1、Designation: D4255/D4255M 15AStandard Test Method forIn-Plane Shear Properties of Polymer Matrix CompositeMaterials by the Rail Shear Method1This standard is issued under the fixed designation D4255/D4255M; the number immediately following the designation indicates theyear of original adoption or, i
2、n the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope
3、1.1 This test method determines the in-plane shear proper-ties of high-modulus fiber-reinforced composite materials byeither of two procedures. In Procedure A, laminates clampedbetween two pairs of loading rails are tested. When loaded intension the rails introduce shear forces in the specimen. InPr
4、ocedure B, laminates clamped on opposite edges with atensile or compressive force applied to a third pair of rails inthe center are tested.1.2 Application of this test method is limited to continuous-fiber or discontinuous-fiber-reinforced polymer matrix com-posites in the following material forms:1
5、.2.1 Laminates composed only of unidirectional fibrouslaminae, with the fiber direction oriented either parallel orperpendicular to the fixture rails.1.2.2 Laminates composed only of woven fabric filamentarylaminae with the warp direction oriented either parallel orperpendicular to the fixture rails
6、.1.2.3 Laminates of balanced and symmetric construction,with the 0 direction oriented either parallel or perpendicular tothe fixture rails.1.2.4 Short-fiber-reinforced composites with a majority ofthe fibers being randomly distributed.NOTE 1Additional test methods for determining in-plane shearprope
7、rties of polymer matrix composites may be found in Test MethodsD3518/D3518M, D5379/D5379M, D5448/D5448M, and D7078/D7078M.1.3 The reproducibility of this test method can be affectedby the presence of shear stress gradients in the gage section andstress concentrations at the gripping areas. Test Meth
8、odsD5379/D5379M and D7078/D7078M provide superior shearresponse in comparison to this test method, as their specimenconfigurations produce a relatively pure and uniform shearstress state in the gage section.1.4 The technical content of this standard has been stablesince 2001 without significant obje
9、ction from its stakeholders.As there is limited technical support for the maintenance of thisstandard, changes since that date have been limited to itemsrequired to retain consistency with other ASTM D30 Commit-tee standards, including editorial changes and incorporation ofupdated guidance on microm
10、eters and calipers, strain gagerequirements, speed of testing, specimen preconditioning andenvironmental testing. Future maintenance of the standard willonly be in response to specific requests and performed only astechnical support allows.1.5 The values stated in either SI units or inch-pound units
11、are to be regarded separately as standard. The values stated ineach system are not exact equivalents; therefore, each systemmust be used independently of the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.1.5.1 Within the text the inch-pounds units are show
12、n inbrackets.1.6 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.2.
13、 Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD2584 Test Method for Ignition Loss of Cured ReinforcedResinsD2734 Test Methods for Void Content of Reinforced PlasticsD3171
14、 Test Methods for Constituent Content of CompositeMaterials1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.04 onLamina and Laminate Test Methods.Current edition approved May 15, 2015. Published May 2015. Ori
15、ginallyapproved in 1983. Last previous edition approved in 2015 as D4255/D4255M 15.DOI: 10.1520/D4255_D4255M-15A.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
16、 standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3518/D3518M Test Method for In-Plane Shear Responseof Polymer Matrix Composite Materials by Tensile Test ofa 645 LaminateD3878 Termin
17、ology for Composite MaterialsD5229/D5229M Test Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsD5379/D5379M Test Method for Shear Properties of Com-posite Materials by the V-Notched Beam MethodD5448/D5448M Test Method for Inplane Shear Prope
18、rtiesof Hoop Wound Polymer Matrix Composite CylindersD7078/D7078M Test Method for Shear Properties of Com-posite Materials by V-Notched Rail Shear MethodE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE111 Test Method for Youngs Modulus,
19、 Tangent Modulus,and Chord ModulusE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE251 Test Methods for Performance Characteristics of Me-tallic
