ASTM D638_2003

StandardTestMethodfor

TensilePropertiesofPlastics1ThisstandardisissuedunderthefixeddesignationD638;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.

--``,```-`-`,,`,,`,`,,`---1.Scope*

1.1Thistestmethodcoversthedeterminationofthetensilepropertiesofunreinforcedandreinforcedplasticsintheformofstandarddumbbell-shapedtestspecimenswhentestedunderdefinedconditionsofpretreatment,temperature,humidity,andtestingmachinespeed.

1.2Thistestmethodcanbeusedfortestingmaterialsofanythicknessupto14mm[0.55in.].However,fortestingspecimensintheformofthinsheeting,includingfilmlessthan1.0mm[0.04in.]inthickness,TestMethodsD882isthepreferredtestmethod.Materialswithathicknessgreaterthan14mm[0.55in.]mustbereducedbymachining.

1.3ThistestmethodincludestheoptionofdeterminingPoisson’sratioatroomtemperature.

NOTE1—ThistestmethodandISO527-1aretechnicallyequivalent.NOTE2—Thistestmethodisnotintendedtocoverprecisephysicalprocedures.Itisrecognizedthattheconstantrateofcrossheadmovementtypeoftestleavesmuchtobedesiredfromatheoreticalstandpoint,thatwidedifferencesmayexistbetweenrateofcrossheadmovementandrateofstrainbetweengagemarksonthespecimen,andthatthetestingspeedsspecifieddisguiseimportanteffectscharacteristicofmaterialsintheplasticstate.Further,itisrealizedthatvariationsinthethicknessesoftestspecimens,whicharepermittedbytheseprocedures,producevariationsinthesurface-volumeratiosofsuchspecimens,andthatthesevariationsmayinfluencethetestresults.Hence,wheredirectlycomparableresultsaredesired,allsamplesshouldbeofequalthickness.Specialadditionaltestsshouldbeusedwheremoreprecisephysicaldataareneeded.

NOTE3—Thistestmethodmaybeusedfortestingphenolicmoldedresinorlaminatedmaterials.However,wherethesematerialsareusedaselectricalinsulation,suchmaterialsshouldbetestedinaccordancewithTestMethodsD229andTestMethodD651.

NOTE4—Fortensilepropertiesofresin-matrixcompositesreinforcedwithorientedcontinuousordiscontinuoushighmodulus>20-GPa[>3.03106-psi]fibers,testsshallbemadeinaccordancewithTestMethodD3039/D3039M.

1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.

2.ReferencedDocuments2.1ASTMStandards:2D229TestMethodsforRigidSheetandPlateMaterialsUsedforElectricalInsulation

D412TestMethodsforVulcanizedRubberandThermo-plasticElastomers—Tension

D618PracticeforConditioningPlasticsforTesting

D651TestMethodforTensileStrengthofMoldedElectri-calInsulatingMaterials

D882TestMethodsforTensilePropertiesofThinPlasticSheeting

D883TerminologyRelatingtoPlastics

D1822TestMethodforTensile-ImpactEnergytoBreakPlasticsandElectricalInsulatingMaterials

D3039/D3039MTestMethodforTensilePropertiesofPolymerMatrixCompositeMaterials

D4000ClassificationSystemforSpecifyingPlasticMate-rials

D4066ClassificationSystemforNylonInjectionandEx-trusionMaterials

D5947TestMethodsforPhysicalDimensionsofSolidPlasticSpecimens

E4PracticesforForceVerificationofTestingMachinesE83PracticeforVerificationandClassificationofExten-someter

E132TestMethodforPoisson’sRatioatRoomTempera-ture

E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod2.2ISOStandard:3ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.3AvailablefromAmericanNationalStandardsInstitute(ANSI),25W.43rdSt.,4thFloor,NewYork,NY10036.

21.4Testdataobtainedbythistestmethodarerelevantandappropriateforuseinengineeringdesign.

1.5ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninbracketsareforinformationonly.

ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlasticsandisthedirectresponsibilityofSubcommitteeD20.10onMechanicalProperties.CurrenteditionapprovedDecember1,2003.PublishedJanuary2004.Originallyapprovedin1941.Lastpreviouseditionapprovedin2002asD638-02a.

1*ASummaryofChangessectionappearsattheendofthisstandard.

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1

Not for Resale

ISO527-1DeterminationofTensileProperties

3.Terminology

3.1Definitions—DefinitionsoftermsapplyingtothistestmethodappearinTerminologyD883andAnnexA2.4.SignificanceandUse

4.1Thistestmethodisdesignedtoproducetensilepropertydataforthecontrolandspecificationofplasticmaterials.Thesedataarealsousefulforqualitativecharacterizationandforresearchanddevelopment.Formanymaterials,theremaybeaspecificationthatrequirestheuseofthistestmethod,butwithsomeproceduralmodificationsthattakeprecedencewhenadheringtothespecification.Therefore,itisadvisabletorefertothatmaterialspecificationbeforeusingthistestmethod.Table1inClassificationD4000liststheASTMmaterialsstandardsthatcurrentlyexist.

4.2Tensilepropertiesmayvarywithspecimenpreparationandwithspeedandenvironmentoftesting.Consequently,whereprecisecomparativeresultsaredesired,thesefactorsmustbecarefullycontrolled.

4.2.1Itisrealizedthatamaterialcannotbetestedwithoutalsotestingthemethodofpreparationofthatmaterial.Hence,whencomparativetestsofmaterialspersearedesired,thegreatestcaremustbeexercisedtoensurethatallsamplesarepreparedinexactlythesameway,unlessthetestistoincludetheeffectsofsamplepreparation.Similarly,forrefereepur-posesorcomparisonswithinanygivenseriesofspecimens,caremustbetakentosecurethemaximumdegreeofunifor-mityindetailsofpreparation,treatment,andhandling.

4.3Tensilepropertiesmayprovideusefuldataforplasticsengineeringdesignpurposes.However,becauseofthehighdegreeofsensitivityexhibitedbymanyplasticstorateofstrainingandenvironmentalconditions,dataobtainedbythistestmethodcannotbeconsideredvalidforapplicationsinvolv-ingload-timescalesorenvironmentswidelydifferentfromthoseofthistestmethod.Incasesofsuchdissimilarity,noreliableestimationofthelimitofusefulnesscanbemadeformostplastics.Thissensitivitytorateofstrainingandenviron-mentnecessitatestestingoverabroadload-timescale(includ-ingimpactandcreep)andrangeofenvironmentalconditionsiftensilepropertiesaretosufficeforengineeringdesignpur-poses.

NOTE5—Sincetheexistenceofatrueelasticlimitinplastics(asinmanyotherorganicmaterialsandinmanymetals)isdebatable,theproprietyofapplyingtheterm“elasticmodulus”initsquoted,generallyaccepteddefinitiontodescribethe“stiffness”or“rigidity”ofaplastichasbeenseriouslyquestioned.Theexactstress-straincharacteristicsofplasticmaterialsarehighlydependentonsuchfactorsasrateofapplicationofstress,temperature,previoushistoryofspecimen,etc.However,stress-straincurvesforplastics,determinedasdescribedinthistestmethod,almostalwaysshowalinearregionatlowstresses,andastraightlinedrawntangenttothisportionofthecurvepermitscalculationofanelasticmodulusoftheusuallydefinedtype.Suchaconstantisusefulifitsarbitrarynatureanddependenceontime,temperature,andsimilarfactorsarerealized.

4.4Poisson’sRatio—Whenuniaxialtensileforceisappliedtoasolid,thesolidstretchesinthedirectionoftheappliedforce(axially),butitalsocontractsinbothdimensionslateraltotheappliedforce.Ifthesolidishomogeneousandisotropic,

andthematerialremainselasticundertheactionoftheappliedforce,thelateralstrainbearsaconstantrelationshiptotheaxialstrain.Thisconstant,calledPoisson’sratio,isdefinedasthenegativeratioofthetransverse(negative)toaxialstrainunderuniaxialstress.

4.4.1Poisson’sratioisusedforthedesignofstructuresinwhichalldimensionalchangesresultingfromtheapplicationofforceneedtobetakenintoaccountandintheapplicationofthegeneralizedtheoryofelasticitytostructuralanalysis.

NOTE6—TheaccuracyofthedeterminationofPoisson’sratioisusuallylimitedbytheaccuracyofthetransversestrainmeasurementsbecausethepercentageerrorsinthesemeasurementsareusuallygreaterthanintheaxialstrainmeasurements.Sincearatioratherthananabsolutequantityismeasured,itisonlynecessarytoknowaccuratelytherelativevalueofthecalibrationfactorsoftheextensometers.Also,ingeneral,thevalueoftheappliedloadsneednotbeknownaccurately.

