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外文翻译--弯曲的金属疲劳试验的钢丝绳飞机救援起重机 英文版.pdf

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外文翻译--弯曲的金属疲劳试验的钢丝绳飞机救援起重机 英文版.pdf

BENDINGFATIGUETESTSONAMETALLICWIREROPEFORAIRCRAFTRESCUEHOISTSMARCOGIGLIO,ANDREAMANESDEPARTMENTOFMECHANICS,POLITECNICODIMILANO,VIALAMASA34,20158MILAN,ITALYRECEIVED29JULY2002;ACCEPTED24AUGUST2002ABSTRACTDURINGNORMALOPERATION,THEENDSOFHELICOPTERRESCUEHOISTROPES,TOWHICHAHOOKISATTACHED,CANBESUBJECTTOBENDINGSTRESSCAUSEDBYVIBRATIONSTHISHAPPENSINTHEEVENTOFPARTIALORTOTALRECOVERYOFTHEHOOKINTOITSLODGINGWITHOUTASPRINGLOADEDBLOCKINGSYSTEMTHESWINGINGOFTHEROPEENDCONSEQUENTLYCAUSESBENDINGOFTHEROPENEARTHETERMINAL,WITHRESULTANTFATIGUESTRESSTHATCANLEADQUICKLYTOBREAKAGEORDAMAGEOFTHEROPEASERIESOFALTERNATINGBENDINGFATIGUETESTSUSINGACONSTANTLOAD,SIMILARTOTHOSEKNOWNASBOSBENDINGOVERSHEAVETESTS,WERECARRIEDOUTTHESESIMULATETHEEffECTIVEWORKINGCONDITIONSOFARESCUEHOISTTHISPAPERDESCRIBESMODIfiCATIONSTOTESTMACHINERY,THETESTMETHODANDTHEDATAOBTAINED;STATISTICALANALYSISOFTHISDATAENABLEDUSTOMAKEAROPELIFEPREDICTIONWHICHWASTHENEXPERIMENTALLYCONfiRMEDBYRUNOUTSONTESTROPES2002ELSEVIERSCIENCELTDALLRIGHTSRESERVEDKEYWORDSWIREROPES;SHEAVEFATIGUE;HOISTS;AIRCRAFT1INTRODUCTIONWIREROPES,LIKEROPESINGENERALANDALSOCHAINS,ARECOMMONLYUSEDFORTRACTIONLOADTRANSMISSIONDESPITEITSWIDESPREADUSE,WIREROPEREMAINSANEXTREMELYCOMPLEXANDLITTLEKNOWNPIECEOFEQUIPMENTITSCONSTRUCTION,THECONSIDERABLEANDDIVERSEINTERNALCONTACTFORCES,THEWEARDUETOTHESEFORCESANDTOCONTACTWITHDRUMS,PULLEYSORSHEAVES,ALLMAKEACOMPLETELYANALYTICALAPPROACHTORELIABILITYEXTREMELYDIffiCULTEVENTODAY,EXPERIMENTALTESTINGPLAYSANIMPORTANTROLEINTHEANALYSISOFROPESUBJECTEDTOAPARTICULARLOAD,ESPECIALLYASREGARDSFATIGUEANALYSISWHERETHEBREAKINGOFSTRANDSRESULTSFROMVARYINGTYPESOFTESTANDLOADTHEPURPOSEOFTHISPAPERISTOINVESTIGATETHEBEHAVIOUROFROPEUSEDONAHELICOPTERRESCUEHOISTWEANALYSETHECIRCUMSTANCEINWHICHTHEHOOKATTACHEDTOTHEENDOFTHEROPEHASBEENTOTALLYORPARTIALLYRECOVEREDINTOITSLODGINGANDISLEFTFREETOSWINGINCORRECTHOOKLODGINGORINSUffiCIENTPRELOADINGOFTHESPRINGBLOCKINGSYSTEMRESULTINBENDINGOFTHEENDSECTIONOFTHEROPE,WHICHMAYTHENHIT13506307/03/SEEFRONTMATTER2002ELSEVIERSCIENCELTDALLRIGHTSRESERVEDPIIS1350630702000432ENGINEERINGFAILUREANALYSIS102003223–235WWWELSEVIERCOM/LOCATE/ENGFAILANALCORRESPONDINGAUTHORTEL390239947354;FAX39070638377EMAILADDRESSMARCOGIGLIOPOLIMIITMGIGLIOTHEGUIDEWHEELSOFTHEWINCHSEEFIG1BREAKAGEANDDAMAGETOROPEWITHOUTTHEAPPLICATIONOFANYTRACTIONLOAD,ANDTHEREFORENOTOTHERWISEEXPLAINABLE,HAVEBEENATTRIBUTEDTOTHISPARTICULAROPERATINGCONDITIONTHISWIREROPE,LIKEALLAERONAUTICALCOMPONENTS,MUSTBEOPTIMISEDFORWEIGHT;THEROPEHASASAFETYFACTOROF5ONTHESTATICFAILURELOADLESSTHANROPESFORCIVILANDINDUSTRIALUSEBUTMUSTBEREPLACEDAFTER1500COMPLETELOWERRAISECYCLESUNDEROPERATINGLOADSITIS,THEREFORE,REASONABLETOASSUMETHATWEARANDDAMAGEDUETOVIBRATIONALSWINGING,EVENWHENTHEHOISTISNOTINUSE,CANLEADTOPROGRESSIVEANDMARKEDWEAKENINGOFTHERESISTANTSECTIONASSUMINGACONSTANTPRELOADEQUALTOTHEWEIGHTOFTHEHOOKMULTIPLIEDBYANAPPROPRIATEFACTOR,WHICHTAKESINTOACCOUNTINERTIAFORCES,WESTUDIEDTHEBENDINGFATIGUEBEHAVIOUROFWIREROPEDURINGCYCLICALLYREPEATEDSWINGINGONTHEGUIDEWHEELS,ATAfiXEDALTERNATINGANGLE,INORDERTOESTABLISHWHETHERTHEREEXISTSANANGULARVARIATIONBELOWWHICHNODAMAGETOTHEROPEOCCURSTHEINSTRUMENTATIONUSEDWASDESIGNEDANDCONSTRUCTEDSPECIfiCALLYFORTHESETESTSITREPRODUCESTHESWINGINGOFTHEROPEENDANDTHECONSEQUENTALTERNATINGBENDINGFATIGUESTRESSOFTHEROPEATTHESHEAVE2BACKGROUNDWEFOUNDNOPREVIOUSPUBLISHEDSTUDIESCONCERNINGBENDINGTESTSCARRIEDOUTWITHTHEMETHODSUSEDINTHISEXPERIMENTINPUBLISHEDRESEARCHONBENDING,ROPEHASBEENWOUNDOffANDONTOAPULLEYOFAGIVENDIAMETERANDTHUSASSUMESTHEBENDINGRADIUSFORADEfiNEDLENGTHINTHEEXPERIMENTALTESTSPERFORMED,THEBENDINGRADIUSOFTHEROPEONTHESHEAVEDIffERSFROMPOINTTOPOINTMOREOVER,THEALTERNATINGBENDINGOFTHEROPEENDINDUCESAVARIABLESIGNBENDINGLOADINGINEVERYSECTIONOFTHEROPEINEVERYCYCLE,THUSDETERMININGALTERNATINGFATIGUESTRESSOFTHEWIRESINCONTACTWITHTHESHEAVESFATIGUETESTSONPULLEYSAREFORESEENUNDERTHEMILW84140STANDARD1FORHELICOPTERRESCUEHOISTROPESTHEROPEINOURCASE,AROPEWITHANOMINALDIAMETEROF3/16INCHES,SUITABLYCONDITIONED,MUSTFIG1TERMINALBENDING224MGIGLIO,AMANES/ENGINEERINGFAILUREANALYSIS102003223–235PERFORM150,000CYCLESONAPULLEYWITHATHROATDIAMETEROF1781INCHES4523MM,WITHAPRELOADOF225POUNDS10008N,ANDMUSTSUBSEQUENTLYHAVERESIDUALMECHANICALCHARACTERISTICSTOALLOWATENSILESTRENGTHOFOVER2000POUNDS889644NASIMILARTESTINTERMSOFTESTSYSTEM,AIMEDATOBTAININGMOREDETAILEDINFORMATIONONDEFORMATIONSINTHEWIRESMAKINGUPTHEROPE,ISTHATCARRIEDOUTBYRIDGEETAL2,3INTHISARTICLE,MEASUREMENTSARETAKENUSINGSTRAINGAUGESPLACEDONTHEWIRESTHICKERTHAN1MMOFACOMPLEXSECTIONROPEDURINGWINDINGOVERATESTPULLEYTHEDIAMETEROFTHEPULLEYIS18TIMESTHATOFTHEROPEANDTHEPRELOADIS20OFTHETENSILESTRENGTHOFTHEROPEITCANBESEENHOW,INITIALLY,WHENTHEROPEISONLYAXIALLYLOADED,WIRESTHATSHOULDGIVESIMILARMEASUREMENTSACTUALLYDISPLAYDIffERENTSTRAINSPROBABLYDUETOIMPERFECTIONSINTHEROPECONSTRUCTION,ANDHOWTHESEDIffERENCESTENDTODISAPPEARQUICKLYDURINGTHEBENDINGFATIGUETESTSTHEAMPLITUDEANDTHESHAPEOFTHESTRAINCYCLESRECORDEDDONOTCHANGESIGNIfiCANTLYDURINGTHEFATIGUETESTTHEAUTHORSSHOWEXPERIMENTALLYHOWDEGRADATIONANDIMPAIREDQUALITYDUETOWRONGUSE,WEARANDTHEMANUFACTURINGPROCESS,CONSIDERINGTHECONfiGURATIONANDLOADUSEDBYRIDGEETAL,HAVEONLYALIMITEDINflUENCEONBENDINGFATIGUELIFE,WHICHDEPENDSMAINLYONTHEROPE’SNOMINALCONSTRUCTIONANDONTHEROPE/SHEAVEDIAMETERRATIONABIJOUANDHOBBS4ANALYSE,INAWIDEVARIETYOFCASES,THEFATIGUEBEHAVIOUROFAROPEWOUNDONSMALLDRUM,SUBJECTEDTOAPRELOADPROPORTIONALTOITSTENSILESTRENGTH40–60THEIRSTUDYLOOKSINTOTHEINflUENCEOFPARAMETERSINCLUDINGTHEGEOMETRYOFTHEGROOVEINWHICHTHEROPERESTS,THETYPEOFWORKINGOFTHEPULLEYTHROATANDTHETREATMENTCARRIEDOUTONTHEWIRESOFTHEROPE,ASWELLASTHEEffECTOFTHEDIAMETEROFTHEROPEANDOFANYLUBRICATINGORCONTAMINATINGAGENTSSUCHASWATERORSANDITISINTERESTINGTONOTEHOWTWOIDENTICALSHEAVESMADEBYTWODIffERENTMANUFACTURERSPRODUCEDIffERENTROPEFATIGUEENDURANCETHISCONfiRMSTHATFATIGUELIFECANALSOTHEREFOREDEPENDONTHEMICROSCOPICCHARACTERISTICSOFTHESURFACESWITHWHICHTHEROPECOMESINTOCONTACTFROMNABIJOUANDHOBBS’WORK,ITCANBESEENTHATFORLOWLOADANDHIGHSHEAVECURVATURECOMPAREDTOTHEROPEDIAMETER,THEPREDOMINANTFORMOFBREAKAGEISTHATDUETOWEARCAUSEDBYCONTACTWITHTHEPULLEYINTHECASEOFHIGHLOADANDSMALLDIAMETERSHEAVE,ONTHEOTHERHAND,THEfiRSTTYPEOFWEARTOAPPEARISTHATDUETOSLIDINGBETWEENWIRESTHEINTERNALSLIDINGBETWEENWIRES,INSUCHACONfiGURATION,HASALSOBEENOBSERVEDANALYTICALLYBYNABIJOUANDHOBBS5THETWOGROUPSOFARTICLESOUTLINEDABOVEARENOTCONflICTINGBUTHELPPROVIDEAMORETHOROUGHUNDERSTANDINGOFTHECOMPLEXPHENOMENONOFBOSTHEFATIGUELIFEANDTHECONSEQUENTFAILUREOFABOSTESTEDROPEDEPEND,UNEQUIVOCALLY,ONFRETTINGWIRE–WIRE,WIRE–SHEAVEFATIGUELIFESEEMS,HOWEVER,TOBEINflUENCEDMAINLYBYTHENOMINALLOADCONDITIONSANDDIAMETERRATIOS,ANDONLYSLIGHTLYBYPARTICULARUNFAVOURABLEINITIALCONDITIONSORPROGRESSIVEINITIALYIELDINGTHESECONDITIONSUNDERLINEASUBSTANTIALDIffERENCEOFTHEBOSFROMTHEAXIALFATIGUELOADWHERENOTCHESANDWEARRESULTINACONSIDERABLEREDUCTIONINTHEFATIGUELIFETHEIMPORTANCEOFWEARDUETOFRETTINGWASfiRSTHIGHLIGHTEDBYSTARKEYANDCRESS6THEIRSTUDYWAS,INFACT,THEfiRSTTOIDENTIFYTHEEXISTENCEOFTWODIffERENT‘CRITICALREGIONS’INAROPETHEfiRSTONERELATIVETOTHELINEARCONTACTBETWEENADJACENTSTRANDSINTHESAMELAYER,THESECONDRELATIVETOLOCALAND,THEREFORE,MOREDANGEROUSCONTACTBETWEENTWOWIRESBELONGINGTOTWOADJACENTLAYERSINSTATICTESTS,THEEffECTOFWEARHASACONSIDERABLEINflUENCEONTENSILESTRENGTHDESILVAANDFONG7ANALYSETHESIGNIfiCANTRESIDUALLOADREDUCTIONINROPESSUBJECTTOWEARBOTHINTHELABORATORYANDDURINGACTUALOPERATION,ANDCOMPARETHEIRRESULTSWITHCURRENTSTANDARDSONTHEREPLACEMENTOFROPESUBJECTTOWEAR,INPARTICULARISO4309INASIMILARWAY,KURUPPUETAL8ANALYSETHESAMEREDUCTIONINMECHANICALCHARACTERISTICSANDREACHSIMILARBUTLESSDRASTICCONCLUSIONSTOTHOSEOFTHESTUDYBYDESILVAANDFONGINBOTHSTUDIES,HOWEVER,ITCANBESEENHOWAMETALLICAREALOSSOFAFEWPERCENTAGEPOINTSRESULTSINTENSILESTRENGTHREDUCTIONSOFABOUT10ASPREVIOUSLYSTATED,PUBLISHEDRESEARCHCONTAINSNOSTUDIESONFATIGUEBEHAVIOURWHENTHEWINDINGANGLEOFTHEROPEONTHESHEAVEISLIMITEDANDWHENTHEREISAVERYLOWCONSTANTPRELOAD,INOTHERWORDS,UNDERTHECONDITIONSAPPLIEDINTHISTESTPROJECTMGIGLIO,AMANES/ENGINEERINGFAILUREANALYSIS102003223–2352253THEROPETESTEDTHEROPETESTEDCORRESPONDSTOMILW83140SPECIfiCATIONSASTYPEI,19C27STAINLESSSTEEL,PREFORMED,NONROTATINGFORHELICOPTERRESCUEHOISTSCABLESOFTHISCONSTRUCTIONCONSISTOFONECOREOFSEVENSTRANDSOFSEVENWIRESEACHFORATOTALOF49WIRESANDANOUTERLAYEROF12STRANDSOFSEVENWIRESEACHFORATOTALOF84WIRESTHEINNERCOREISLANGLAY,LEFTLAY;THEOUTERLAYERISREGULARLAY,RIGHTLAYTHETOTALNUMBEROFWIRESINTHECABLESIS133THEROPEDIAMETERIS3/16INCH476MM4THETESTMACHINE41DESCRIPTIONOFTHEMACHINEBEFOREMODIfiCATIONTHEMACHINEUSEDFORTHETESTS,THEMETROCOMT6ALTESTFREQUENCY05HZ,MAXIMUMANGULARVARIATION180C14,WASMADETOPERFORMALTERNATINGTORSIONFATIGUETESTSTHETESTROPESAREPLACEDBETWEENTWOCLAMPS,ONEOFWHICHTURNSAROUNDITSAXIS;THEOTHERISfiXEDSEEFIG2THEMACHINEWASMODIfiEDTOBEABLETOCARRYOUTTHEALTERNATINGBENDINGTESTSTHEMACHINE’SMOBILECLAMPINGHEADWASREPLACEDBYAROPETERMINALSUPPORTSPECIALLYDESIGNEDFORTHETESTS,ANDASERVICESTRUCTURE,NECESSARYTOCREATETHEDESIREDTESTCONDITIONS,WASADDED42ROPETERMINALSUPPORTTHESUPPORTALLOWSBOTHANOPTIMALLOCKINGOFTHEROPETERMINALANDTHECREATIONOFACTUALLOADCONDITIONSTHESUPPORTFIG3WASDESIGNEDWITHTHEAIMOFMAINTAININGTHEMACHINE’SABILITYTOPERFORMROTATIONSWITHAMAXIMUMANGULARVARIATIONOFC6180C14TWOSHEAVESAREMOUNTEDONTHESUPPORT,SYMMETRICALLYPLACEDNEARTHEMACHINEDRIVESHAFTAXISTHEYAREANEXACTREPRODUCTIONOFTHESHEAVESOFAHELICOPTERRESCUEHOISTAND,THANKSTOANASSEMBLYWITHTWODEGREESOFFREEDOM,THEIRPOSITIONISTHESAMEASTHATWHICHTHEYHAVEWHENINOPERATION;DURINGBENDING,THEROPELIESOVERTHESESHEAVESSEEFIG4THESUPPORTISfiXEDTOTHETESTMACHINEBYMEANSOFAHUBSHAFTCOUPLINGWITHTANGENTIALKEYANDBLOCKINGSCREWTHETWOSHEAVESBETWEENWHICHTHEROPERUNSAREMOUNTEDONSHAFTSWITHTEflONBEARINGSINORDERTOLIMITTHEEffECTSOFWEAR;THESHEAVESHAVEBEENHARDENEDANDPOLISHEDTOAVOIDTHEPOSSIBILITYOFSURFACEDAMAGESEEFIG5ASURFACEHARDNESSTESTGAVEANHRCOF63THESUPPORTWASDESIGNEDANDBUILTWITHTOLERANCESTOGUARANTEEC15PARALLELISMBETWEENDRIVESHAFTANDSHEAVEAXIS;C15PERPENDICULARITYBETWEENTHEAXISOFTHECABLEANDTHATOFTHESHEAVES;C15flATNESSOFTHESUPPORTfiXINGHOLEAXISFIG2METROCOMT6ALBEFOREMODIfiCATION226MGIGLIO,AMANES/ENGINEERINGFAILUREANALYSIS102003223–235

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