ASTMD790-2017.docx
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ASTMD790-2017.docx
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ThisinternationalstandardwasdevelopedinaccordancewithinternationallyrecognizedprinciplesonstandardizationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecommendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.
Designation:
D790−17
StandardTestMethodsfor
FlexuralPropertiesofUnreinforcedandReinforcedPlasticsandElectricalInsulatingMaterials1
非增强和增强塑料和电绝缘材料的弯曲性能的标准试验方法
ThisstandardisissuedunderthefixeddesignationD790;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)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
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D6272TestMethodfor
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