5.Apparatus

5.1TestingMachine—Atestingmachineoftheconstant-rate-of-crosshead-movementtypeandcomprisingessentiallythefollowing:

5.1.1FixedMember—Afixedoressentiallystationarymembercarryingonegrip.

5.1.2MovableMember—Amovablemembercarryingasecondgrip.

5.1.3Grips—Gripsforholdingthetestspecimenbetweenthefixedmemberandthemovablememberofthetestingmachinecanbeeitherthefixedorself-aligningtype.

5.1.3.1Fixedgripsarerigidlyattachedtothefixedandmovablemembersofthetestingmachine.Whenthistypeofgripisusedextremecareshouldbetakentoensurethatthetestspecimenisinsertedandclampedsothatthelongaxisofthetestspecimencoincideswiththedirectionofpullthroughthecenterlineofthegripassembly.

5.1.3.2Self-aligninggripsareattachedtothefixedandmovablemembersofthetestingmachineinsuchamannerthattheywillmovefreelyintoalignmentassoonasanyloadisappliedsothatthelongaxisofthetestspecimenwillcoincidewiththedirectionoftheappliedpullthroughthecenterlineofthegripassembly.Thespecimensshouldbealignedasper-fectlyaspossiblewiththedirectionofpullsothatnorotarymotionthatmayinduceslippagewilloccurinthegrips;thereisalimittotheamountofmisalignmentself-aligninggripswillaccommodate.

5.1.3.3Thetestspecimenshallbeheldinsuchawaythatslippagerelativetothegripsispreventedinsofaraspossible.Gripsurfacesthataredeeplyscoredorserratedwithapatternsimilartothoseofacoarsesingle-cutfile,serrationsabout2.4mm[0.09in.]apartandabout1.6mm[0.06in.]deep,havebeenfoundsatisfactoryformostthermoplastics.Finerserra-tionshavebeenfoundtobemoresatisfactoryforharderplastics,suchasthethermosettingmaterials.Theserrationsshouldbekeptcleanandsharp.Breakinginthegripsmayoccurattimes,evenwhendeepserrationsorabradedspecimensurfacesareused;othertechniquesmustbeusedinthesecases.Othertechniquesthathavebeenfounduseful,particularlywithsmooth-facedgrips,areabradingthatportionofthesurfaceofthespecimenthatwillbeinthegrips,andinterposingthin

piecesofabrasivecloth,abrasivepaper,orplastic,orrubber-coatedfabric,commonlycalledhospitalsheeting,betweenthespecimenandthegripsurface.No.80double-sidedabrasivepaperhasbeenfoundeffectiveinmanycases.Anopen-meshfabric,inwhichthethreadsarecoatedwithabrasive,hasalsobeeneffective.Reducingthecross-sectionalareaofthespeci-menmayalsobeeffective.Theuseofspecialtypesofgripsissometimesnecessarytoeliminateslippageandbreakageinthegrips.

5.1.4DriveMechanism—Adrivemechanismforimpartingtothemovablememberauniform,controlledvelocitywithrespecttothestationarymember,withthisvelocitytoberegulatedasspecifiedinSection8.

5.1.5LoadIndicator—Asuitableload-indicatingmecha-nismcapableofshowingthetotaltensileloadcarriedbythetestspecimenwhenheldbythegrips.Thismechanismshallbeessentiallyfreeofinertialagatthespecifiedrateoftestingandshallindicatetheloadwithanaccuracyof61%oftheindicatedvalue,orbetter.TheaccuracyofthetestingmachineshallbeverifiedinaccordancewithPracticesE4.

NOTE7—ExperiencehasshownthatmanytestingmachinesnowinuseareincapableofmaintainingaccuracyforaslongastheperiodsbetweeninspectionrecommendedinPracticesE4.Hence,itisrecommendedthateachmachinebestudiedindividuallyandverifiedasoftenasmaybefoundnecessary.Itfrequentlywillbenecessarytoperformthisfunctiondaily.

5.1.6Thefixedmember,movablemember,drivemecha-nism,andgripsshallbeconstructedofsuchmaterialsandinsuchproportionsthatthetotalelasticlongitudinalstrainofthesystemconstitutedbythesepartsdoesnotexceed1%ofthetotallongitudinalstrainbetweenthetwogagemarksonthetestspecimenatanytimeduringthetestandatanyloaduptotheratedcapacityofthemachine.

5.1.7CrossheadExtensionIndicator—Asuitableextensionindicatingmechanismcapableofshowingtheamountofchangeintheseparationofthegrips,thatis,crossheadmovement.Thismechanismshallbeessentiallyfreeofinertiallagatthespecifiedrateoftestingandshallindicatethecrossheadmovementwithanaccuracyof610%oftheindicatedvalue.

5.2ExtensionIndicator(extensometer)—Asuitableinstru-mentshallbeusedfordeterminingthedistancebetweentwodesignatedpointswithinthegagelengthofthetestspecimenasthespecimenisstretched.Forrefereepurposes,theextensom-etermustbesetatthefullgagelengthofthespecimen,asshowninFig.1.Itisdesirable,butnotessential,thatthisinstrumentautomaticallyrecordthisdistance,oranychangeinit,asafunctionoftheloadonthetestspecimenoroftheelapsedtimefromthestartofthetest,orboth.Ifonlythelatterisobtained,load-timedatamustalsobetaken.Thisinstrumentshallbeessentiallyfreeofinertiaatthespecifiedspeedoftesting.ExtensometersshallbeclassifiedandtheircalibrationperiodicallyverifiedinaccordancewithPracticeE83.

5.2.1Modulus-of-ElasticityMeasurements—Formodulus-of-elasticitymeasurements,anextensometerwithamaximumstrainerrorof0.0002mm/mm[in./in.]thatautomaticallyandcontinuouslyrecordsshallbeused.AnextensometerclassifiedbyPracticeE83asfulfillingtherequirementsofaB-2

classificationwithintherangeofuseformodulusmeasure-mentsmeetsthisrequirement.

5.2.2Low-ExtensionMeasurements—Forelongation-at-yieldandlow-extensionmeasurements(nominally20%orless),thesameaboveextensometer,attenuatedto20%exten-sion,maybeused.Inanycase,theextensometersystemmustmeetatleastClassC(PracticeE83)requirements,whichincludeafixedstrainerrorof0.001strainor61.0%oftheindicatedstrain,whicheverisgreater.

5.2.3High-ExtensionMeasurements—Formakingmea-surementsatelongationsgreaterthan20%,measuringtech-niqueswitherrornogreaterthan610%ofthemeasuredvalueareacceptable.

5.2.4Poisson’sRatio—Bi-axialextensometeroraxialandtransverseextensometerscapableofrecordingaxialstrainandtransversestrainsimultaneously.Theextensometersshallbecapableofmeasuringthechangeinstrainswithanaccuracyof1%oftherelevantvalueorbetter.

NOTE8—Straingagescanbeusedasanalternativemethodtomeasureaxialandtransversestrain;however,propertechniquesformountingstraingagesarecrucialtoobtainingaccuratedata.Consultstraingagesuppliersforinstructionandtraininginthesespecialtechniques.

5.3Micrometers—Apparatusformeasuringthewidthandthicknessofthetestspecimenshallcomplywiththerequire-mentsofTestMethodD5947.6.TestSpecimens

6.1Sheet,Plate,andMoldedPlastics:

6.1.1RigidandSemirigidPlastics—ThetestspecimenshallconformtothedimensionsshowninFig.1.TheTypeIspecimenisthepreferredspecimenandshallbeusedwheresufficientmaterialhavingathicknessof7mm[0.28in.]orlessisavailable.TheTypeIIspecimenmaybeusedwhenamaterialdoesnotbreakinthenarrowsectionwiththepreferredTypeIspecimen.TheTypeVspecimenshallbeusedwhereonlylimitedmaterialhavingathicknessof4mm[0.16in.]orlessisavailableforevaluation,orwherealargenumberofspecimensaretobeexposedinalimitedspace(thermalandenvironmentalstabilitytests,etc.).TheTypeIVspecimenshouldbeusedwhendirectcomparisonsarerequiredbetweenmaterialsindifferentrigiditycases(thatis,nonrigidandsemirigid).TheTypeIIIspecimenmustbeusedforallmaterialswithathicknessofgreaterthan7mm[0.28in.]butnotmorethan14mm[0.55in.].

