1、Designation: D 2344/D 2344M 00 (Reapproved 2006)Standard Test Method forShort-Beam Strength of Polymer Matrix Composite Materialsand Their Laminates1This standard is issued under the fixed designation D 2344/D 2344M; the number immediately following the designation indicates theyear of original adop
2、tion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.
3、 Scope1.1 This test method determines the short-beam strength ofhigh-modulus fiber-reinforced composite materials. The speci-men is a short beam machined from a curved or a flat laminateup to 6.00 mm 0.25 in. thick. The beam is loaded inthree-point bending.1.2 Application of this test method is limi
4、ted to continuous-or discontinuous-fiber-reinforced polymer matrix composites,for which the elastic properties are balanced and symmetricwith respect to the longitudinal axis of the beam.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is t
5、heresponsibility 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.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach
6、system may not be exact equivalents; therefore, eachsystem must be used independently of the other. Combiningvalues from the two systems may result in nonconformancewith the standard.2. Referenced Documents2.1 ASTM Standards:2D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of
7、 Plastics by DisplacementD 883 Terminology Relating to PlasticsD 2584 Test Method for Ignition Loss of Cured ReinforcedResinsD 2734 Test Methods for Void Content of Reinforced Plas-ticsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3878 Terminology for Composite MaterialsD 5229/D
8、 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsD 5687/D 5687M Guide for Preparation of Flat CompositePanels with Processing Guidelines for Specimen Prepara-tionE4 Practices for Force Verification of Testing MachinesE6 Terminolo
9、gy Relating to Methods of Mechanical Test-ingE18 Test Methods for Rockwell Hardness and RockwellSuperficial Hardness of Metallic MaterialsE 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, the Average for aCharacteristic of a Lot or ProcessE 177 Practice for Use
10、 of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to Quality and StatisticsE 1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databas
11、esE 1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property Databases3. Terminology3.1 DefinitionsTerminology D 3878 defines the terms re-lating to high-modulus fibers and their composites. Terminol-ogy D 883 defines terms relating to plastics. Terminolo
12、gy E6defines terms relating to mechanical testing. TerminologyE 456 and Practice E 177 define terms relating to statistics. Inthe event of a conflict between definitions, TerminologyD 3878 shall have precedence over the other documents.NOTE 1If the term represents a physical quantity, its analytical
13、dimensions are stated immediately following the term (or letter symbol) infundamental dimension form, using the following ASTM standard sym-bology for fundamental dimensions, shown within square brackets: Mfor mass, L for length, T for time, Q for thermodynamic temperature,and nd for nondimensional
14、quantities. Use of these symbols is restricted1This test method is under the jurisdiction of ASTM Committee D-30 onComposite Materials and is the direct responsibility of Subcommittee D30.04 onLamina and Laminate Test Methods.Current edition approved Jan. 15, 2006. Published January 2006. Originally
15、approved in 1965. Last previous edition approved in 2000 as D 2344 00e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe AS
16、TM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to analytical dimensions when used with square brackets, as the symbolsmay have other definitions when used without the brackets.3.2 Definitions of Terms Specific to This Sta
17、ndard:3.2.1 balanced laminate, na continuous fiber-reinforcedlaminate in which each +u lamina, measured with respect to thelaminate reference axis, is balanced by a u lamina of the samematerial (for example, 0/+45/45/+45/45/0).3.2.2 short-beam strength, nthe shear stress as calculatedin Eq 1, develo
18、ped at the specimen mid-plane at the failureevent specified in 11.6.3.2.2.1 DiscussionAlthough shear is the dominant appliedloading in this test method, the internal stresses are complexand a variety of failure modes can occur. Elasticity solutions byBergetal(1)3, Whitney (2), and Sullivan and Van O
19、ene (3)have all demonstrated inadequacies in classical beam theory indefining the stress state in the short-beam configuration. Thesesolutions show that the parabolic shear-stress distribution aspredicted by Eq 1 only occurs, and then not exactly, on planesmidway between the loading nose and support
