1、Designation:D627210Standard Test Method forFlexural Properties of Unreinforced and Reinforced Plasticsand Electrical Insulating Materials by Four-Point Bending1This standard is issued under the fixed designation D6272;the number immediately following the designation indicates the year oforiginal ado
2、ption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers the determination of flexuralproperties of unreinforc
3、ed and reinforced plastics,includinghigh-modulus composites and electrical insulating materials inthe form of rectangular bars molded directly or cut from sheets,plates,or molded shapes.These test methods are generallyapplicable to rigid and semirigid materials.However,flexuralstrength cannot be det
4、ermined for those materials that do notbreak or that do not fail in the outer fibers.This test methodutilizes a four point loading system applied to a simplysupported beam.1.2 This test method may be used with two procedures:1.2.1 Procedure A,designed principally for materials thatbreak at comparati
5、vely small deflections.1.2.2 Procedure B,designed particularly for those materialsthat undergo large deflections during testing.1.2.3 ProcedureAshall be used for measurement of flexuralproperties,particularly flexural modulus,unless the materialspecification states otherwise.Procedure B may be used
6、formeasurement of flexural strength.1.3 Comparative tests may be run according to eitherprocedure,provided that the procedure is found satisfactory forthe material being tested.1.4 The values stated in SI units are to be regarded as thestandard.The values provided in parentheses are for informa-tion
7、 only.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1This te
8、st method is equivalent to ISO 14125(Method B).2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Ma
9、teri-alsD883 Terminology Relating to PlasticsD4000 Classification System for Specifying Plastic Materi-alsD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Exten-someter Syst
10、emsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:3ISO14125(MethodB)Fibre-ReinforcedPlasticCompositesDetermination of Flexural Properties3.Terminology3.1 Definitions:3.1.1 Definitions of terms applying to these test methodsappear in T
11、erminology D883 and Annex A2 of Test MethodD638.4.Summary of Test Method4.1 A bar of rectangular cross section rests on two supportsand is loaded at two points(by means of two loading noses),each an equal distance from the adjacent support point.Thedistance between the loading noses(the load span)is
12、 either onethird or one half of the support span(see Fig.1).A supportspan-to-depth ratio of 16:1 shall be used unless there is reasonto suspect that a larger span-to-depth ratio may be required,as1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsib
13、ility of Subcommittee D20.10 on Mechanical Properties.Current edition approved April 1,2010.Published April 2010.Originallyapproved in 1998.Last previous edition approved in 2008 as D6272-02(2008)1.DOI:10.1520/D6272-10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM
14、 Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes sect
15、ion appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 may be the case for certain laminated materials(see Section 7and Note 8 for guidance).4.2 The specimen is deflected until rupture occurs in theouter fi
16、bers or until the maximum fiber strain(see 12.7)of 5%is reached,whichever occurs first.5.Significance and Use5.1 Flexural properties determined by this test method areespecially useful for quality control and specification purposes.5.2 This test method may be more suited for those materialsthat do not fail within the strain limits imposed by Test MethodD790.The major difference between four point and three pointbending modes is the location of the maximum bendingmoment and maximum axial fiber st