6.1.2NonrigidPlastics—ThetestspecimenshallconformtothedimensionsshowninFig.1.TheTypeIVspecimenshallbeusedfortestingnonrigidplasticswithathicknessof4mm[0.16in.]orless.TheTypeIIIspecimenmustbeusedforallmaterialswithathicknessgreaterthan7mm[0.28in.]butnotmorethan14mm[0.55in.].

6.1.3ReinforcedComposites—Thetestspecimenforrein-forcedcomposites,includinghighlyorthotropiclaminates,shallconformtothedimensionsoftheTypeIspecimenshowninFig.1.

6.1.4Preparation—Testspecimensshallbepreparedbymachiningoperations,ordiecutting,frommaterialsinsheet,plate,slab,orsimilarform.Materialsthickerthan14mm[0.55

SpecimenDimensionsforThickness,T,mm[in.]ADimensions(seedrawings)7[0.28]orunderTypeI13[0.50]57[2.25]19[0.75]...165[6.5]50[2.00]...115[4.5]76[3.00]...TypeII6[0.25]57[2.25]19[0.75]...183[7.2]50[2.00]...135[5.3]76[3.00]...Over7to14[0.28to0.55],inclTypeIII19[0.75]57[2.25]29[1.13]...246[9.7]50[2.00]...115[4.5]76[3.00]...4[0.16]orunderTypeIVB6[0.25]33[1.30]19[0.75]...115[4.5]...25[1.00]65[2.5]J14[0.56]25[1.00]TypeVC,D3.18[0.125]9.53[0.375]...9.53[0.375]63.5[2.5]7.62[0.300]...25.4[1.0]12.7[0.5]...Tolerances60.5[60.02]B,C60.5[60.02]C+6.4[+0.25]+3.18[+0.125]nomax[nomax]60.25[60.010]C60.13[60.005]65[60.2]61[60.04]C61[60.04]W—WidthofnarrowsectionE,FL—LengthofnarrowsectionWO—Widthoverall,minGWO—Widthoverall,minGLO—Lengthoverall,minHG—GagelengthIG—GagelengthID—DistancebetweengripsR—RadiusoffilletRO—Outerradius(TypeIV)AThickness,T,shallbe3.260.4mm[0.1360.02in.]foralltypesofmoldedspecimens,andforotherTypesIandIIspecimenswherepossible.Ifspecimensaremachinedfromsheetsorplates,thickness,T,maybethethicknessofthesheetorplateprovidedthisdoesnotexceedtherangestatedfortheintendedspecimentype.Forsheetsofnominalthicknessgreaterthan14mm[0.55in.]thespecimensshallbemachinedto1460.4mm[0.5560.02in.]inthickness,forusewiththeTypeIIIspecimen.Forsheetsofnominalthicknessbetween14and51mm[0.55and2in.]approximatelyequalamountsshallbemachinedfromeachsurface.Forthickersheetsbothsurfacesofthespecimenshallbemachined,andthelocationofthespecimenwithreferencetotheoriginalthicknessofthesheetshallbenoted.Tolerancesonthicknesslessthan14mm[0.55in.]shallbethosestandardforthegradeofmaterialtested.BFortheTypeIVspecimen,theinternalwidthofthenarrowsectionofthedieshallbe6.0060.05mm[0.25060.002in.].ThedimensionsareessentiallythoseofDieCinTestMethodsD412.CTheTypeVspecimenshallbemachinedordiecuttothedimensionsshown,ormoldedinamoldwhosecavityhasthesedimensions.Thedimensionsshallbe:W=3.1860.03mm[0.12560.001in.],L=9.5360.08mm[0.37560.003in.],G=7.6260.02mm[0.30060.001in.],andR=12.760.08mm[0.50060.003in.].Theothertolerancesarethoseinthetable.DSupportingdataontheintroductionoftheLspecimenofTestMethodD1822astheTypeVspecimenareavailablefromASTMHeadquarters.RequestRR:D20-1038.EThewidthatthecenterWcshallbe+0.00mm,−0.10mm[+0.000in.,−0.004in.]comparedwithwidthWatotherpartsofthereducedsection.AnyreductioninWatthecentershallbegradual,equallyoneachsidesothatnoabruptchangesindimensionresult.FFormoldedspecimens,adraftofnotover0.13mm[0.005in.]maybeallowedforeitherTypeIorIIspecimens3.2mm[0.13in.]inthickness,andthisshouldbetakenintoaccountwhencalculatingwidthofthespecimen.ThusatypicalsectionofamoldedTypeIspecimen,havingthemaximumallowabledraft,couldbeasfollows:GOverallwidthsgreaterthantheminimumindicatedmaybedesirableforsomematerialsinordertoavoidbreakinginthegrips.HOveralllengthsgreaterthantheminimumindicatedmaybedesirableeithertoavoidbreakinginthegripsortosatisfyspecialtestrequirements.ITestmarksorinitialextensometerspan.JWhenself-tighteninggripsareused,forhighlyextensiblepolymers,thedistancebetweengripswilldependuponthetypesofgripsusedandmaynotbecriticalifmaintaineduniformoncechosen.

FIG.1TensionTestSpecimensforSheet,Plate,andMoldedPlastics

in.]mustbemachinedto14mm[0.55in.]foruseasTypeIIIspecimens.Specimenscanalsobepreparedbymoldingthematerialtobetested.

DIMENSIONSOFTUBESPECIMENS

StandardLength,L,NominalWallLengthofRadialTotalCalculated

ofSpecimentoBeThickness

Sections,Minimum2R.S.LengthofSpecimen

Usedfor-mm[3.5-in.]JawsAmm[in.]

0.79[1⁄32]

13.9[0.547]350[13.80]381[15]1.2[3⁄]17.0[0.670]354[13.92]381[15]1.6[1⁄16]19.6[0.773]356[14.02]381[15]2.4[3⁄32]24.0[0.946]361[14.20]381[15]3.2[1⁄8]27.7[1.091]3[14.34]381[15]4.8[3⁄16]33.9[1.333]370[14.58]381[15]6.4[1⁄4]39.0[1.536]376[14.79]400[15.75]7.9[5⁄16]43.5[1.714]380[14.96]400[15.75]9.5[3⁄8]47.6[1.873]384[15.12]400[15.75]11.1[7⁄16]51.3[2.019]388[15.27]400[15.75]12.7[1⁄2]

54.7[2.154]391[15.40]419[16.5]

AForotherjawsgreaterthanmm[3.5in.],thestandardlengthshallbeincreasedbytwicethelengthofthejawsminus178mm[7in.].Thestandardlengthpermitsaslippageofapproximately6.4to12.7mm[0.25to0.50in.]ineachjawwhilemaintainingthemaximumlengthofthejawgrip.

FIG.2DiagramShowingLocationofTubeTensionTest

SpecimensinTestingMachine

NOTE9—Testresultshaveshownthatforsomematerialssuchasglass

cloth,SMC,andBMClaminates,otherspecimentypesshouldbeconsideredtoensurebreakagewithinthegagelengthofthespecimen,asmandatedby7.3.

NOTE10—Whenpreparingspecimensfromcertaincompositelami-natessuchaswovenroving,orglasscloth,caremustbeexercisedincuttingthespecimensparalleltothereinforcement.Thereinforcementwillbesignificantlyweakenedbycuttingonabias,resultinginlowerlaminateproperties,unlesstestingofspecimensinadirectionotherthanparallelwiththereinforcementconstitutesavariablebeingstudied.

NOTE11—Specimenspreparedbyinjectionmoldingmayhavedifferenttensilepropertiesthanspecimenspreparedbymachiningordie-cuttingbecauseoftheorientationinduced.Thiseffectmaybemorepronouncedinspecimenswithnarrowsections.

6.2RigidTubes—ThetestspecimenforrigidtubesshallbeasshowninFig.2.Thelength,L,shallbeasshowninthetableinFig.2.Agrooveshallbemachinedaroundtheoutsideofthespecimenatthecenterofitslengthsothatthewallsectionaftermachiningshallbe60%oftheoriginalnominalwallthick-ness.Thisgrooveshallconsistofastraightsection57.2mm[2.25in.]inlengthwitharadiusof76mm[3in.]ateachendjoiningittotheoutsidediameter.Steelorbrassplugshavingdiameterssuchthattheywillfitsnuglyinsidethetubeandhavingalengthequaltothefulljawlengthplus25mm[1in.]shallbeplacedintheendsofthespecimenstopreventcrushing.Theycanbelocatedconvenientlyinthetubebyseparatingandsupportingthemonathreadedmetalrod.DetailsofplugsandtestassemblyareshowninFig.2.

