Designation:D4255/D4255M−15aStandardTestMethodforIn-PlaneShearPropertiesofPolymerMatrixCompositeMaterialsbytheRailShearMethod1ThisstandardisissuedunderthefixeddesignationD4255/D4255M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thistestmethoddeterminesthein-planeshearproper-tiesofhigh-modulusfiber-reinforcedcompositematerialsbyeitheroftwoprocedures.InProcedureA,laminatesclampedbetweentwopairsofloadingrailsaretested.Whenloadedintensiontherailsintroduceshearforcesinthespecimen.InProcedureB,laminatesclampedonoppositeedgeswithatensileorcompressiveforceappliedtoathirdpairofrailsinthecenteraretested.1.2Applicationofthistestmethodislimitedtocontinuous-fiberordiscontinuous-fiber-reinforcedpolymermatrixcom-positesinthefollowingmaterialforms:1.2.1Laminatescomposedonlyofunidirectionalfibrouslaminae,withthefiberdirectionorientedeitherparallelorperpendiculartothefixturerails.1.2.2Laminatescomposedonlyofwovenfabricfilamentarylaminaewiththewarpdirectionorientedeitherparallelorperpendiculartothefixturerails.1.2.3Laminatesofbalancedandsymmetricconstruction,withthe0°directionorientedeitherparallelorperpendiculartothefixturerails.1.2.4Short-fiber-reinforcedcompositeswithamajorityofthefibersbeingrandomlydistributed.NOTE1—Additionaltestmethodsfordeterminingin-planeshearpropertiesofpolymermatrixcompositesmaybefoundinTestMethodsD3518/D3518M,D5379/D5379M,D5448/D5448M,andD7078/D7078M.1.3Thereproducibilityofthistestmethodcanbeaffectedbythepresenceofshearstressgradientsinthegagesectionandstressconcentrationsatthegrippingareas.TestMethodsD5379/D5379MandD7078/D7078Mprovidesuperiorshearresponseincomparisontothistestmethod,astheirspecimenconfigurationsproducearelativelypureanduniformshearstressstateint...
