ASTMD790-2017Word格式文档下载.docx

ASTMD790-2017Word格式文档下载.docx

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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