6.3RigidRods—ThetestspecimenforrigidrodsshallbeasshowninFig.3.Thelength,L,shallbeasshowninthetableinFig.3.Agrooveshallbemachinedaroundthespecimenatthecenterofitslengthsothatthediameterofthemachinedportionshallbe60%oftheoriginalnominaldiameter.Thisgrooveshallconsistofastraightsection57.2mm[2.25in.]inlengthwitharadiusof76mm[3in.]ateachendjoiningittotheoutsidediameter.

6.4Allsurfacesofthespecimenshallbefreeofvisibleflaws,scratches,orimperfections.Marksleftbycoarsema-chiningoperationsshallbecarefullyremovedwithafinefileorabrasive,andthefiledsurfacesshallthenbesmoothedwithabrasivepaper(No.00orfiner).Thefinishingsandingstrokesshallbemadeinadirectionparalleltothelongaxisofthetestspecimen.Allflashshallberemovedfromamoldedspecimen,takinggreatcarenottodisturbthemoldedsurfaces.Inmachiningaspecimen,undercutsthatwouldexceedthedimensionaltolerancesshowninFig.1shallbescrupulouslyavoided.Careshallalsobetakentoavoidothercommonmachiningerrors.

6.5Ifitisnecessarytoplacegagemarksonthespecimen,thisshallbedonewithawaxcrayonorIndiainkthatwillnotaffectthematerialbeingtested.Gagemarksshallnotbescratched,punched,orimpressedonthespecimen.

6.6Whentestingmaterialsthataresuspectedofanisotropy,duplicatesetsoftestspecimensshallbeprepared,havingtheirlongaxesrespectivelyparallelwith,andnormalto,thesuspecteddirectionofanisotropy.7.NumberofTestSpecimens

7.1Testatleastfivespecimensforeachsampleinthecaseofisotropicmaterials.

DIMENSIONSOFRODSPECIMENS

NominalDiam-LengthofRadial

TotalCalculated

StandardLength,L,of

eterSections,2R.S.

Minimum

SpecimentoBeUsed

LengthofSpecimen

for-mm[31⁄2-in.]

JawsAmm[in.]

3.2[1⁄8]19.6[0.773]356[14.02]381[15]4.7[1⁄16]24.0[0.946]361[14.20]381[15]6.4[1⁄4]27.7[1.091]3[14.34]381[15]9.5[3⁄8]33.9[1.333]370[14.58]381[15]12.7[1⁄2]39.0[1.536]376[14.79]400[15.75]15.9[5⁄8]43.5[1.714]380[14.96]400[15.75]19.0[3⁄4]47.6[1.873]384[15.12]400[15.75]22.2[7⁄8]51.5[2.019]388[15.27]400[15.75]25.4[1]54.7[2.154]391[15.40]419[16.5]31.8[11⁄4]60.9[2.398]398[15.65]419[16.5]38.1[11⁄2]66.4[2.615]403[15.87]419[16.5]42.5[13⁄4]71.4[2.812]408[16.06]419[16.5]50.8[2]

76.0[2.993]412[16.24]432[17]

AForotherjawsgreaterthanmm[3.5in.],thestandardlengthshallbeincreasedbytwicethelengthofthejawsminus178mm[7in.].Thestandardlengthpermitsaslippageofapproximately6.4to12.7mm[0.25to0.50in.]ineachjawwhilemaintainingthemaximumlengthofthejawgrip.

FIG.3DiagramShowingLocationofRodTensionTestSpecimen

inTestingMachine

7.2Testtenspecimens,fivenormalto,andfiveparallelwith,theprincipleaxisofanisotropy,foreachsampleinthecaseofanisotropicmaterials.

7.3Discardspecimensthatbreakatsomeflaw,orthatbreakoutsideofthenarrowcross-sectionaltestsection(Fig.1,dimension“L”),andmakeretests,unlesssuchflawsconstituteavariabletobestudied.

NOTE12—Beforetesting,alltransparentspecimensshouldbeinspectedinapolariscope.Thosewhichshowatypicalorconcentratedstrainpatternsshouldberejected,unlesstheeffectsoftheseresidualstrainsconstituteavariabletobestudied.8.SpeedofTesting8.1Speedoftestingshallbetherelativerateofmotionofthegripsortestfixturesduringthetest.Therateofmotionofthedrivengriporfixturewhenthetestingmachineisrunningidlemaybeused,ifitcanbeshownthattheresultingspeedoftestingiswithinthelimitsofvariationallowed.8.2ChoosethespeedoftestingfromTable1.Determinethischosenspeedoftestingbythespecificationforthematerialbeingtested,orbyagreementbetweenthoseconcerned.Whenthespeedisnotspecified,usethelowestspeedshowninTable1forthespecimengeometrybeingused,whichgivesrupturewithin1⁄2to5-mintestingtime.8.3Modulusdeterminationsmaybemadeatthespeedselectedfortheothertensilepropertieswhentherecorderresponseandresolutionareadequate.8.4ThespeedoftestingforPoisson’sratiodeterminationshallbe5mm/min.9.Conditioning9.1Conditioning—Conditionthetestspecimensat2362°C[73.463.6°F]and5065%relativehumidityfornotlessthan40hpriortotestinaccordancewithProcedureAofPracticeD618,unlessotherwisespecifiedbycontractortherelevantASTMmaterialspecification.Referencepre-testcon-ditioning,tosettledisagreements,shallapplytolerancesof61°C[1.8°F]and62%relativehumidity.9.2TestConditions—Conductthetestsat2362°C[73.463.6°F]and5065%relativehumidity,unlessotherwisespecifiedbycontractortherelevantASTMmaterialspecifica-tion.Referencetestingconditions,tosettledisagreements,shallapplytolerancesof61°C[1.8°F]and62%relativehumidity.TABLE1DesignationsforSpeedofTestingANominalClassificationBSpecimenTypeSpeedofTesting,StrainCRateatmm/min[in./min]StartofTest,mm/mm·min[in./in.·min]RigidandSemirigidI,II,IIIrodsand5[0.2]625%0.1tubes50[2]610%1500[20]610%10IV5[0.2]625%0.1550[2]610%1.5500[20]610%15V1[0.05]625%0.110[0.5]625%1100[5]625%10NonrigidIII50[2]610%1500[20]610%10IV50[2]610%1.5500[20]610%15ASelectthelowestspeedthatproducesrupturein1⁄2to5minforthespecimengeometrybeingused(see8.2).BSeeTerminologyD883fordefinitions.CTheinitialrateofstrainingcannotbecalculatedexactlyfordumbbell-shapedspecimensbecauseofextension,bothinthereducedsectionoutsidethegagelengthandinthefillets.Thisinitialstrainratecanbemeasuredfromtheinitialslopeofthetensilestrain-versus-timediagram.

10.Procedure

10.1Measurethewidthandthicknessofeachspecimentothenearest0.025mm[0.001in.]usingtheapplicabletestmethodsinD5947.

TABLE2Modulus,106psi,forEightLaboratories,FiveMaterials

Mean

SrSRIrIRPolypropylene

0.2100.000.0710.0250.201Celluloseacetatebutyrate0.2460.01790.0350.0510.144Acrylic

0.4810.01790.0630.0510.144Glass-reinforcednylon1.170.05370.2170.1520.614Glass-reinforcedpolyester

1.39

0.04

0.266

0.253

0.753

10.1.1Measurethewidthandthicknessofflatspecimensatthecenterofeachspecimenandwithin5mmofeachendofthegagelength.

10.1.2Injectionmoldedspecimendimensionsmaybede-terminedbyactualmeasurementofonlyonespecimenfromeachsamplewhenithaspreviouslybeendemonstratedthatthespecimen-to-specimenvariationinwidthandthicknessislessthan1%.

10.1.3TakethewidthofspecimensproducedbyaTypeIVdieasthedistancebetweenthecuttingedgesofthedieinthenarrowsection.

10.1.4Measurethediameterofrodspecimens,andtheinsideandoutsidediametersoftubespecimens,tothenearest0.025mm[0.001in.]ataminimumoftwopoints90°apart;makethesemeasurementsalongthegrooveforspecimenssoconstructed.Useplugsintestingtubespecimens,asshowninFig.2.

10.2Placethespecimeninthegripsofthetestingmachine,takingcaretoalignthelongaxisofthespecimenandthegripswithanimaginarylinejoiningthepointsofattachmentofthegripstothemachine.Thedistancebetweentheendsofthegrippingsurfaces,whenusingflatspecimens,shallbeasindicatedinFig.1.Ontubeandrodspecimens,thelocationforthegripsshallbeasshowninFig.2andFig.3.Tightenthegripsevenlyandfirmlytothedegreenecessarytopreventslippageofthespecimenduringthetest,butnottothepointwherethespecimenwouldbecrushed.