20、 points. Awayfrom these planes, the stress distributions become skewed, withpeak stresses occurring near the loading nose and supportpoints. Of particular significance is the stress state local to theloading nose in which the severe shear-stress concentrationcombined with transverse and in-plane com
21、pressive stresseshas been shown to initiate failure. However, for the moreductile matrices, plastic yielding may alleviate the situationunder the loading nose (1) and allow other failure modes tooccur such as bottom surface fiber tension (2). Consequently,unless mid-plane interlaminar failure has be
22、en clearly ob-served, the short-beam strength determined from this testmethod cannot be attributed to a shear property, and the use ofEq 1 will not yield an accurate value for shear strength.3.2.3 symmetric laminate, na continuous fiber-reinforcedlaminate in which each ply above the mid-plane is ide
23、nticallymatched (in terms of position, orientation, and mechanicalproperties) with one below the mid-plane.3.3 Symbols:bspecimen width.CVsample coefficient of variation (in percent).Fsbsshort-beam strength.hspecimen thickness.nnumber of specimens.Pmmaximum load observed during the test.ximeasured or
24、 derived property for an individual specimenfrom the sample population.xsample mean (average).4. Summary of Test Method4.1 The short-beam test specimens (Figs. 1-4) are center-loaded as shown in Figs. 5 and 6. The specimen ends rest ontwo supports that allow lateral motion, the load being appliedby
25、means of a loading nose directly centered on the midpointof the test specimen.5. Significance and Use5.1 In most cases, because of the complexity of internalstresses and the variety of failure modes that can occur in thisspecimen, it is not generally possible to relate the short-beamstrength to any
26、one material property. However, failures arenormally dominated by resin and interlaminar properties, andthe test results have been found to be repeatable for a givenspecimen geometry, material system, and stacking sequence(4).5.2 Short-beam strength determined by this test method canbe used for qual
27、ity control and process specification purposes.It can also be used for comparative testing of compositematerials, provided that failures occur consistently in the samemode (5).5.3 This test method is not limited to specimens within therange specified in Section 8, but is limited to the use of aloadi
28、ng span length-to-specimen thickness ratio of 4.0 and aminimum specimen thickness of 2.0 mm 0.08 in.6. Interferences6.1 Accurate reporting of observed failure modes is essen-tial for meaningful data interpretation, in particular, the detec-tion of initial damage modes.7. Apparatus7.1 Testing Machine
29、, properly calibrated, which can beoperated at a constant rate of crosshead motion, and which the3Boldface numbers in parentheses refer to the list of references at the end of thisstandard.NOTE 1Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASM B46.1-1986.NOTE 2Ply orientation tolerance 60.5 r
30、elative to B.FIG. 1 Flat Specimen Configuration (SI)D 2344/D 2344M 00 (2006)2error in the loading system shall not exceed 61 %. Theload-indicating mechanism shall be essentially free of inertialag at the crosshead rate used. Inertia lag may not exceed 1 %of the measured load. The accuracy of the tes
31、ting machine shallbe verified in accordance with Practices E4.7.2 Loading Nose and Supports, as shown in Figs. 5 and 6,shall be 6.00-mm (0.250-in.) and 3.00-mm (0.125-in.) diametercylinders, respectively, with a hardness of 60 to 62 HRC, asspecified in Test Methods E18, and shall have finely grounds
32、urfaces free of indentation and burrs with all sharp edgesrelieved.7.3 MicrometersFor width and thickness measurements,the micrometers shall use a 4- to 5-mm (0.16- to 0.2-in.)nominal diameter ball interface on an irregular surface such asthe bag side of a laminate and a flat anvil interface on mach
33、inededges or very smooth tooled surfaces. A micrometer or caliperwith flat anvil faces shall be used to measure the length of thespecimen. The accuracy of the instrument(s) shall be suitablefor reading to within 1 % of the sample dimensions. For typicalsection geometries, an instrument with an accur
34、acy of 60.002mm (60.0001 in.) is desirable for thickness and width mea-surement, while an instrument with an accuracy of 60.1 mm(60.004 in.) is adequate for length measurement.7.4 Conditioning Chamber, when conditioning materials atnonlaboratory environments, a temperature/vapor-level-controlled env
35、ironmental conditioning chamber is required thatshall be capable of maintaining the required temperature towithin 63C (65F) and the required vapor level to within63 %. Chamber conditions shall be monitored either on anautomated continuous basis or on a manual basis at regularintervals.7.5 Environmen
36、tal Test Chamber, an environmental testchamber is required for test environments other than ambienttesting laboratory conditions. This chamber shall be capable ofmaintaining the test specimen at the required test environmentduring the mechanical test method.8. Sampling and Test Specimens8.1 Sampling
37、Test at least five specimens per test condi-tion unless valid results can be gained through the use of fewerspecimens, as in the case of a designed experiment. Forstatistically significant data, consult the procedures outlined inPractice E 122. Report the method of sampling.8.2 Geometry:8.2.1 Lamina
38、te ConfigurationsBoth multidirectional andpure unidirectional laminates can be tested, provided that thereare at least 10 % 0 fibers in the span direction of the beam(preferably well distributed through the thickness), and that thelaminates are both balanced and symmetric with respect to thespan dir
39、ection of the beam.8.2.2 Specimen ConfigurationsTypical configurations forthe flat and curved specimens are shown in Figs. 1-4. Forspecimen thicknesses other than those shown, the followinggeometries are recommended:Specimen length = thickness 3 6Specimen width, b = thickness 3 2.0NOTE 2Analysis rep
40、orted by Lewis and Adams (6) has shown that awidth-to-thickness ratio of greater than 2.0 can result in a significantwidth-wise shear-stress variation.8.2.2.1 For curved beam specimens, it is recommended thatthe arc should not exceed 30. Also, for these specimens, thespecimen length is defined as th
41、e minimum chord length.8.3 Specimen PreparationGuide D 5687/D 5687M pro-vides recommended specimen preparation practices and shouldbe followed where practical.8.3.1 Laminate FabricationLaminates may be hand-laid,filament-wound or tow-placed, and molded by any suitablelaminating means, such as press,
42、 bag, autoclave, or resintransfer molding.8.3.2 Machining MethodsSpecimen preparation is impor-tant for these specimens. Take precautions when cuttingspecimens from the rings or plates to avoid notches, undercuts,rough or uneven surfaces, or delaminations as a result ofinappropriate machining method
43、s. Obtain final dimensions bywater-lubricated precision sawing, milling, or grinding. Theuse of diamond tooling has been found to be extremelyeffective for many material systems. Edges should be flat andparallel within the specified tolerances.8.3.3 LabelingLabel the specimens so that they will bedi
44、stinct from each other and traceable back to the raw material,in a manner that will both be unaffected by the test method andnot influence the test method.NOTE 1Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASME B46.1-1986.NOTE 2Ply orientation tolerance 60.5 relative to B.FIG. 2 Flat Specimen
45、 Configuration (Inch Pound)D 2344/D 2344M 00 (2006)39. Calibration9.1 The accuracy of all measuring equipment shall havecertified calibrations that are current at the time of use of theequipment.10. Conditioning10.1 Standard Conditioning ProcedureUnless a differentenvironment is specified as part of
46、 the test method, conditionthe test specimens in accordance with Procedure C of TestMethod D 5229/D 5229M, and store and test at standardlaboratory atmosphere (23 6 3C (73 6 5F) and 50 6 10 %relative humidity).11. Procedure11.1 Parameters to Be Specified Before Test:11.1.1 The specimen sampling meth
47、od and coupon geom-etry.11.1.2 The material properties and data-reporting formatdesired.NOTE 3Determine specific material property, accuracy, and data-reporting requirements before test for proper selection of instrumentationand data-recording equipment. Estimate operating stress levels to aid incal
48、ibration of equipment and determination of equipment settings.11.1.3 The environmental conditioning test parameters.11.1.4 If performed, the sampling test method, coupongeometry, and test parameters used to determine density andreinforcement volume.11.2 General Instructions:NOTE 1Drawing interpretat
49、ion per ANSI Y14.5-1982 and ANSI/ASM B46.1-1986.NOTE 2Ply orientation tolerance 60.5 relative to A.FIG. 3 Curved Specimen Configuration (SI)D 2344/D 2344M 00 (2006)411.2.1 Report any deviations from this test method, whetherintentional or inadvertent.11.2.2 If specific gravity, density, reinforcement volume, orvoid volume are to be reported, then obtain these samples fromthe same panels as the test samples. Specific gravity anddensity may be evaluated by means of Test Methods D 792.Volume percent of the constituen
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