Analytical Methodology for Predicting the Onset of

December1998NASA/TM-1998-208975MethodologyforPredictingtheOnsetofWidespreadFatigueDamageinLap-SpliceJointsJ.C.Newman,Jr.,C.E.Harris,R.S.Piascik,andD.S.DawickeLangleyResearchCenter,Hampton,VirginiaTheNASASTIProgramOffice...inProfileSinceitsfounding,NASAhasbeendedicatedtotheadvancementofaeronauticsandspacescience.TheNASAScientificandTechnicalInformation(STI)ProgramOfficeplaysakeypartinhelpingNASAmaintainthisimportantrole.TheNASASTIProgramOfficeisoperatedbyLangleyResearchCenter,theleadcenterforNASA’sscientificandtechnicalinformation.TheNASASTIProgramOfficeprovidesaccesstotheNASASTIDatabase,thelargestcollectionofaeronauticalandspacescienceSTIintheworld.TheProgramOfficeisalsoNASA’sinstitutionalmechanismfordisseminatingtheresultsofitsresearchanddevelopmentactivities.TheseresultsarepublishedbyNASAintheNASASTIReportSeries,whichincludesthefollowingreporttypes:•TECHNICALPUBLICATION.ReportsofcompletedresearchoramajorsignificantphaseofresearchthatpresenttheresultsofNASAprogramsandincludeextensivedataortheoreticalanalysis.Includescompilationsofsignificantscientificandtechnicaldataandinformationdeemedtobeofcontinuingreferencevalue.NASAcounterpartofpeer-reviewedformalprofessionalpapers,buthavinglessstringentlimitationsonmanuscriptlengthandextentofgraphicpresentations.•TECHNICALMEMORANDUM.Scientificandtechnicalfindingsthatarepreliminaryorofspecializedinterest,e.g.,quickreleasereports,workingpapers,andbibliographiesthatcontainminimalannotation.Doesnotcontainextensiveanalysis.•CONTRACTORREPORT.ScientificandtechnicalfindingsbyNASA-sponsoredcontractorsandgrantees.•CONFERENCEPUBLICATION.Collectedpapersfromscientificandtechnicalconferences,symposia,seminars,orothermeetingssponsoredorco-sponsoredbyNASA.•SPECIALPUBLICATION.Scientific,technical,orhistoricalinformationfromNASAprograms,projects,andmissions,oftenconcernedwithsubjectshavingsubstantialpublicinterest.•TECHNICALTRANSLATION.English-languagetranslationsofforeignscientificandtechnicalmaterialpertinenttoNASA’smission.SpecializedservicesthatcomplementtheSTIProgramOffice’sdiverseofferingsincludecreatingcustomthesauri,buildingcustomizeddatabases,organizingandpublishingresearchresults...evenprovidingvideos.FormoreinformationabouttheNASASTIProgramOffice,seethefollowing:•AccesstheNASASTIProgramHomePageat•[e-mail]•FaxyourquestiontotheNASASTIHelpDeskat(301)621-0134•PhonetheNASASTIHelpDeskat(301)621-0390•Writeto:NASASTIHelpDeskNASACenterforAeroSpaceInformation7121StandardDriveHanover,MD21076-1320NationalAeronauticsandSpaceAdministrationLangleyResearchCenterHampton,Virginia23681-2199December1998NASA/TM-1998-208975MethodologyforPredictingtheOnsetofWidespreadFatigueDamageinLap-SpliceJointsJ.C.Newman,Jr.,C.E.Harris,R.S.Piascik,andD.S.DawickeLangleyResearchCenter,Hampton,VirginiaAvailablefrom:NASACenterforAeroSpaceInformation(CASI)NationalTechnicalInformationService(NTIS)7121StandardDrive5285PortRoyalRoadHanover,MD21076-1320Springfield,VA22161-2171(301)621-0390(703)605-6000METHODOLOGYFORPREDICTINGTHEONSETOFWIDESPREADFATIGUEDAMAGEINLAP-SPLICEJOINTSJ.C.Newman,Jr.,C.E.Harris,R.S.PiascikandD.S.DawickeNASALangleyResearchCenterHampton,VirginiaUSAABSTRACTNASAhasconductedanAirframeStructuralIntegrityProgramtodevelopthemethodologytopredicttheonsetofwidespreadfatiguedamageinlap-splicejointsoffuselagestructures.Severalstressanalysiscodeshavebeendevelopedorenhancedtoanalyzethelap-splice-jointconfiguration.Fatiguelivesinlap-splice-jointspecimensandfatigue-crackgrowthinastructuralfatiguetestarticleagreedwellwithcalculationsfromsmall-cracktheoryandfatigue-crack-growthanalyseswiththeFASTRANcode.Residual-strengthanalysesoflaboratoryspecimensandwidestiffenedpanelswerepredictedquitewellfromthecriticalcrack-tip-openingangle(CTOA)fracturecriterionandelastic-plasticfinite-elementanalyses(two-orthree-dimensionalcodesandtheSTAGSshellcode).INTRODUCTIONInthepastdecade,NASAincollaborationwiththeFederalAviationAdministration(FAA)andaircraftindustryhasconductedaprogramtodevelopthemethodologytopredicttheonsetofwidespreadfatiguedamage(WFD)inlap-splicejointsoffuselagestructures[1].TheonsetofWFDisdefinedasthelifeatwhichfatiguecrackinghasdevelopedtosuchanextentthatresidualstrengthisreducedbelowstructuralrequirements.Eachaircraftmanufacturerhasdevelopedin-housedurabilityanddamage-toleranceanalysismethodsthatarebasedontheirproductdevelopmenthistory.Toenhancethesemethods,NASAhasadoptedtheconceptofananalytical“toolbox”thatincludesanumberofadvancedstructuralanalysiscodeswhichrepresentthecomprehensivefracturemechanicscapabilitytopredict2theonsetofWFD.Thesestructuralanalysistoolshavecapabilitiesrangingfromanonlinearfinite-element-basedstress-analysiscodefortwo-andthree-dimensionalbuilt-upstructureswithcrackstoafatigueandfractureanalysiscodethatusesstress-intensityfactorsandmaterialcrack-growthproperties.Developmentoftheseadvancedstructuralanalysiscodeshasbeenguidedbythephysicalevidenceofthefatigueandfractureprocessinaircraftmaterialsandstructures.Inaddition,critica