10.3Attachtheextensionindicator.Whenmodulusisbeingdetermined,aClassB-2orbetterextensometerisrequired(see5.2.1).

NOTE13—Modulusofmaterialsisdeterminedfromtheslopeofthelinearportionofthestress-straincurve.Formostplastics,thislinearportionisverysmall,occursveryrapidly,andmustberecordedautomati-cally.Thechangeinjawseparationisnevertobeusedforcalculatingmodulusorelongation.

10.3.1Poisson’sRatioDetermination:

10.3.1.1ThemeasurementofPoisson’sRatioisoptionalandneedbedeterminedonlywhenrequested.Ifthetensilemodulusisdeterminedatatestspeedof5mm/min,itisacceptabletodeterminethePoisson’sratioatthesametimeasthetensilemodulus.

10.3.1.2Poisson’sRatioshallbedeterminedataspeedof5mm/min.Formaterialshavingadistinctlinearelasticregiononthestress-straincurvetheratioshallbedeterminedinthesameloadrangeasthatusedforthemeasurementofthemodulusof

elasticity.Ifthematerialdoesnotexhibitalinearstresstostrainrelationshiptheratioshallbedeterminedwithintheaxialstrainrangeof0.0005to0.0025mm/mm(0.05to0.25%).Iftheratioisdeterminedinthismanneritshallbenotedinthereportthataregionofproportionalityofstresstostrainwasnotevident.NOTE14—Asuitablemethodtojudgethedeterminationoflinearityofthestresstostraincurveisbymakingaseriesoftangentmodulusmeasurementsatdifferentaxialstrainlevels.Valuesequivalentateachstrainlevelindicatelinearity.Valuesshowingadownwardtrendwithincreasingstrainlevelindicatenonlinearity.10.3.1.3Attachthetransversestrainmeasuringdevice.Thetransversestrainmeasuringdevicemustcontinuouslymeasurethestrainsimultaneouslywiththeaxialstrainmeasuringdevice.TABLE3TensileStressatYield,103psi,forEightLaboratories,ThreeMaterialsMeanSrSRIrIRPolypropylene3.630.0220.1610.0620.456Celluloseacetatebutyrate5.010.0580.2270.10.2Acrylic10.40.0670.3170.1900.7TABLE4ElongationatYield,%,forEightLaboratories,ThreeMaterialsMeanSrSRIrIRCelluloseacetatebutyrate3.650.270.620.761.75Acrylic4.0.210.550.591.56Polypropylene8.790.455.861.2716.510.3.1.4Makesimultaneousmeasurementsofloadandstrainandrecordthedata.TheprecisionofthevalueofPoisson’sRatiowilldependonthenumberofdatapointsofaxialandtransversestraintaken.Itisrecommendedthatthedatacollectionrateforthetestbeaminimumof20pointspersecond.Thisisparticularlyimportantformaterialshavinganonlinearstresstostraincurve.10.4SetthespeedoftestingattheproperrateasrequiredinSection8,andstartthemachine.10.5Recordtheload-extensioncurveofthespecimen.10.6Recordtheloadandextensionattheyieldpoint(ifoneexists)andtheloadandextensionatthemomentofrupture.

NOTE15—Ifitisdesiredtomeasurebothmodulusandfailureproper-ties(yieldorbreak,orboth),itmaybenecessary,inthecaseofhighlyextensiblematerials,toruntwoindependenttests.Thehighmagnificationextensometernormallyusedtodeterminepropertiesuptotheyieldpointmaynotbesuitablefortestsinvolvinghighextensibility.Ifallowedtoremainattachedtothespecimen,theextensometercouldbepermanentlydamaged.Abroad-rangeincrementalextensometerorhand-ruletechniquemaybeneededwhensuchmaterialsaretakentorupture.

11.Calculation

11.1ToecompensationshallbemadeinaccordancewithAnnexA1,unlessitcanbeshownthatthetoeregionofthecurveisnotduetothetake-upofslack,seatingofthespecimen,orotherartifact,butratherisanauthenticmaterialresponse.

11.2TensileStrength—Calculatethetensilestrengthbydividingthemaximumloadinnewtons[pounds-force]bytheaverageoriginalcross-sectionalareainthegagelengthseg-mentofthespecimeninsquaremetres[squareinches].Expresstheresultinpascals[pounds-forcepersquareinch]andreportittothreesignificantfiguresastensilestrengthatyieldortensilestrengthatbreak,whichevertermisapplicable.Whenanominalyieldorbreakloadlessthanthemaximumispresentandapplicable,itmaybedesirablealsotocalculate,inasimilarmanner,thecorrespondingtensilestressatyieldortensilestressatbreakandreportittothreesignificantfigures(seeNoteA2.8).

11.3Elongationvaluesarevalidandarereportedincaseswhereuniformityofdeformationwithinthespecimengagelengthispresent.Elongationvaluesarequantitativelyrelevantandappropriateforengineeringdesign.Whennon-uniformdeformation(suchasnecking)occurswithinthespecimengagelengthnominalstrainvaluesarereported.Nominalstrainvaluesareofqualitativeutilityonly.11.4ModulusofElasticity—Calculatethemodulusofelas-ticitybyextendingtheinitiallinearportionoftheload-extensioncurveanddividingthedifferenceinstresscorre-spondingtoanysegmentofsectiononthisstraightlinebythecorrespondingdifferenceinstrain.Allelasticmodulusvaluesshallbecomputedusingtheaverageoriginalcross-sectionalareainthegagelengthsegmentofthespecimeninthecalculations.Theresultshallbeexpressedinpascals[pounds-forcepersquareinch]andreportedtothreesignificantfigures.11.5SecantModulus—Atadesignatedstrain,thisshallbecalculatedbydividingthecorrespondingstress(nominal)bythedesignatedstrain.Elasticmodulusvaluesarepreferableandshallbecalculatedwheneverpossible.However,formaterialswherenoproportionalityisevident,thesecantvalueshallbecalculated.DrawthetangentasdirectedinA1.3andFig.A1.2,andmarkoffthedesignatedstrainfromtheyieldpointwherethetangentlinegoesthroughzerostress.Thestresstobeusedinthecalculationisthendeterminedbydividingtheload-extensioncurvebytheoriginalaveragecross-sectionalareaof

FIG.4PlotofStrainsVersusLoadforDeterminationofPoisson’sRatio

11.3.1PercentElongation—Percentelongationisthechangeingagelengthrelativetotheoriginalspecimengagelength,expressedasapercent.Percentelongationiscalculatedusingtheapparatusdescribedin5.2.

11.3.1.1PercentElongationatYield—Calculatethepercentelongationatyieldbyreadingtheextension(changeingagelength)attheyieldpoint.Dividethatextensionbytheoriginalgagelengthandmultiplyby100.

11.3.1.2PercentElongationatBreak—Calculatetheper-centelongationatbreakbyreadingtheextension(changeingagelength)atthepointofspecimenrupture.Dividethatextensionbytheoriginalgagelengthandmultiplyby100.11.3.2NominalStrain—Nominalstrainisthechangeingripseparationrelativetotheoriginalgripseparationexpressedasapercent.Nominalstrainiscalculatedusingtheapparatusdescribedin5.1.7.

11.3.2.1Nominalstrainatbreak—Calculatethenominalstrainatbreakbyreadingtheextension(changeingripseparation)atthepointofrupture.Dividethatextensionbytheoriginalgripseparationandmultiplyby100.

thespecimen.

11.6Poisson’sRatio—Theaxialstrain,ea,indicatedbytheaxialextensometer,andthetransversestrain,et,indicatedbythetransverseextensometers,areplottedagainsttheappliedload,P,asshowninFig.4.

11.6.1Forthosematerialswherethereisproportionalityofstresstostrainanditispossibletodetermineamodulusofelasticity,astraightlineisdrawnthrougheachsetofpointswithintheloadrangeusedfordeterminationofmodulus,andtheslopesdea/dPanddet/dP,ofthoselinesaredetermined.Theuseofaleastsquaresmethodofcalculationwillreduceerrorsresultingfromdrawinglines.Poisson’sratio,µ,isthencalculatedasfollows:

µ52~det/dP!/~dea/dP!

(1)

where:

det=changeintransversestrain,dea=changeinaxialstrain,anddP=changeinappliedload;

or

µ52~det!/~dea!

(2)

Theerrorsthatmaybeintroducedbydrawingastraightlinethroughthepointscanbereducedbyapplyingtheleastsquaresmethod.

