ASTMD790-2017Word格式.docx
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ASTMD790-2017Word格式.docx
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)indicatesaneditorialchangesincethelastrevisionorreapproval.
本标准以固定名称D790发布;
紧接指定的数字表示原始采纳的年份,或者在修订的情况下是最近一次修订的年份。
括号中的数字表示上次重新批准的年份。
上标epsilon('
)表示自上次修订或重新批准以来的编辑更改。
ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.
该标准已被美国国防部的机构批准使用。
14
CopyrightASTMInternational
ProvidedbyIHSMarkitunderlicensewithASTM
NoreproductionornetworkingpermittedwithoutlicensefromIHS
Licensee=JilinInstituteofStandardization/5993190001,User=BZYWXS@126.COM,BZYNotforResale,06/19/201800:
44:
21MDT
1.Scope*范围
1.1Thesetestmethodsareusedtodeterminetheflexuralpropertiesofunreinforcedandreinforcedplastics,includinghighmoduluscompositesandelectricalinsulatingmaterialsutilizingathree-pointloadingsystemtoapplyaloadtoasimplysupportedbeam(specimen).Themethodisgenerallyapplicabletobothrigidandsemi-rigidmaterials,butflexuralstrengthcannotbedeterminedforthosematerialsthatdonotbreakoryieldintheoutersurfaceofthetestspecimenwithinthe5.0%strainlimit.
这些测试方法用于确定未增强和增强塑料的弯曲性能,包括高模量复合材料和电绝缘材料,利用三点加载系统将载荷施加到简支梁(试样)上。
该方法通常适用于刚性和半刚性材料,但对于在5.0%应变极限内在试样外表面不破裂或屈服的那些材料,不能确定弯曲强度。
1.2Testspecimensofrectangularcrosssectionareinjectionmoldedor,cutfrommoldedorextrudedsheetsorplates,orcutfrommoldedorextrudedshapes.Specimensmustbesolidanduniformlyrectangular.Thespecimenrestsontwosupportsandisloadedbymeansofaloadingnosemidwaybetweenthesupports.
1.2矩形横截面的试样是注塑成型的,或者是从模塑或挤出的板材或板材上切割下来的,或者是从模塑或挤压形状切割而成。
标本必须是实心且均匀的矩形。
样品放在两个支撑上,并通过支撑件中间的装载鼻加载。
1.3Measuredeflectioninoneoftwoways;
usingcrossheadpositionoradeflectometer.Pleasenotethatstudieshaveshownthatdeflectiondataobtainedwithadeflectometerwilldifferfromdataobtainedusingcrossheadposition.Themethodofdeflectionmeasurementshallbereported.
NOTE1—Requirementsforqualitycontrolinproductionenvironmentsareusuallymetbymeasuringdeflectionusingcrossheadposition.However,moreaccuratemeasurementmaybeobtainedbyusingandeflectionindicatorsuchasadeflectometer.
NOTE2—Materialsthatdonotrupturebythemaximumstrainallowedunderthistestmethodmaybemoresuitedtoa4-pointbendtest.Thebasicdifferencebetweenthetwotestmethodsisinthelocationofthemaximumbendingmomentandmaximumaxialfiberstresses.Themaximumaxialfiberstressesoccuronalineundertheloadingnosein3-pointbendingandovertheareabetweentheloadingnosesin4-pointbending.Afour-pointloadingsystemmethodcanbefoundinTestMethodD6272.
1.4ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesprovidedinparenthesesareforinforma-tiononly.
1.5Thetextofthisstandardreferencesnotesandfootnotesthatprovideexplanatorymaterial.Thesenotesandfootnotes(excludingthoseintablesandfigures)shallnotbeconsideredasrequirementsofthestandard.
1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.
NOTE3—ThisstandardandISO178addressthesamesubjectmatter,butdifferintechnicalcontent.
1.7Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.
2.ReferencedDocuments
2.1ASTMStandards:
2
D618PracticeforConditioningPlasticsforTestingD638TestMethodforTensilePropertiesofPlasticsD883TerminologyRelatingtoPlastics
D4000ClassificationSystemforSpecifyingPlasticMateri-als
D4101SpecificationforPolypropyleneInjectionandExtru-sionMaterials
D5947TestMethodsforPhysicalDimensionsofSolidPlasticsSpecimens
--`,`,,,,,`,,,``,,,````,,,`,,``,-`-`,,`,,`,`,,`---
D6272TestMethodforFlexuralPropertiesofUnreinforcedandReinforcedPlasticsandElectricalInsulatingMateri-alsbyFour-PointBending
E4PracticesforForceVerificationofTestingMachinesE83PracticeforVerificationandClassificationofExten-
someterSystems
1ThesetestmethodsareunderthejurisdictionofASTMCommitteeD20onPlasticsandarethedirectresponsibilityofSubcommitteeD20.10onMechanicalProperties.
