astm-d256-2010

1、Designation:D256–10StardTestMethodsfDeterminingtheIzodPendulumImpactResistanceofPlastics1ThisstardisissuedunderthefixeddesignationD256thenumberimmediatelyfollowingthedesignationindicatestheyearofiginaladoptioninthecaseof

2、revisiontheyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethelastrevisionreapproval.ThisstardhasbeenapprovedfusebyagenciesoftheDepartmentofDefense.1.Sc

3、ope1.1Thesetestmethodscoverthedeterminationoftheresistanceofplasticsto“stardized”(seeNote1)pendulumtypehammersmountedin“stardized”machinesinbreakingstardspecimenswithonependulumswing(seeNote2).Thestardtestsfthesetestmeth

4、odsrequirespecimensmadewithamillednotch(seeNote3).InTestMethodsACDthenotchproducesastressconcentrationthatincreasestheprobabilityofabrittleratherthanaductilefracture.InTestMethodEtheimpactresistanceisobtainedbyreversingt

5、henotchedspecimen180intheclampingvise.Theresultsofalltestmethodsarereptedintermsofenergyabsbedperunitofspecimenwidthperunitofcrosssectionalareaunderthenotch.(SeeNote4.)NOTE1—Themachineswiththeirpendulumtypehammershavebee

6、n“stardized”inthattheymustcomplywithcertainrequirementsincludingafixedheightofhammerfallthatresultsinasubstantiallyfixedvelocityofthehammeratthemomentofimpact.Howeverhammersofdifferentinitialenergies(producedbyvaryingthe

7、ireffectiveweights)arerecommendedfusewithspecimensofdifferentimpactresistance.Meovermanufacturersoftheequipmentarepermittedtousedifferentlengthsconstructionsofpendulumswithpossibledifferencesinpendulumrigiditiesresulting

8、.(SeeSection5.)Beawarethatotherdifferencesinmachinedesignmayexist.Thespecimensare“stardized”inthattheyarerequiredtohaveonefixedlengthonefixeddepthoneparticulardesignofmillednotch.Thewidthofthespecimensispermittedtovarybe

9、tweenlimits.NOTE2—Resultsgeneratedusingpendulumsthatutilizealoadcelltorecdtheimpactfcethusimpactenergymaynotbeequivalenttoresultsthataregeneratedusingmanuallydigitallyencodedtestersthatmeasuretheenergyremaininginthependu

10、lumafterimpact.NOTE3—ThenotchintheIzodspecimenservestoconcentratethestressminimizeplasticdefmationdirectthefracturetothepartofthespecimenbehindthenotch.Scatterinenergytobreakisthusreduced.Howeverbecauseofdifferencesinthe

11、elasticviscoelasticpropertiesofplasticsresponsetoagivennotchvariesamongmaterials.Ameasureofaplastic’s“notchsensitivity”maybeobtainedwithTestMethodDbycomparingtheenergiestobreakspecimenshavingdifferentradiiatthebaseofthen

12、otch.NOTE4—Cautionmustbeexercisedininterpretingtheresultsofthesestardtestmethods.Thefollowingtestingparametersmayaffecttestresultssignificantly:Methodoffabricationincludingbutnotlimitedtoprocessingtechnologymoldingcondit

13、ionsmolddesignthermaltreatmentsMethodofnotchingSpeedofnotchingtoolDesignofnotchingapparatusQualityofthenotchTimebetweennotchingtestTestspecimenthicknessTestspecimenwidthundernotchEnvironmentalconditioning.1.2Thevaluessta

14、tedinSIunitsaretoberegardedasstard.Thevaluesgiveninparenthesesarefinfmationonly.1.3Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Itistheresponsibilityoftheuserofthisstardtoestablishappropr

15、iatesafetyhealthpracticesdeterminetheapplicabilityofregulatylimitationspritouse.NOTE5—ThesetestmethodsresembleISO180:1993inregardtotitleonly.Thecontentsaresignificantlydifferent.2.ReferencedDocuments2.1ASTMStards:2D618Pr

16、acticefConditioningPlasticsfTestingD883TerminologyRelatingtoPlasticsD3641PracticefInjectionMoldingTestSpecimensofThermoplasticMoldingExtrusionMaterialsD4066ClassificationSystemfNylonInjectionExtrusionMaterials(PA)D5947Te

17、stMethodsfPhysicalDimensionsofSolidPlasticsSpecimens1ThesetestmethodsareunderthejurisdictionofASTMCommitteeD20onPlasticsarethedirectresponsibilityofSubcommitteeD20.10onMechanicalProperties.CurrenteditionapprovedMay12010.