11.6.2Forthosematerialswherethereisnoproportionalityofstresstostrainevidentdeterminetheratioofdeonaxialstrainrangeof0.0005t/detoawhendea=0.002(based0.0025mm/mm)andaftertoecompensationhasbeenmade.

µ5det/0.002

(3)

11.7Foreachseriesoftests,calculatethearithmeticmeanofallvaluesobtainedandreportitasthe“averagevalue”fortheparticularpropertyinquestion.

11.8Calculatethestandarddeviation(estimated)asfollowsandreportittotwosignificantfigures:

s5=~(X22nX

¯2!/~n21!(4)

where:

s=estimatedstandarddeviation,X=valueofsingleobservation,n=numberofobservations,X

¯and

=arithmeticmeanofthesetofobservations.11.9SeeAnnexA1forinformationontoecompensation.

TABLE5TensileStrengthatBreak,103psi,forEight

Laboratories,FiveMaterialsAMean

SrSRIrIRPolypropylene

2.971.541.654.374.66Celluloseacetatebutyrate4.820.0580.1800.10.509Acrylic

9.090.4520.7511.272.13Glass-reinforcedpolyester20.80.2330.4370.6591.24Glass-reinforcednylon

23.6

0.277

0.698

0.784

1.98

ATensilestrengthandelongationatbreakvaluesobtainedforunreinforcedpropyleneplasticsgenerallyarehighlyvariableduetoinconsistenciesinneckingor“drawing”ofthecentersectionofthetestbar.Sincetensilestrengthandelongationatyieldaremorereproducibleandrelateinmostcasestothepracticalusefulnessofamoldedpart,theyaregenerallyrecommendedforspecificationpurposes.

TABLE6ElongationatBreak,%,forEightLaboratories,Five

MaterialsAMean

SrSRIrIRGlass-reinforcedpolyester3.680.202.330.5706.59Glass-reinforcednylon3.870.102.130.2836.03Acrylic

13.22.053.655.8010.3Celluloseacetatebutyrate14.11.876.625.2918.7Polypropylene

293.0

50.9

119.0

144.0

337.0

ATensilestrengthandelongationatbreakvaluesobtainedforunreinforcedpropyleneplasticsgenerallyarehighlyvariableduetoinconsistenciesinneckingor“drawing”ofthecentersectionofthetestbar.Sincetensilestrengthandelongationatyieldaremorereproducibleandrelateinmostcasestothepracticalusefulnessofamoldedpart,theyaregenerallyrecommendedforspecificationpurposes.

12.Report

12.1Reportthefollowinginformation:

12.1.1Completeidentificationofthematerialtested,includ-ingtype,source,manufacturer’scodenumbers,form,principaldimensions,previoushistory,etc.,

12.1.2Methodofpreparingtestspecimens,

TABLE7TensileYieldStrength,forTenLaboratories,EightMaterialsTestValuesExpressedinpsiUnitsMaterialSpeed,in./minAverageSrSRrRLDPE20154452.4.0146.6179.3LDPE201453.161.2148.7171.3LLDPE20187974.299.9207.8279.7LLDPE20179149.275.8137.9212.3LLDPE20290055.587.9155.4246.1LLDPE20173063.996.0178.9268.7HDPE24101196.1371.9549.11041.3HDPE23523175.9478.0492.41338.512.1.3Typeoftestspecimenanddimensions,12.1.4Conditioningprocedureused,12.1.5Atmosphericconditionsintestroom,12.1.6Numberofspecimenstested,12.1.7Speedoftesting,12.1.8Classificationofextensometersused.AdescriptionofmeasuringtechniqueandcalculationsemployedinsteadofaminimumClass-Cextensometersystem,12.1.9Tensilestrengthatyieldorbreak,averagevalue,andstandarddeviation,12.1.10Tensilestressatyieldorbreak,ifapplicable,averagevalue,andstandarddeviation,12.1.11Percentelongationatyield,orbreak,ornominalstrainatbreak,orallthree,asapplicable,averagevalue,andstandarddeviation,12.1.12Modulusofelasticityorsecantmodulus,averagevalue,andstandarddeviation,12.1.13Ifmeasured,Poisson’sratio,averagevalue,stan-darddeviation,andstatementofwhethertherewasproportion-alitywithinthestrainrange,12.1.14Dateoftest,and12.1.15RevisiondateofTestMethodD638.13.PrecisionandBias413.1Precision—Tables2-6arebasedonaround-robintestconductedin1984,involvingfivematerialstestedbyeightlaboratoriesusingtheTypeIspecimen,allofnominal0.125-in.thickness.Eachtestresultwasbasedonfiveindividualdeterminations.Eachlaboratoryobtainedtwotestresultsforeachmaterial.

13.1.1Tables7-10arebasedonaround-robintestcon-ductedbythepolyolefinsubcommitteein1988,involvingeightpolyethylenematerialstestedintenlaboratories.Foreachmaterial,allsamplesweremoldedatonesource,buttheindividualspecimenswerepreparedatthelaboratoriesthattestedthem.Eachtestresultwastheaverageoffiveindividualdeterminations.Eachlaboratoryobtainedthreetestresultsforeachmaterial.Datafromsomelaboratoriescouldnotbeusedforvariousreasons,andthisisnotedineachtable.

13.1.2Table11isbasedonarepeatabilitystudyinvolvingasinglelaboratory.Thetwomaterialsusedwereunfilledpolypropylenetypes.Measurementswereperformedbya

4SupportingdataareavailablefromASTMHeadquarters.RequestRR:D20-1125forthe1984roundrobinandRR:D20-1170forthe1988roundrobin.

TABLE8TensileYieldElongation,forEightLaboratories,Eight

Materials

MaterialLDPELDPELLDPELLDPELLDPELLDPEHDPEHDPE

TestSpeed,in./min20202020202022

ValuesExpressedinPercentUnits

Average17.014.615.716.611.715.29.279.63

TABLE11Poisson’sRatioRepeatabilityDataforOneLaboratoryandTwoPolypropyleneMaterialsMaterialsValuesExpressedasaDimensionlessRatiorAverageSr0.4120.0090.0260.4130.0110.0320.3910.0090.0260.3920.0100.028Sr1.26

1.021.371.591.271.271.401.23

SR3.162.382.853.302.882.592.842.75

r3.522.863.854.463.563.553.913.45

R8.846.677.979.248.087.257.947.71

PPPPPPPP#1#1#2#2ChordLeastSquaresChordLeastSquaresTABLE9TensileBreakStrength,forNineLaboratories,Six

Materials

MaterialLDPELDPELLDPELLDPELLDPELLDPE

TestSpeed,in./min202020202020

ValuesExpressedinpsiUnits

Average159217504379284016792660

Sr52.366.6127.178.634.3119.1

SR74.9102.9219.0143.547.0166.3

r146.4186.4355.8220.295.96333.6

R209.7288.1613.3401.8131.65.6

TABLE10TensileBreakElongation,forNineLaboratories,Six

Materials

MaterialLDPELDPELLDPELLDPELLDPELLDPE

TestSpeed,in./min202020202020

ValuesExpressedinPercentUnits

Average5675690.4803782

Sr31.561.525.76.6825.741.6

SR59.5.2113.811.7104.496.7

r88.2172.371.918.771.9116.6

R166.6249.7318.732.6292.5270.8

singletechnicianonasingleday.Eachtestresultisanindividualdetermination.TestingwasrunusingtwoTypeB-1extensometersfortransverseandaxialmeasurementsatatestspeedof5mm/min.