20、 Bonded Resistance Strain GagesE456 Terminology Relating to Quality and StatisticsE1237 Guide for Installing Bonded Resistance Strain GagesE1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforc
21、ed Composite Materials in DatabasesE1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property Databases2.2 ASTM Adjunct:Adjunct No. ADJD4255, Rail Shear Fixtures MachiningDrawings33. Terminology3.1 Terminology D3878 defines terms relating to high-modulus f
22、ibers and their composites. Terminology D883 de-fines terms relating to plastics. Terminology E6 defines termsrelating to mechanical testing. Terminology E456 and PracticeE177 define terms relating to statistics. In the event of aconflict between terms, Terminology D3878 shall have prece-dence over
23、the other terminology standards.NOTE 2If the term represents a physical quantity, its analyticaldimensions 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:
24、 Mfor mass, L for length, T for time, for thermodynamic temperature,and nd for nondimensional quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets, as the symbolsmay have other definitions when used without the brackets.3.2 Definitions of Terms Specif
25、ic to This Standard:3.2.1 in-plane shear, nshear associated with shear forcesapplied to the edges of the laminate so that the resulting sheardeformations occur in the plane of the laminate rather thanthrough the thickness.3.2.2 offset shear stress M/(LT2),nthe shear stressassociated with an offset o
26、f the shear chord modulus ofelasticity line along the strain axis (see 13.5).3.2.3 shear strength M/(LT2),nthe shear stress carriedby a material at failure under a pure shear condition.3.2.4 transition region, na strain region of a stress-strainor strain-strain curve over which a significant change
27、in theslope of the curve occurs within a small strain range.3.2.4.1 DiscussionMany filamentary composite materialsexhibit a nonlinear response during loading, such as seen inplots of either longitudinal stress versus longitudinal strain ortransverse strain versus longitudinal strain. In certain case
28、s, thenonlinear response may be conveniently approximated by abilinear fit. There are several physical reasons for the existenceof a transition region. Common examples include matrixcracking under tensile loading and ply delamination.3.2.5 traveler, na small piece of the same material as, andprocess
29、ed similarly to, the test specimen, used for example tomeasure moisture content as a result of conditioning. This isalso sometimes termed as a reference sample.3.3 Symbols:A = cross-sectional area of test specimenBy= percent bending of specimenCV = coefficient of variation statistic of a sample popu
30、lationfor a given property, %3A copy of the detailed drawing for the construction of the fixtures shown inFigs. 1 and 2 is available at a nominal cost from ASTM Headquarters. RequestAdjunct No. ADJD4255.FIG. 1 Procedure A Assembly Rail Shear ApparatusD4255/D4255M 15A2F12o= offset shear stress, the v
31、alue of the shear stress at theintersection of the stress-strain plot with a line passing throughthe offset strain value at zero stress and with a slope equal tothe shear chord modulus of elasticityFu= ultimate shear stressG = shear modulus of elasticityh = specimen thicknessl = specimen length, the
32、 dimension parallel to the rails in thegage sectionn = number of specimensPi= force carried by test specimen at ith data pointPmax= force carried by a test specimen that is the lesser of(1) the maximum force before failure, (2) the force at 5 %engineering shear strain, or (3) the force at the bendin
33、g limit(see 11.8.1)Sn1= sample standard deviationxi= measured or derived property for an individual specimenfrom the sample population = sample mean (average) = engineering shear strain = indicated normal strain from strain transducer =10-6m/m (10-6in./in.)i= shear stress at ith data point4. Summary
34、 of Test Method4.1 Procedure A: Two-Rail Shear TestA flat panel withholes along opposing edges is clamped, usually by throughbolts, between two pairs of parallel steel loading rails, see Figs.1 and 2. When loaded in tension, this fixture introduces shearforces in the specimen that produce failures a
35、cross the panel.This test method is typical but not the only configurationusable. The two-rail shear fixtures can also be compressionloaded. The force may be applied to failure.4.1.1 If force-strain data are required, the specimen may beinstrumented with strain gages. Biaxial strain gage rosettes ar
36、einstalled at corresponding locations on each face of thespecimen.4.2 Procedure B: Three-Rail Shear TestA flat panel,clamped securely between pairs of rails on opposite edges andin its center, is loaded by supporting the side rails while loadingthe center rails. See Figs. 3-5. A force on the center
37、rail ofeither tension or compression produces a shear force in eachsection of the specimen. The force may be applied to failure.FIG. 2 Procedure A Partially Assembled Typical Test FixtureFIG. 3 Procedure B Assembly Rail Shear FixtureD4255/D4255M 15A34.2.1 The test fixture consists of three pairs of
38、parallel railsusually bolted to the test specimen by through bolts. The twooutside pairs of rails are attached to a base plate which rests onthe test machine. A third pair (middle rails) is guided througha slot in the top of the base fixture. The unit is normally loadedin compression. It is also per
39、missible to load the middle rails intension, but this requires attaching the base fixture to the testmachine.4.2.2 If force-strain data are required, the specimen may beinstrumented with strain gages. Biaxial strain gages are to beinstalled at corresponding locations on opposite faces of thespecimen
40、.4.3 Detailed fixture drawings are available as ASTM Ad-junct No. ADJD4255.5. Significance and Use5.1 These shear tests are designed to produce in-plane shearproperty data for material specifications, research anddevelopment, and design. Factors that influence the shearresponse and should therefore
41、be reported include: material,methods of material preparation and lay-up, specimen stackingsequence, specimen preparation, specimen conditioning, envi-ronment of testing, specimen alignment and gripping, speed oftesting, time at temperature, void content, and fiber volumereinforcement content. Prope
42、rties that may be measured by thistest method include:5.1.1 In-plane shear stress versus engineering shear strainresponse,5.1.2 In-plane shear chord modulus of elasticity,5.1.3 Offset shear stress, and5.1.4 Maximum in-plane shear stress. In cases in which theengineering shear strain at failure is gr
43、eater than 5 %, the shearstress corresponding to 5 % engineering shear strain should bereported.6. Interferences6.1 There are no standard test methods capable of producinga perfectly pure and uniform shear stress condition to failurefor every material, although some test methods can comeacceptably c
44、lose for a specific material for a given engineeringpurpose. The off-axis force of the two-rail method introduces acomparatively small tensile force in the panel.6.2 Material and Specimen PreparationPoor material fab-rication practices, lack of control of fiber alignment, anddamage induced by improp
45、er specimen machining are knowncauses of high material data scatter in composites.6.3 Determination of FailureRail shear specimens, espe-cially thin ones, can buckle during force application. Bucklingcan be detected by measuring surface strains on opposite facesof the specimens with biaxial strain g
46、ages . Data measured withthe specimen in a buckled state are not representative of thematerial shear properties. Modulus data must be checked toconfirm that buckling has not occurred in the modulus mea-surement range. Strength measurements must be checked toconfirm that shear strength has not been i
47、nfluenced by speci-men buckling. Failure by buckling should not be interpreted asindicating the maximum shear strength.6.3.1 Ply delamination is another possible failure mode forlaminates containing a large number of 45 plies. This failurereflects instability of 45 plies loaded in compression ascont
48、rasted to the overall buckling failure previously described.Differences in strain gage readings will not be noticeable, butthe failure can be identified by delaminated plies in contrast tofiber breakage.46.4 GrippingFailure through bolt holes indicates inad-equate gripping. Alternate gripping method
49、s are discussed in7.2.3.6.5 End EffectsThis test method assumes a state of pureshear throughout the length of the specimen gage section.However, the gage section ends have zero shear stress becauseno traction and no constraints are applied there. A stresstransition region exists between the ends and interior portionsof the gage section. The length of this transition regiondetermines the error induced in the material shear data.4A. K. Hussain and D. F. Adams, “The Wyoming-Modified Two-Rail Shear TestFixture for Composite Materials,” Journa
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