1、Designation: D 4255/D 4255M 01 (Reapproved 2007)Standard Test Method forIn-Plane Shear Properties of Polymer Matrix CompositeMaterials by the Rail Shear Method1This standard is issued under the fixed designation D 4255/D 4255M; the number immediately following the designation indicates theyear of or
2、iginal adoption 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
3、 Defense.1. Scope1.1 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 t
4、he specimen. InProcedure B, laminates clamped on opposite edges with atensile or compressive load applied to a third pair of rails in thecenter 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
5、material forms:1.2.1 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 t
6、he fixture rails.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-
7、plane shear prop-erties of polymer matrix composites may be found in Test MethodsD 5379/D 5379M and D 5448/D 5448M, and Practice D 3518/D 3518M.1.3 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 standa
8、rd 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. Within the text theinch-pounds units are shown in brackets. The valu
9、es 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.2. Referenced Documents2.1 ASTM Standards:2D 792 Test Methods for Density and Specific Gravity (Rela-ti
10、ve Density) of 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 3518/D 3518M Test Method for In-Pl
11、ane Shear Responseof Polymer Matrix Composite Materials by Tensile Test ofa 645 LaminateD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsD 5379/D 5379M Test Method for Shear Prope
12、rties ofComposite Materials by the V-Notched Beam MethodD 5448/D 5448M Test Method for Inplane Shear Propertiesof Hoop Wound Polymer Matrix Composite CylindersE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 111 Test Method for Youngs
13、Modulus, Tangent Modulus,and Chord ModulusE 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 of the Terms Precision and Bias inASTM Test MethodsE 251 Test Methods for Performance Character
14、istics of1This 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 1, 2007. Published June 2007. Originallyapproved in 1983. Last previous edition app
15、roved in 2001 as D 4255/D 4255M 01.2For 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 ASTM website.1Copyright ASTM Internatio
16、nal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Metallic Bonded Resistance Strain GagesE 456 Terminology Relating to Quality and StatisticsE 1237 Guide for Installing Bonded Resistance StrainGagesE 1309 Guide for Identification of Fiber-ReinforcedPolymer-Matr
17、ix Composite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in DatabasesE 1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property Databases2.2 ASTM Adjunct:Adjunct No. ADJD4255, Rail Shear Fi
18、xtures MachiningDrawings33. Terminology3.1 Terminology D 3878 defines terms relating to high-modulus fibers and their composites. Terminology D 883defines terms relating to plastics. Terminology E6 definesterms relating to mechanical testing. Terminology E 456 andPractice E 177 define terms relating
19、 to statistics. In the event ofa conflict between terms, Terminology D 3878 shall haveprecedence over 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,
20、using the following ASTM standard sym-bology for fundamental dimensions, shown within square brackets: Mfor mass, L for length, T for time, u for thermodynamic temperature,and nd for nondimensional quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets,
21、 as the symbolsmay have other definitions when used without the brackets.3.2 Definitions of Terms Specific 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
22、thanthrough the thickness.3.2.2 offset shear stress M/(LT2), nthe shear stressassociated with an offset of the shear chord modulus ofelasticity line along the strain axis (see 12.4).3.2.3 shear strength M/(LT2), nthe shear stress carriedby a material at failure under a pure shear condition.3.2.4 tra
23、nsition region, na strain region of a stress-strainor strain-strain curve over which a significant change 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 long
24、itudinal stress versus longitudinal strain ortransverse strain versus longitudinal strain. In certain cases, thenonlinear response may be conveniently approximated by abilinear fit. There are several physical reasons for the existenceof a transition region. Common examples include matrixcracking und
25、er tensile loading and ply delamination.3.2.5 traveler, na small piece of the same material as, andprocessed 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 ar
26、ea of test specimenBy= percent bending of specimenCV = coefficient of variation statistic of a sample populationfor a given property, %F12o= offset shear stress, the value of the shear stress at theintersection of the stress-strain plot with a line passing throughthe offset strain value at zero stre
27、ss and with a slope equal tothe shear chord modulus of elasticityFu= ultimate shear stressG = shear modulus of elasticityh = specimen thicknessl = specimen length, the dimension parallel to the rails in thegage sectionn = number of specimensPi= load carried by test specimen at ith data pointPmax= lo
28、ad carried by a test specimen that is the lesser of (1)the maximum load before failure, (2) the load at 5 % shearstrain, or (3) the load at the bending limit (see 11.8.1)sn1= sample standard deviationxi= measured or derived property for an individual specimenfrom the sample populationx= sample mean