CurrenteditionapprovedJuly1,2017.PublishedJuly2017.Originallyapprovedin1970.Lastpreviouseditionapprovedin2015asD790–15ɛ2.DOI:
10.1520/D0790-17.
2ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.
*ASummaryofChangessectionappearsattheendofthisstandard
Copyright©
ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959.UnitedStates
D790−17
E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod
E2309PracticesforVerificationofDisplacementMeasuringSystemsandDevicesUsedinMaterialTestingMachines
2.2ISOStandard:
3
ISO178Plastics—DeterminationofFlexuralProperties
3.Terminology
3.1Definitions—DefinitionsoftermsapplyingtothesetestmethodsappearinTerminologyD883andAnnexA2ofTestMethodD638.
4.SummaryofTestMethod
4.1Atestspecimenofrectangularcrosssectionrestsontwosupportsinaflat-wisepositionandisloadedbymeansofaloadingnoselocatedmidwaybetweenthesupports.Unlesstestingcertainlaminatedmaterials(see7forguidance),asupportspan-to-depth(ofspecimen)ratio16:
1shallbeused.Thespecimenisdeflecteduntilruptureoccursintheoutersurfaceofthetestspecimenoruntilamaximumstrain(see5.1.6)of5.0%isreached,whicheveroccursfirst.
4.2ProcedureAisdesignedprincipallyformaterialsthatbreakatcomparativelysmalldeflectionsanditshallbeusedformeasurementofflexuralproperties,particularlyflexuralmodulus,unlessthematerialspecificationstatesotherwise.ProcedureAemploysastrainrateof0.01mm/mm/min(0.01in./in./min)andisthepreferredprocedureforthistestmethod.
4.3ProcedureBisdesignedprincipallyforthosematerialsthatdonotbreakoryieldintheoutersurfaceofthetestspecimenwithinthe5.0%strainlimitwhenProcedureAconditionsareused.ProcedureBemploysastrainrateof0.10mm/mm/min(0.10in./in./min).
4.4TypeItestsutilizecrossheadpositionfordeflectionmeasurement.
4.5TypeIItestsutilizeaninstrument(deflectometer)fordeflectionmeasurement.
4.6Theprocedureusedandtesttypeshallbereported
NOTE4—Comparativetestsmayberuninaccordancewitheitherprocedure,providedthattheprocedureisfoundsatisfactoryforthematerialbeingtested.TangentmodulusdataobtainedbyProcedureAtendstoexhibitlowerstandarddeviationsthancomparableresultsobtainedbymeansofProcedureB.
5.SignificanceandUse
5.1Flexuralpropertiesasdeterminedbythistestmethodareespeciallyusefulforqualitycontrolandspecificationpurposes.Theyinclude:
5.1.1FlexuralStress(σf)—Whenahomogeneouselasticmaterialistestedinflexureasasimplebeamsupportedattwopointsandloadedatthemidpoint,themaximumstressintheoutersurfaceofthetestspecimenoccursatthemidpoint.Flexuralstressiscalculatedforanypointontheload-deflectioncurveusingequation(Eq3)inSection12(seeNotes5and6).
NOTE5—Eq3appliesstrictlytomaterialsforwhichstressislinearly
3AvailablefromAmericanNationalStandardsInstitute(ANSI),25W.43rdSt.,4thFloor,NewYork,NY10036,http:
//www.ansi.org.
proportionaltostrainuptothepointofruptureandforwhichthestrainsaresmall.Sincethisisnotalwaysthecase,aslighterrorwillbeintroducedifEq3isusedtocalculatestressformaterialsthatarenottrueHookeanmaterials.Theequationisvalidforobtainingcomparisondataandforspecificationpurposes,butonlyuptoamaximumfiberstrainof5%intheoutersurfaceofthetestspecimenforspecimenstestedbytheproceduresdescribedherein.
NOTE6—Whentestinghighlyorthotropiclaminates,themaximumstressmaynotalwaysoccurintheoutersurfaceofthetestspecimen.4Laminatedbeamtheorymustbeappliedtodeterminethemaximumtensilestressatfailure.IfEq3isusedtocalculatestress,itwillyieldanapparentstrengthbasedonhomogeneousbeamtheory.Thisapparentstrengthishighlydependentontheply-stackingsequenceofhighlyorthotropiclaminates.
5.1.2FlexuralStressforBeamsTestedatLargeSupportSpans(σf)—Ifsupportspan-to-depthratiosgreaterthan16to1areusedsuchthatdeflectionsinexcessof10%ofthesupportspanoccur,the
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