1、Designation: D6272 10D6272 17Standard 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 ofo
2、riginal adoption 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 flexural prope
3、rties of unreinforced and reinforced plastics, includinghigh-modulus composites and electrical insulating materials in the form of rectangular bars molded directly or cut from sheets,plates, or molded shapes. These test methods are generally applicable to rigid and semirigid materials. However, flex
4、ural strengthcannot be determined for those materials that do not break or that do not fail in the outer fibers. This test method utilizes a fourpoint loading system applied to a simply supported beam.1.2 This test method may be used with two procedures: describes two procedures (Procedure A and Pro
5、cedure B), the selectionof which depends on the behavior of the sample to be tested as explained below:1.2.1 Procedure A, designed principally for materials that break at comparatively small deflections.1.2.2 Procedure B, designed particularly for those materials that undergo large deflections durin
6、g testing.1.2.1 Procedure A, ProcedureAdesigned principally for materials that break at comparatively small deflections. It shall be usedfor measurement of flexural properties, particularly flexural modulus, unless the material specification states otherwise. ProcedureB may be used for measurement o
7、f flexural strength.1.2.2 Procedure B, designed particularly for those materials that undergo large deflections during testing. It is suitable formeasurement of flexural strength.1.3 Comparative tests may are permitted to be run according to either procedure, provided that the procedure is foundsati
8、sfactory for the material being tested.1.4 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
9、of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.NOTE 1This test method is equivalent to ISO 14125 (Method B).similar to ISO 14125, Method B. However, ISO 14125, Method B specifies onlya load span
10、of 13 the support span whereas D6272 also permits a load span of 12 the support span. For this reason and other differences in technical content,exercise extreme care if attempting to compare results between the two test methods.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioni
11、ng Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating MaterialsD883 Terminology Relating to PlasticsD4000 Classification System for Specifying Plastic MaterialsD5947 Test M
12、ethods for Physical Dimensions of Solid Plastics SpecimensE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Extensometer SystemsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method1 This test method
13、 is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved April 1, 2010March 1, 2017. Published April 2010March 2017. Originally approved in 1998. Last previous edition approved in 20082010 a
14、sD6272 - 02D6272 - 10.(2008) 1. DOI: 10.1520/D6272-10.10.1520/D6272-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the AST
15、M website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult
16、 prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
17、 19428-2959. United States12.2 ISO Standard:3ISO 14125 (Method B) Fibre-Reinforced Plastic CompositesDetermination of Flexural Properties3. Terminology3.1 Definitions:3.1.1 Definitions of terms applying to these test methods appear in Terminology D883 and Annex A2 of Test Method D638.4. Summary of T
18、est Method4.1 A bar of rectangular cross section rests on two supports and is loaded at two points (by means of two loading noses), eachan equal distance from the adjacent support point. The distance between the loading noses (the load span) is either one third orone half of the support span (see Fi
19、g. 1). A support span-to-depth ratio of 16:1 shall be used unless there is reason to suspect thata larger span-to-depth ratio may be is required, as may be the case for such as with certain laminated materials (see Section 7 andNote 8for guidance).4.2 The specimen is deflected until rupture occurs i
20、n the outer fibers or until the maximum fiber strain (see 12.712.8) of 5 %is reached, whichever occurs first.5. Significance and Use5.1 Flexural properties determined by this test method are especially useful for quality control and specification purposes.5.2 This test method may be more suited is r
21、ecommended for those materials that do not fail within the strain limits imposedby Test Method D790. The major difference between four point and three point bending modes is the location of the maximumbending moment and maximum axial fiber stress. In four point bending the maximum axial fiber stress
22、 is uniformly distributedbetween the loading noses. In three point bending the maximum axial fiber stress is located immediately under the loading nose.5.3 Flexural properties may vary with specimen depth, temperature, atmospheric conditions, and the difference in rate ofstraining specified in Proce
23、dures A and B.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.FIG. 1 Loading DiagramD6272 1725.4 Before proceeding with this test method, reference should be made to the specification of the material being tested.Any te
24、stspecimen preparation, conditioning, dimensions, or testing parameters covered in the material specification, or both, shall takeprecedence over those mentioned in this test method. If there are no material specifications, then these default conditions apply.Table 1 in Classification D4000 lists th
25、e ASTM materials standards that currently exist.6. Apparatus6.1 Testing MachineA properly calibrated testing machine that can be operated capable of operating at constant rates ofcrosshead motion over the range indicated, and in which the error in the load measuring system shall not exceed 6 1 % ofm
26、aximum load expected to be measured. It shall be equipped with a deflection measuring device. The stiffness of the testingmachine shall be such that the total elastic deformation of the system does not exceed 1 % of the total deflection of the testspecimen during testing, or appropriate corrections
27、shall be made. The load indicating mechanism shall be essentially free frominertial lag at the crosshead rate used. The accuracy of the testing machine shall be verified in accordance with Practices E4.6.2 Loading Noses and SupportsThe loading noses and supports shall have cylindrical surfaces. In o
28、rder to avoid excessiveindentation, or failure due to stress concentration directly under the loading noses, the radii of the loading noses and supports shallbe 5.0 6 0.1 mm (0.197 6 0.004 in.) unless otherwise specified or agreed upon between the interested parties. When other loadingnoses and supp
