalvalueQ(t)permonthperformedbytherelativeintensityq(t)iswrittenaswhereQistheannualloadturnoverofalogstore,AisthemaximaldesignedstoreoflogsinpercentofQ.SubstitutingthevalueQ,whichfortheinspectedcraneequals400,000m3peryear,andA=10%,thevolumesofloadstransferredbythecraneareobtained,whicharelistedinTable2,withthetotalvolumebeing560,000m3foroneyearusingK,.2.2.NumberofloadingblocksThesetofoperationssuchasclamping,hoisting,transferring,lowering,andgettingridofaloadcanbeconsideredasoneoperationcycle(loadingblock)ofthecrane.Asaresulttoinvestigations,theoperationtimeofacyclecanbemodeledbythenormalvariablewithmeanequalto11.5minandstandarddeviationto1.5min.unfortunately,thischaracteristiccannotbesimplyusedforthedefinitionofthenumberofoperationcyclesforanyworkperiodasthelocalprocessingisextremelyirregular.Usingatotaloperationtimeofthecraneandevaluationsofcycledurations,itiseasytomakelargeerrorsandincreasethenumberofcyclescomparedwiththerealone.Therefore,itispreferredtoactasfollows.Thevolumeofaunitloadcanbemodeledbyarandomvariablewithadistributionfunction(t)havingmean22m3andstandarddeviation6;一3m3,withthenominalvolumeofonepackbeing25m3.Then,knowingthetotalvolumeofaprocessedloadforamonthoryear,itispossibletodeterminedistributionparametersof