13.1.3InTables2-11,forthematerialsindicated,andfortestresultsthatderivedfromtestingfivespecimens:

13.1.3.1Sristhewithin-laboratorystandarddeviationoftheaverage;Ir=2.83Sr.(See13.1.3.3forapplicationofIr.)13.1.3.2SRisthebetween-laboratorystandarddeviationoftheaverage;IR=2.83SR.(See13.1.3.4forapplicationofIR.)13.1.3.3Repeatability—Incomparingtwotestresultsforthesamematerial,obtainedbythesameoperatorusingthesameequipmentonthesameday,thosetestresultsshouldbejudgednotequivalentiftheydifferbymorethantheIrvalueforthatmaterialandcondition.13.1.3.4Reproducibility—Incomparingtwotestresultsforthesamematerial,obtainedbydifferentoperatorsusingdiffer-entequipmentondifferentdays,thosetestresultsshouldbejudgednotequivalentiftheydifferbymorethantheIRvalueforthatmaterialandcondition.(Thisappliesbetweendifferentlaboratoriesorbetweendifferentequipmentwithinthesamelaboratory.)13.1.3.5Anyjudgmentinaccordancewith13.1.3.3and13.1.3.4willhaveanapproximate95%(0.95)probabilityofbeingcorrect.13.1.3.6Otherformulationsmaygivesomewhatdifferentresults.13.1.3.7Forfurtherinformationonthemethodologyusedinthissection,seePracticeE691.13.1.3.8Theprecisionofthistestmethodisverydependentupontheuniformityofspecimenpreparation,standardprac-ticesforwhicharecoveredinotherdocuments.13.2Bias—Therearenorecognizedstandardsonwhichtobaseanestimateofbiasforthistestmethod.14.Keywords14.1modulusofelasticity;percentelongation;plastics;Poisson’sratio;tensileproperties;tensilestrengthANNEXES

(MandatoryInformation)A1.TOECOMPENSATION

A1.1Inatypicalstress-straincurve(Fig.A1.1)thereisatoeregion,AC,thatdoesnotrepresentapropertyofthematerial.Itisanartifactcausedbyatakeupofslackandalignmentorseatingofthespecimen.Inordertoobtaincorrectvaluesofsuchparametersasmodulus,strain,andoffsetyieldpoint,thisartifactmustbecompensatedfortogivethecorrectedzeropointonthestrainorextensionaxis.

A1.2InthecaseofamaterialexhibitingaregionofHookean(linear)behavior(Fig.A1.1),acontinuationofthe

linear(CD)regionofthecurveisconstructedthroughthezero-stressaxis.Thisintersection(B)isthecorrectedzero-strainpointfromwhichallextensionsorstrainsmustbemeasured,includingtheyieldoffset(BE),ifapplicable.TheelasticmoduluscanbedeterminedbydividingthestressatanypointalongthelineCD(oritsextension)bythestrainatthesamepoint(measuredfromPointB,definedaszero-strain).A1.3Inthecaseofamaterialthatdoesnotexhibitanylinearregion(Fig.A1.2),thesamekindoftoecorrectionofthe

NOTE1—Somechartrecordersplotthemirrorimageofthisgraph.

FIG.A1.1MaterialwithHookeanRegion

NOTE1—Somechartrecordersplotthemirrorimageofthisgraph.

FIG.A1.2MaterialwithNoHookeanRegion

zero-strainpointcanbemadebyconstructingatangenttothemaximumslopeattheinflectionpoint(H8).ThisisextendedtointersectthestrainaxisatPointB8,thecorrectedzero-strainpoint.UsingPointB8aszerostrain,thestressatanypoint(G8)

onthecurvecanbedividedbythestrainatthatpointtoobtainasecantmodulus(slopeofLineB8G8).Forthosematerialswithnolinearregion,anyattempttousethetangentthroughtheinflectionpointasabasisfordeterminationofanoffsetyieldpointmayresultinunacceptableerror.

A2.DEFINITIONSOFTERMSANDSYMBOLSRELATINGTOTENSIONTESTINGOFPLASTICS

A2.1elasticlimit—thegreateststresswhichamaterialiscapableofsustainingwithoutanypermanentstrainremaininguponcompletereleaseofthestress.Itisexpressedinforceperunitarea,usuallymegapascals[pounds-forcepersquareinch].

NOTEA2.1—Measuredvaluesofproportionallimitandelasticlimitvarygreatlywiththesensitivityandaccuracyofthetestingequipment,eccentricityofloading,thescaletowhichthestress-straindiagramisplotted,andotherfactors.Consequently,thesevaluesareusuallyreplacedbyyieldstrength.

lusorYoung’smodulus).

NOTEA2.3—Thestress-strainrelationsofmanyplasticsdonotcon-formtoHooke’slawthroughouttheelasticrangebutdeviatetherefromevenatstresseswellbelowtheelasticlimit.Forsuchmaterialstheslopeofthetangenttothestress-straincurveatalowstressisusuallytakenasthemodulusofelasticity.Sincetheexistenceofatrueproportionallimitinplasticsisdebatable,theproprietyofapplyingtheterm“modulusofelasticity”todescribethestiffnessorrigidityofaplastichasbeenseriouslyquestioned.Theexactstress-straincharacteristicsofplasticmaterialsareverydependentonsuchfactorsasrateofstressing,temperature,previousspecimenhistory,etc.However,suchavalueisusefulifitsarbitrarynatureanddependenceontime,temperature,andotherfactorsarerealized.

A2.2elongation—theincreaseinlengthproducedinthegagelengthofthetestspecimenbyatensileload.Itisexpressedinunitsoflength,usuallymillimetres[inches].(Alsoknownasextension.)

NOTEA2.2—Elongationandstrainvaluesarevalidonlyincaseswhereuniformityofspecimenbehaviorwithinthegagelengthispresent.Inthecaseofmaterialsexhibitingneckingphenomena,suchvaluesareonlyofqualitativeutilityafterattainmentofyieldpoint.Thisisduetoinabilitytoensurethatneckingwillencompasstheentirelengthbetweenthegagemarkspriortospecimenfailure.

A2.5necking—thelocalizedreductionincrosssectionwhichmayoccurinamaterialundertensilestress.

A2.6offsetyieldstrength—thestressatwhichthestrainexceedsbyaspecifiedamount(theoffset)anextensionoftheinitialproportionalportionofthestress-straincurve.Itisexpressedinforceperunitarea,usuallymegapascals[pounds-forcepersquareinch].

NOTEA2.4—Thismeasurementisusefulformaterialswhosestress-straincurveintheyieldrangeisofgradualcurvature.Theoffsetyieldstrengthcanbederivedfromastress-straincurveasfollows(Fig.A2.1):OnthestrainaxislayoffOMequaltothespecifiedoffset.

DrawOAtangenttotheinitialstraight-lineportionofthestress-strain

A2.3gagelength—theoriginallengthofthatportionofthespecimenoverwhichstrainorchangeinlengthisdetermined.A2.4modulusofelasticity—theratioofstress(nominal)tocorrespondingstrainbelowtheproportionallimitofamaterial.Itisexpressedinforceperunitarea,usuallymegapascals[pounds-forcepersquareinch].(Alsoknownaselasticmodu-

FIG.A2.1OffsetYieldStrength

curve.

ThroughMdrawalineMNparalleltoOAandlocatetheintersectionofMNwiththestress-straincurve.

Thestressatthepointofintersectionristhe“offsetyieldstrength.”Thespecifiedvalueoftheoffsetmustbestatedasapercentoftheoriginalgagelengthinconjunctionwiththestrengthvalue.Example:0.1%offsetyieldstrength=...MPa[psi],oryieldstrengthat0.1%offset...MPa[psi].

A2.7percentelongation—theelongationofatestspecimenexpressedasapercentofthegagelength.

A2.8percentelongationatbreakandyield:

A2.8.1percentelongationatbreak—thepercentelongationatthemomentofruptureofthetestspecimen.

A2.8.2percentelongationatyield—thepercentelongationatthemomenttheyieldpoint(A2.22)isattainedinthetestspecimen.

A2.9percentreductionofarea(nominal)—thedifferencebetweentheoriginalcross-sectionalareameasuredatthepointofruptureafterbreakingandafterallretractionhasceased,expressedasapercentoftheoriginalarea.

A2.10percentreductionofarea(true)—thedifferencebetweentheoriginalcross-sectionalareaofthetestspecimenandtheminimumcross-sectionalareawithinthegagebound-ariesprevailingatthemomentofrupture,expressedasapercentageoftheoriginalarea.

A2.11Poisson’sRatio—Theabsolutevalueoftheratiooftransversestraintothecorrespondingaxialstrainresultingfromuniformlydistributedaxialstressbelowtheproportionallimitofthematerial.

A2.12proportionallimit—thegreateststresswhichamaterialiscapableofsustainingwithoutanydeviationfromproportionalityofstresstostrain(Hooke’slaw).Itisexpressedinforceperunitarea,usuallymegapascals[pounds-forcepersquareinch].

A2.13rateofloading—thechangeintensileloadcarriedbythespecimenperunittime.Itisexpressedinforceperunittime,usuallynewtons[pounds-force]perminute.Theinitial

rateofloadingcanbecalculatedfromtheinitialslopeoftheloadversustimediagram.

A2.14rateofstraining—thechangeintensilestrainperunittime.Itisexpressedeitherasstrainperunittime,usuallymetrespermetre[inchesperinch]perminute,orpercentelongationperunittime,usuallypercentelongationperminute.Theinitialrateofstrainingcanbecalculatedfromtheinitialslopeofthetensilestrainversustimediagram.