29、orts are used they must comply with the following requirements: they shall be at least 3.2 mm (18 in.) for allspecimens, and for specimens 3.2 mm (18 in.) or greater in depth, the radius of the supports may be up to shall not exceed 1.6 timesthe specimen depth. They shall be this large if significan
30、t indentation or compressive failure occurs. The arc of the loading nosesin contact with the specimen shall be sufficiently large to prevent contact of the specimen with the sides of the noses (see Fig. 2).NOTE 2Test data have shown that the loading noses and support dimensions can influence the fle
31、xural modulus and flexural strength values. Theloading noses dimension has the greater influence. Dimensions of loading noses and supports must be specified for are requirements for the materialspecifications.6.3 Deflection Measuring DeviceA properly calibrated device to measure the deflection of th
32、e beam at the common center ofthe loading span, that meets or exceeds Practice E83, Class C, B-2 for modulus, and Class C for other strain measurements, shallbe used. The device shall automatically and continuously record the deflection during the test.6.4 MicrometersSuitable micrometers for measuri
33、ng the width and thickness of the test specimen to an incrementaldiscrimination of at least 0.025 mm (0.001 in.) shouldshall be used. All width and thickness measurements of rigid and semi-rigidplastics may be measured are measurable with a hand micrometer with ratchet. A suitableratchet as describe
34、d in Test MethodD5947. A similar instrument for measuring the thickness of non-rigid test specimens shall have:have a reduced contact measuringpressure of 25 6 2.5 kPa (3.6 6 0.036 psi), a movable circular contact foot 6.35 6 0,025 mm (0.250 6 0.001 in.) in diameterand a fixed anvil 6.35 6 0,025 mm
35、(0.250 6 0.001 in.) in diameter and being parallel to the contact foot within 0.005 mm (0.0002in.) over the entire foot area. Flatness 0.36 psi). Parallelism and flatness of foot and anvil shall conform to the portion of thecalibration section of Test Method D5947.7. Test Specimen7.1 The specimens m
36、ay be cutMethods to produce the specimens include cutting them from sheets, plates, or molded shapes,or may be molded molding them to the desired finished dimensions. The actual dimensions used in Section 12 (Calculation) shallbe measured in accordance with Test Method D5947.NOTE 3Any necessary poli
37、shing of specimens shall be done only in the lengthwise direction of the specimen.7.1.1 Any necessary polishing of specimens shall be done only in the lengthwise direction of the specimen.7.2 Sheet Materials (Except Laminated Thermosetting Materials and Certain Materials Used for Electrical Insulati
38、on,Including Vulcanized Fiber and Glass Bonded Mica):7.2.1 Materials 1.6 mm (116 in.) or Greater in ThicknessFor flatwise tests, the depth of the specimen shall be the thicknessof the material. For edgewise tests, the width of the specimen shall be the thickness of the sheet, and the depth shall not
39、 exceedthe width (see Notes 53 and 64). For all tests, the support span shall be 16 (tolerance 6 1) times the depth of the beam. Specimenwidth shall not exceed one fourth of the support span for specimens greater than 3.2 mm (18 in.) in depth. Specimens 3.2 mm orNOTE 1Default radii 5.0 mm; see 6.2.F
40、IG. 2 Loading Noses and Supports (Example of One Third Support Span)D6272 173less in depth shall be 12.7 mm (12 in.) in width. The specimen shall be long enough to allow for overhanging on each end of atleast 10 % of the support span, but in no case less than 6.4 mm (14 in.) on each end. Overhang sh
41、all be sufficient to prevent thespecimen from slipping through the supports.NOTE 4Whenever possible, the original surface of the sheet shall be unaltered. However, where testing machine limitations make it impossible tofollow the above criterion on the unaltered sheet, one or both surfaces shall be
42、machined to provide the desired dimensions, and the location of thespecimens with reference to the total depth shall be noted. The value obtained on specimens with machined surfaces may differ from those obtained onspecimens with original surfaces. Consequently, any specifications for flexural prope
43、rties on the thicker sheets must state whether the original surfacesare to be retained or not. When only one surface was machined, it must be stated whether the machined surface was on the tension or compression sideof the beam.7.2.1.1 Whenever possible, the original surface of the sheet shall be un
44、altered. However, where testing machine limitationsmake it impossible to follow the above criterion on the unaltered sheet, one or both surfaces shall be machined to provide thedesired dimensions, and the location of the specimens with reference to the total depth shall be noted. It is feasible that
45、 the valueobtained on specimens with machined surfaces will differ from those obtained on specimens with original surfaces. Consequently,any specifications for flexural properties on the thicker sheets must state whether the original surfaces are to be retained or not.When only one surface was machi
46、ned, it must be stated whether the machined surface was on the tension or compression side ofthe beam.NOTE 3Edgewise tests are not applicable for sheets that are so thin that specimens meeting these requirements cannot be cut. If specimen depthexceeds the width, buckling may occur.NOTE 5Edgewise tes
47、ts are not applicable for sheets that are so thin that specimens meeting these requirements cannot be cut. If specimen depthexceeds the width, buckling may occur.7.2.2 Materials Less than 1.6 m (116 in.) in ThicknessThe specimen shall be 50.8 mm (2 in.) long by 12.7 mm (12 in.) wide,tested flatwise
48、on a 25.4-mm (1-in.) support span.NOTE 4Use of the formulas for simple beams cited in these test methods for calculating results presumes that beam width is small in comparisonwith the support span. Therefore, the formulas do not apply rigorously to these dimensions.NOTE 5Where machine sensitivity i
49、s such that specimens of these dimensions cannot be measured, wider specimens or shorter support spans, or both,may be used, provided the support span-to-depth ratio is at least 14 to 1. All dimensions must be stated in the report (see also Include all dimensionsin the report.Note 6).7.3 Laminated Thermosetting Materials and Sheet and Plate Materials Used for Electrical Insulation, Including VulcanizedFiber and Glass-Bonded MicaFor paper-base and fabric-base grades over 25.4 mm (1 in.) in nominal thickness, the specimensshall be machined on both surfac