18、PublishedJune2010.iginallyapprovedin1926.Lastpreviouseditionapprovedin2006asD25606a1.DOI:10.1520D025610.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCustomerServiceat.FAnnualBookofASTMStardsvolumeinfmati

19、onrefertothestard’sDocumentSummarypageontheASTMwebsite.1ASummaryofChangessectionappearsattheendofthisstard.Copyright?ASTMInternational100BarrHarbDrivePOBoxC700WestConshohockenPA194282959UnitedStates.5.3Theenergylostbythe

20、pendulumduringthebreakageofthespecimenisthesumofthefollowing:5.3.1Energytoinitiatefractureofthespecimen5.3.2Energytopropagatethefractureacrossthespecimen5.3.3Energytothrowthefreeend(ends)ofthebrokenspecimen(“tosscrection

21、”)5.3.4Energytobendthespecimen5.3.5Energytoproducevibrationinthependulumarm5.3.6Energytoproducevibrationhizontalmovementofthemachineframebase5.3.7Energytoovercomefrictioninthependulumbearingintheindicatingmechanismtoover

22、comewindage(pendulumairdrag)5.3.8Energytoindentdefmplasticallythespecimenatthelineofimpact5.3.9Energytoovercomethefrictioncausedbytherubbingofthestriker(otherpartofthependulum)overthefaceofthebentspecimen.5.4Frelativelyb

23、rittlematerialsfwhichfracturepropagationenergyissmallincomparisonwiththefractureinitiationenergytheindicatedimpactenergyabsbedisfallpracticalpurposesthesumoffacts5.3.15.3.3.Thetosscrection(see5.3.3)mayrepresentaverylarge

24、fractionofthetotalenergyabsbedwhentestingrelativelydensebrittlematerials.TestMethodCshallbeusedfmaterialsthathaveanIzodimpactresistanceoflessthan27Jm(0.5ftlbfin.).(SeeAppendixX4foptionalunits.)ThetosscrectionobtainedinTe

25、stMethodCisonlyanapproximationofthetosserrsincetherotationalrectilinearvelocitiesmaynotbethesameduringtheretossofthespecimenasftheiginaltossbecausestedstressesinthespecimenmayhavebeenreleasedaskiicenergyduringthespecimen

26、fracture.5.5Ftoughductilefiberfilledclothlaminatedmaterialsthefracturepropagationenergy(see5.3.2)maybelargecomparedtothefractureinitiationenergy(see5.3.1).Whentestingthesematerialsfacts(see5.3.25.3.55.3.9)canbecomequites

27、ignificantevenwhenthespecimenisaccuratelymachinedpositionedthemachineisingoodconditionwithadequatecapacity.(SeeNote7.)Bending(see5.3.4)indentationlosses(see5.3.8)maybeappreciablewhentestingsoftmaterials.NOTE7—Althoughthe

28、framebaseofthemachineshouldbesufficientlyrigidmassivetohletheenergiesoftoughspecimenswithoutmotionexcessivevibrationthedesignmustensurethatthecenterofpercussionbeatthecenterofstrike.Locatingthestrikerpreciselyatthecenter

29、ofpercussionreducesvibrationofthependulumarmwhenusedwithbrittlespecimens.Howeversomelossesduetopendulumarmvibrationtheamountvaryingwiththedesignofthependulumwilloccurwithtoughspecimensevenwhenthestrikerisproperlyposition

30、ed.5.6Inawelldesignedmachineofsufficientrigiditymassthelossesduetofacts5.3.65.3.7shouldbeverysmall.Vibrationallosses(see5.3.6)canbequitelargewhenwidespecimensoftoughmaterialsaretestedinmachinesofinsufficientmassnotsecure

31、lyfastenedtoaheavybase.5.7Withsomematerialsacriticalwidthofspecimenmaybefoundbelowwhichspecimenswillappearductileasevidencedbyconsiderabledrawingneckingdownintheregionbehindthenotchbyarelativelyhighenergyabsptionabovewhi

32、chtheywillappearbrittleasevidencedbylittlenodrawingdownneckingbyarelativelylowenergyabsption.Sincethesemethodspermitavariationinthewidthofthespecimenssincethewidthdictatesfmanymaterialswhetherabrittlelowenergybreakaducti

33、lehighenergybreakwilloccuritisnecessarythatthewidthbestatedinthespecificationcoveringthatmaterialthatthewidthbereptedalongwiththeimpactresistance.Inviewoftheprecedingoneshouldnotmakecomparisonsbetweendatafromspecimenshav

34、ingwidthsthatdifferbymethanafewmils.5.8Thetypeoffailurefeachspecimenshallberecdedasoneofthefourcategieslistedasfollows:C=CompleteBreak—Abreakwherethespecimenseparatesintotwomepieces.H=HingeBreak—Anincompletebreaksuchthat

35、onepartofthespecimencannotsupptitselfabovethehizontalwhentheotherpartisheldvertically(lessthan90includedangle).P=PartialBreak—Anincompletebreakthatdoesnotmeetthedefinitionfahingebreakbuthasfracturedatleast90%ofthedistanc

36、ebetweenthevertexofthenotchtheoppositeside.NB=NonBreak—Anincompletebreakwherethefractureextendslessthan90%ofthedistancebetweenthevertexofthenotchtheoppositeside.Ftoughmaterialsthependulummaynothavetheenergynecessarytocom

37、pletethebreakingoftheextremefiberstossthebrokenpiecepieces.Resultsobtainedfrom“nonbreak”specimensshallbeconsideredadeparturefromstandardshallnotbereptedasastardresult.Impactresistancecannotbedirectlycomparedfanytwomateri

38、alsthatexperiencedifferenttypesoffailureasdefinedinthetestmethodbythiscode.Averagesreptedmustlikewisebederivedfromspecimenscontainedwithinasinglefailurecategy.Thislettercodeshallsuffixthereptedimpactidentifyingthetypesof