29、(average)g = shear straine = indicated normal strain from strain transducere =10-6m/m (10-6in./in.)ti= shear stress at ith data point4. Summary 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 para
30、llel steel loading rails, see Figs.1 and 2. When loaded in tension, this fixture introduces shearforces in the specimen that produce failures across the panel.This test method is typical but not the only configurationusable. The two-rail shear fixtures can also be compressionloaded. The load may be
31、applied to failure.4.1.1 If load-strain data are required, the specimen may beinstrumented with strain gages. Two three-element strain gagerosettes are installed at corresponding locations on both facesof the specimen.4.2 Procedure B: Three-Rail Shear TestA flat panel,clamped securely between pairs
32、of rails on opposite edges andin its center, is loaded by supporting the side rails while loadingthe center rails. See Figs. 3-5.Aload on the center rail of eithertension or compression produces a shear load in each section ofthe specimen. The load may be applied to failure.4.2.1 The test fixture co
33、nsists of three pairs of 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 co
34、mpression. It is also permissible to load the middle rails intension, but this requires attaching the base fixture to the testmachine.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. A
35、DJD4255.D 4255/D 4255M 01 (2007)24.2.2 If load-strain data are required, the specimen may beinstrumented with strain gages. Three-element strain gagerosettes are to be installed at corresponding locations onopposite faces of the specimen.4.3 Detailed fixture drawings are available as ASTM Ad-junct N
36、o. ADJD4255.5. Significance and Use5.1 These shear tests are designed to produce in-plane shearproperty data for material specifications, research and devel-opment, and design. Factors that influence the shear responseand should therefore be reported include: material, methods ofmaterial preparation
37、 and lay-up, specimen stacking sequence,specimen preparation, specimen conditioning, environment oftesting, specimen alignment and gripping, speed of testing,time at temperature, void content, and fiber volume reinforce-ment content. Properties that may be measured by this testmethod include:5.1.1 I
38、n-plane shear stress versus shear strain response,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 thestrain at failure is greater than 5 %, the shear stress correspond-ing to 5 % shear strain should be reported.6.
39、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 close for a specific material for a given engineeringpurpose. The off-axis load of the two-rail meth
40、od introduces acomparatively small tensile load in the panel.6.2 Material and Specimen PreparationPoor materialfabrication practices, lack of control of fiber alignment, anddamage induced by improper specimen machining are knowncauses of high material data scatter in composites.6.3 Determination of
41、FailureRail shear specimens, espe-cially thin ones, can buckle during load application. Bucklingcan be detected by measuring surface strains on opposite facesof the specimens with three-element strain gage rosettes. Datameasured with the specimen in a buckled state are notrepresentative of the mater
42、ial shear properties. Modulus datamust be checked to confirm that buckling has not occurred inthe modulus measurement range. Strength measurements mustbe checked to confirm that shear strength has not beeninfluenced by specimen buckling. Failure by buckling shouldnot be interpreted as indicating the
43、 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 ascontrasted to the overall buckling failure previously described.Differences in strain gage readings
44、 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 methods are discussed in7.2.3.6.5 End EffectsThis test method assumes a state of pureshear throughout
45、 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
46、 induced in the material shear data.7. Apparatus7.1 MicrometersThe micrometer(s) shall use a suitablesize diameter ball interface on irregular surfaces such as thebag-side of a laminate and a flat anvil interface on machinededges or very-smooth tooled surfaces. The accuracy of theinstruments shall b
47、e suitable for reading to within 1 % of thesample length and thickness. For typical specimen geometries,an instrument with an accuracy of 62.5 m 60.0001 in. isdesirable for thickness measurement, while an instrument withan accuracy of 625 m 60.001 in. is desirable for lengthmeasurement.7.2 Rail Shea
48、r Fixtures7.2.1 Two-Rail ShearA two-rail shear fixture is shown inFigs. 1 and 2. Detailed fixture drawings are available as ASTMAdjunct No. ADJD4255. The test fixture consists of two pairsof rails which can clamp the test specimen with through bolts.The rails are then attached to the test machine th
49、rough pins, aload plate that also aligns the rails with each other, and a clevis4A. K. Hussain and D. F. Adams, “The Wyoming-Modified Two-Rail Shear TestFixture for Composite Materials,” Journal of Composites Technology and Research,Vol 21, No. 4, October 1999, pp. 215-223.FIG. 1 Procedure A Assembly Rail Shear ApparatusD 4255/D 4255M 01 (2007)3that connects directly to the test machine. This equipment istypical but not the only configuration usable. The two-railshear fixture can be compression loaded. Also see 7.2.3 for railmodifications
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