damage tolerance 损伤容限 飞机

://jsm.sagepub.com/cgi/content/abstract/9/6/571Theonlineversionofthisarticlecanbefoundat:Publishedby:://jsm.sagepub.com/cgi/alertsEmailAlerts::::://jsm.sagepub.comDownloadedfromApproachestoDamageAssessmentandDamageToleranceforFRPSandwichStructuresBRIANHAYMAN1,2,*1SectionforStructuralIntegrityandLaboratoriesDetNorskeVeritasAS,N-1322Høvik,Norway2DepartmentofMathematics,UniversityofOslo,NorwayABSTRACT:Areviewismadeofproductiondefectsandin-servicedamagetypesthatariseinsandwichstructureshavingfiberreinforcedplastic(FRP)facesheets.Abriefoverviewisgivenofrelevantdefectanddamagemodelsandhowthesemodelscanbeusedinanassessmentofcriticalitywithregardtolocalandglobalstructure,asabasisfordecidingoncorrectivemeasures,forthecaseofanavalship.Challengesresultingfromlimitationsininspectiontechniquesarediscussed.Theconceptofdamagetoleranceisdiscussedinthelightoftheabove.Itisarguedthatthemostsuitableandeconomicalapproachtoachievingdamagetoleranceisdependentontheapplication.KEYWORDS:FRPsandwichstructures,defects,damage,damageassessment,damagetolerance.INTRODUCTIONCOMPOSITESTRUCTURESCONSISTINGoffiberreinforcedplastics(FRP)containimperfectionsresultingfromeithertheproductionprocessesorsubsequenthandlinganduse.ThisappliesalsotosandwichstructuresinwhichthefacesheetsaremadeofFRP.ManyFRPstructures,suchasthoseusedinmarineapplications,havetraditionallybeendesignedwithoutexplicitlyaddressingsuchdefectsanddamage;productiondefectshavebeenallowedforimplicitlybyapplyingsufficientlyhighfactorsofsafety,andacertainrobustnessinrelationtoaccidentaleventshasbeenbuilt-inbysuchJournalofSANDWICHSTRUCTURESANDMATERIALS,Vol.9—November20075711099-6362/07/060571–26$10.00/0DOI:10.1177/1099636207070853
SAGEPublications2007LosAngeles,London,NewDelhiandSingapore*E-mail:[e-mail]VLIBonMarch4,2009:InspectionandRepairofSandwichStructuresinNavalShips(SaNDI)[1].InthisprojectattentionhasbeenfocusedonthetypesofdefectsanddamagethatneedtobetakenintoaccountwhennavalshipsbuiltinFRPsandwicharedesigned,built,maintainedandoperated,onthemethodsavailabletodetectsuchdefectsanddamage,onthewaysinwhichtheirinfluenceonstructuralperformancemaybeassessed,andonthemethodsavailablefortheirrepair.Theprojecthasdevelopedanintegratedmethodology[2,3]fortheinspection,assessment,andrepairofdefectsanddamage,withattentiontotheimportantquestionsofwhether,when,where,andhowdefectsanddamageshouldberepairedand,inthecaseofin-servicedamage,whethermeasuresshouldbetakentoimposeoperationalrestrictionsintheinterimperiodwhilearepairispending.Anoverviewofsomeofthemainresultsispresentedhere,withdiscussionoftheimplicationsforintroducingmoredamagetolerantdesigninFRPstructuresinshipsandotherapplications.DEFECTSANDDAMAGEINFRPSANDWICHSTRUCTURESTheterms‘defect’and‘damage’arenotuniquelydefined,andaresometimesusedsynonymously.Theauthorpreferstheterms‘productiondefect’and‘in-servicedamage’tomakethemajordistinctionthatisrelevantinpractice.InallFRPcompositestructuresitisimportanttobeabletodetectandrectifybothproductiondefectsandin-servicedamage.ProductionDefectsForsingle-skin(solid)laminatesandfacelaminatesofsandwichstructures,productiondefectsinclude:.dryzones.voids572B.HAYMANatNORTHWESTERNPOLYUNIVLIBonMarch4,2009(givingreducedphysicalproperties).Forsandwichstructures,thefollowingtypesofproductiondefectsmustalsobeconsidered:.face–coredebonds.voidsandinclusionsinthecore.lackofbond(edge-to-edgeandface-to-face)betweencoresheets.In-serviceDamageInaircraftstructuresthemaintypeofin-servicedamageisimpactdamage,typicallyfrombirdstrikes,hail,andobjectsthrownupfromtherunwayduringlandingandtakeoff.Shipstructures,however,mayencounterawiderrangeofc