ASTM-D6272-02塑料弯曲

Designation:D6272–02StandardTestMethodforFlexuralPropertiesofUnreinforcedandReinforcedPlasticsandElectricalInsulatingMaterialsbyFour-PointBending1ThisstandardisissuedunderthefixeddesignationD6272;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversthedeterminationofflexuralpropertiesofunreinforcedandreinforcedplastics,includinghigh-moduluscompositesandelectricalinsulatingmaterialsintheformofrectangularbarsmoldeddirectlyorcutfromsheets,plates,ormoldedshapes.Thesetestmethodsaregenerallyapplicabletorigidandsemirigidmaterials.However,flexuralstrengthcannotbedeterminedforthosematerialsthatdonotbreakorthatdonotfailintheouterfibers.Thistestmethodutilizesafourpointloadingsystemappliedtoasimplysupportedbeam.1.2Thistestmethodmaybeusedwithtwoprocedures:1.2.1ProcedureA,designedprincipallyformaterialsthatbreakatcomparativelysmalldeflections.1.2.2ProcedureB,designedparticularlyforthosematerialsthatundergolargedeflectionsduringtesting.1.2.3ProcedureAshallbeusedformeasurementofflexuralproperties,particularlyflexuralmodulus,unlessthematerialspecificationstatesotherwise.ProcedureBmaybeusedformeasurementofflexuralstrength.1.3Comparativetestsmayberunaccordingtoeitherprocedure,providedthattheprocedureisfoundsatisfactoryforthematerialbeingtested.1.4ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesprovidedinparenthesesareforinforma-tiononly.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.NOTE1—Thistestmethodisequivalentto,butnotidenticaltoISO14125(MethodB).2.ReferencedDocuments2.1ASTMStandards:D618PracticeforConditioningPlasticsforTesting2D638TestMethodforTensilePropertiesofPlastics2D790TestMethodforFlexuralPropertiesofUnreinforcedandReinforcedPlasticsandElectricalInsulatingMateri-als2D883TerminologyRelatingtoPlastics2D4000ClassificationSystemforSpecifyingPlasticMate-rials3D4066ClassificationSystemforNylonInjectionandEx-trusionMaterials(PA)3D5947TestMethodsforPhysicalDimensionsofSolidPlasticSpecimens2E4PracticesforForceVerificationofTestingMachines4E83PracticeforVerificationandClassificationofExten-someters4E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod52.2ISOStandard:6ISO14125(MethodB)3.Terminology3.1Definitions:3.1.1DefinitionsoftermsapplyingtothesetestmethodsappearinTerminologyD883andAnnexA2ofTestMethodD638.4.SummaryofTestMethod4.1Abarofrectangularcrosssectionrestsontwosupportsandisloadedattwopoints(bymeansoftwoloadingnoses),eachanequaldistancefromtheadjacentsupportpoint.Thedistancebetweentheloadingnoses(theloadspan)iseitheronethirdoronehalfofthesupportspan(seeFig.1).Asupportspan-to-depthratioof16:1shallbeusedunlessthereisreasontosuspectthatalargerspan-to-depthratiomayberequired,asmaybethecaseforcertainlaminatedmaterials(seeSection7andNote8forguidance).4.2Thespecimenisdeflecteduntilruptureoccursintheouterfibersoruntilthemaximumfiberstrain(see12.7)of5%isreached,whicheveroccursfirst.1ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlasticsandisthedirectresponsibilityofSubcommitteeD20.10onMechanicalProperties.CurrenteditionapprovedApril10,2002.PublishedJune2002.OriginallypublishedasD6272–98.LastpreviouseditionD6272–00.2AnnualBookofASTMStandards,Vol08.01.3AnnualBookofASTMStandards,Vol08.02.4AnnualBookofASTMStandards,Vol03.01.5AnnualBookofASTMStandards,Vol14.02.6AvailablefromAmericanNationalStandardsInstitute,25W.43rdSt.,4thFloor,NewYork,NY10036.1*ASummaryofChangessectionappearsattheendofthisstandard.Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.5.SignificanceandUse5.1Flexuralpropertiesdeterminedbythistestmethodareespeciallyusefulforqualitycontrolandspecificationpurposes.5.2ThistestmethodmaybemoresuitedforthosematerialsthatdonotfailwithinthestrainlimitsimposedbyTestMethodD790.Themajordifferencebetweenfourpointandthreepointbendingmodesisthelocationofthemaximumbendingmomentandmaximumaxialfiberstress.Infourpointbendingthemaximumaxialfiberstressisuniformlydistributedbe-tweentheloadingnoses.Inthreepointbendingthemaximumaxialfiberstressislocatedimmediatelyundertheloadingnose.5.3Flexuralpropertiesmayvarywithspecimendepth,temperature,atmosphericconditions,andthedifferenceinrateofstrainingspecifiedinProceduresAandB.5.4Beforeproceedingwiththistestmethod,referenceshouldbemadetothespecificationofthematerialbeingtested.Anytestspecimenpreparation,conditioning,dimensions,ortestingparameterscoveredinthematerialspecification,orboth,shalltakeprecedenceoverthosementionedinthistestmethod.Iftherearenomaterialspecifications,thenthesedefaultconditionsapply.Table1inClassificationD4000liststheASTMmaterialsstandardsthatcurrentlyexist.6.Apparatus6.1TestingMa