NOTEA2.5—Theinitialrateofstrainingissynonymouswiththerateofcrossheadmovementdividedbytheinitialdistancebetweencrossheadsonlyinamachinewithconstantrateofcrossheadmovementandwhenthespecimenhasauniformoriginalcrosssection,doesnot“neckdown,”anddoesnotslipinthejaws.

A2.15rateofstressing(nominal)—thechangeintensilestress(nominal)perunittime.Itisexpressedinforceperunitareaperunittime,usuallymegapascals[pounds-forcepersquareinch]perminute.Theinitialrateofstressingcanbecalculatedfromtheinitialslopeofthetensilestress(nominal)versustimediagram.

NOTEA2.6—Theinitialrateofstressingasdeterminedinthismannerhasonlylimitedphysicalsignificance.Itdoes,however,roughlydescribetheaveragerateatwhichtheinitialstress(nominal)carriedbythetestspecimenisapplied.Itisaffectedbytheelasticityandflowcharacteristicsofthematerialsbeingtested.Attheyieldpoint,therateofstressing(true)maycontinuetohaveapositivevalueifthecross-sectionalareaisdecreasing.

A2.16secantmodulus—theratioofstress(nominal)tocorrespondingstrainatanyspecifiedpointonthestress-straincurve.Itisexpressedinforceperunitarea,usuallymegapas-cals[pounds-forcepersquareinch],andreportedtogetherwiththespecifiedstressorstrain.

NOTEA2.7—Thismeasurementisusuallyemployedinplaceofmodu-lusofelasticityinthecaseofmaterialswhosestress-straindiagramdoesnotdemonstrateproportionalityofstresstostrain.

A2.17strain—theratiooftheelongationtothegagelengthofthetestspecimen,thatis,thechangeinlengthperunitoforiginallength.Itisexpressedasadimensionlessratio.

A2.17.1nominalstrainatbreak—thestrainatthemomentofrupturerelativetotheoriginalgripseparation.

A2.18tensilestrength(nominal)—themaximumtensilestress(nominal)sustainedbythespecimenduringatensiontest.Whenthemaximumstressoccursattheyieldpoint(A2.22),itshallbedesignatedtensilestrengthatyield.Whenthemaximumstressoccursatbreak,itshallbedesignatedtensilestrengthatbreak.

A2.19tensilestress(nominal)—thetensileloadperunitareaofminimumoriginalcrosssection,withinthegageboundaries,carriedbythetestspecimenatanygivenmoment.Itisexpressedinforceperunitarea,usuallymegapascals[pounds-forcepersquareinch].

NOTEA2.8—Theexpressionoftensilepropertiesintermsoftheminimumoriginalcrosssectionisalmostuniversallyusedinpractice.Inthecaseofmaterialsexhibitinghighextensibilityornecking,orboth(A2.16),nominalstresscalculationsmaynotbemeaningfulbeyondthe

yieldpoint(A2.22)duetotheextensivereductionincross-sectionalareathatensues.Undersomecircumstancesitmaybedesirabletoexpressthetensilepropertiesperunitofminimumprevailingcrosssection.Thesepropertiesarecalledtruetensileproperties(thatis,truetensilestress,etc.).

A2.20tensilestress-straincurve—adiagraminwhichvaluesoftensilestressareplottedasordinatesagainstcorre-spondingvaluesoftensilestrainasabscissas.

A2.21truestrain(seeFig.A2.2)isdefinedbythefollow-ingequationforeT:

eLT5

*LdL/L5lnL/L

(A2.1)

o

o

where:

dL=incrementofelongationwhenthedistancebetween

thegagemarksisL,

Lo=originaldistancebetweengagemarks,andL=distancebetweengagemarksatanytime.A2.22yieldpoint—thefirstpointonthestress-straincurveatwhichanincreaseinstrainoccurswithoutanincreaseinstress(Fig.A2.2).

NOTEA2.9—Onlymaterialswhosestress-straincurvesexhibitapointofzeroslopemaybeconsideredashavingayieldpoint.

NOTEA2.10—Somematerialsexhibitadistinct“break”ordiscontinu-ityinthestress-straincurveintheelasticregion.Thisbreakisnotayieldpointbydefinition.However,thispointmayproveusefulformaterialcharacterizationinsomecases.

A2.23yieldstrength—thestressatwhichamaterialexhib-itsaspecifiedlimitingdeviationfromtheproportionalityofstresstostrain.Unlessotherwisespecified,thisstresswillbethestressattheyieldpointandwhenexpressedinrelationtothetensilestrengthshallbedesignatedeithertensilestrengthatyieldortensilestressatyieldasrequiredinA2.18(Fig.A2.3).(Seeoffsetyieldstrength.)

A2.24Symbols—Thefollowingsymbolsmaybeusedfortheaboveterms:

FIG.A2.2IllustrationofTrueStrainEquation

FIG.A2.3TensileDesignations

Symbol

WDWLLoLuDLAAoDAAuATtDtsDssTsUsUTeDeeUeT%ElY.P.ETerm

Load

Incrementofload

DistancebetweengagemarksatanytimeOriginaldistancebetweengagemarks

DistancebetweengagemarksatmomentofruptureIncrementofdistancebetweengagemarks=elongationMinimumcross-sectionalareaatanytimeOriginalcross-sectionalarea

Incrementofcross-sectionalarea

Cross-sectionalareaatpointofrupturemeasuredafterbreakingspecimen

Cross-sectionalareaatpointofrupture,measuredatthemomentofruptureTime

IncrementoftimeTensilestress

IncrementofstressTruetensilestress

Tensilestrengthatbreak(nominal)Tensilestrengthatbreak(true)Strain

IncrementofstrainTotalstrain,atbreakTruestrain

PercentageelongationYieldpoint

Modulusofelasticity

A2.25Relationsbetweenthesevarioustermsmaybedefinedasfollows:

ssTsUsUTeeUeT%El========

W/AoW/AW/Ao(whereWisbreakingload)W/AT(whereWisbreakingload)DL/Lo=(L−Lo)/Lo(Lu−Lo)/LoL*LdL/L5lnL/Loo[(L−Lo)/Lo]3100=e3100

Percentreductionofarea(nominal)=[(Ao−Au)/Ao]3100Percentreductionofarea(true)=[(Ao−AT)/Ao]3100Rateofloading=DW/Dt

Rateofstressing(nominal)=Ds/D=(DW]/Ao)/DtRateofstraining=De/Dt=(DL/Lo)Dt

Forthecasewherethevolumeofthetestspecimendoesnotchangeduringthetest,thefollowingthreerelationshold:

sT5s~11e!5sL/LosUT5sU~11eU!5sULu/Lo

A5Ao/~11e!

(A2.2)

SUMMARYOFCHANGES

Thissectionidentifiesthelocationofselectedchangestothistestmethod.Fortheconvenienceoftheuser,CommitteeD20hashighlightedthosechangesthatmayimpacttheuseofthistestmethod.Thissectionmayalsoincludedescriptionsofthechangesorreasonsforthechanges,orboth.

D638-03:

(1)Revisedparagraphs5.3,10.1,11.2,and11.4toreflectuseofD5947andharmonizationwithISO527.(2)Revised8.4.

(3)Addednew10.3.1.1.

(4)Renumberedold10.3.1.1to10.3.1.2.(5)AddednewNote14.

(6)Renumberedold10.3.1.2to10.3.1.3.(7)Renumberedold10.3.1.3to10.3.1.4.(8)Revisedwordingofnew10.3.1.4.(9)RenumberedoldNote14to15.(10)Revised11.6.(11)Revised11.6.1.(12)Addednew11.6.2.

(13)Addednewequation(3).

(14)Renumberedoldequation(3)to(4).(15)Revised12.1.12.(16)Addednew12.1.13.(17)AddnewTable11.(18)Addnew13.1.2.

(19)Renumberedold13.1.2through13.1.2.8to13.1.3through13.1.3.8.

(20)AddedPoisson’sratioto14.1Keywords.

(21)AddednewA2.11.

(22)RenumberedA2.11throughA2.24toA2.12throughA2.25.

D638-02a:(1)Added5.1.7.

(2)Addednewtextfrom11.3to11.3.2.1.(3)Revised12.1.11.(4)AddedA2.16.1.D638-02:

(1)Revised9.1and9.2.D638-01:

(1)Modified7.3regardingconditionsforspecimendiscard.D638-00:

(1)Added11.1andrenumberedsubsequentsections.D638-99:

(1)Addedandclarifiedextensometerclassificationrequire-ments.D638-98:

(1)Revised10.3andadded12.1.8toclarifyextensometerusage.

(2)Added12.1.15.

(3)ReplacedreferencetoTestMethodsD374withTestMethodD5947in2.1and5.3.

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