Designation:D4896−01(Reapproved2016)StandardGuideforUseofAdhesive-BondedSingleLap-JointSpecimenTestResults1ThisstandardisissuedunderthefixeddesignationD4896;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONThetruestrengthofanadhesiveisamaterialpropertyindependentofthejointgeometry,adherendproperties,andload,andisagoodstartingpointfordetermininganallowabledesignstress.Allowablestressesinshearandtensionareneededtodesignsafe,efficient,adhesivelybondedjointsandstructures.Thetrueshearstrength,however,cannotbeeasilydeterminedusingsingle-lapspecimens.Manyfactorsaffecttheapparentshearstrengthofanadhesivewhenmeasuredwithasmalllaboratoryspecimen,andinparticular,withasingle-lapspecimen.Forexample,thefailureofatypicalsingle-lapspecimen,isusuallycontrolledbythetensilestressintheadhesive,andnotbytheshearstress.Thefactorsthatcontrolthetensilestressinlap-jointspecimen,andthus,theapparentshearstrengtharethesizeandshapeofthespecimen,thepropertiesoftheadherends,thepresenceofinternalstressesorflaws,andthechangesthattakeplaceinthespecimenduetoadhesivecureandtheenvironment.Similarlythesefactorsaffecttheapparenttensilestrengthofanadhesiveinbutt-jointtestspecimens.Duetotheeffectsofthesefactors,theapparentshearstrengthobtainedthroughmeasurementsonsmalllaboratoryspecimensmayvarywidelyfromthetrueshear-ortensile-strengthvaluesneededtodetermineallowableshearandtensiondesignstresses.Theobjectivesofthisguideare:todevelopanappreciationofthefactorsthatinfluencestrengthandotherstressmeasurementsthataremadewithsmalllaboratorytestspecimens;tofostertheacceptableusesofthewidelyusedthin-adherendsingle-lap-jointtest;and,specifically,topreventmisuseofthetestresults.1.Scope1.1Thisguideisdirectedtowardthesafeandappropriateuseofstrengthvaluesobtainedfromtestmethodsusingsingle-lapadhesivejo...
