1、Designation: D6856/D6856M 03 (Reapproved 2016)Standard Guide forTesting Fabric-Reinforced “Textile” Composite Materials1This standard is issued under the fixed designation D6856/D6856M; the number immediately following the designation indicates theyear of original adoption or, in the case of revisio
2、n, 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.INTRODUCTIONA variety of fabric-reinforced composite materials have been developed for use in aerospace,automotive,
3、 and other applications. These composite materials are reinforced with continuous fiberyarns that are formed into two-dimensional or three-dimensional fabrics. Various fabric constructions,such as woven, braided, stitched, and so forth, can be used to form the fabric reinforcement. Due tothe nature
4、of the reinforcement, these materials are often referred to as “textile” composites.Textile composites can be fabricated from 2-dimensional (2-D) or 3-dimensional (3-D) fabrics.Stitched preforms and 3-D fabrics contain through-thickness yarns, which can lead to greaterdelamination resistance. Textil
5、e composites are also amenable to automated fabrication. However, themicrostructure (or fiber architecture) of a textile composite, which consists of interlacing yarns, canlead to increased inhomogeneity of the local displacement fields in the laminate. Depending upon thesize of the yarns and the pa
6、ttern of the weave or braid, the inhomogeneity within a textile compositecan be large compared to traditional tape laminates.Thus, special care should be exercised in the use of the currentASTM standards developed for highperformance composites. In many cases, the current ASTM standards are quite ad
7、equate if properattention is given to the special testing considerations for textile composites covered in this guide.However, in some cases, current standards do not meet the needs for testing of the required properties.This guide is intended to increase the users awareness of the special considera
8、tions necessary for thetesting of these materials. It also provides the user with recommended ASTM standards that areapplicable for evaluating textile composites. The specific properties for which current ASTMstandards might not apply are also highlighted in this guide.1. Scope1.1 This guide is appl
9、icable to the testing of textile com-posites fabricated using fabric preforms, such as weaves,braids, stitched preforms, and so forth, as the reinforcement.The purpose of this guide is to:1.1.1 Ensure that proper consideration is given to the uniquecharacteristics of these materials in testing.1.1.2
10、 Assist the user in selecting the best currently availableASTM test method for the measurement of commonly evalu-ated material properties for this class of materials.1.2 Areas where current ASTM test methods do not meetthe needs for testing of textile composites are indicated.1.3 It is not the inten
11、t of this guide to cover all test methodswhich could possibly be used for textile composites. Only themost commonly used and most applicable standards areincluded.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system ma
12、y not be exact equivalents; therefore, each1This guide is under the jurisdiction of ASTM Committee D30 on CompositeMaterials and is the direct responsibility of Subcommittee D30.04 on Lamina andLaminate Test Methods.Current edition approved Sept. 1, 2016. Published September 2016. Originallyapproved
13、 in 2003. Last previous edition approved in 2003 as D6856-03(2008)1.DOI: 10.1520/D6856_D6856M-03R16.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1system shall be used independently of the other. Combiningvalues from the two systems
14、may result in non-conformancewith the standard.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 regu
15、latory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2D790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Term
16、inology Relating to PlasticsD2344/D2344M Test Method for Short-Beam Strength ofPolymer Matrix Composite Materials andTheir LaminatesD3039/D3039M Test Method for Tensile Properties of Poly-mer Matrix Composite MaterialsD3171 Test Methods for Constituent Content of CompositeMaterialsD3410/D3410M Test
17、Method for Compressive Properties ofPolymer Matrix Composite Materials with UnsupportedGage Section by Shear LoadingD3479/D3479M Test Method for Tension-Tension Fatigueof Polymer Matrix Composite MaterialsD3518/D3518M Test Method for In-Plane Shear Responseof Polymer Matrix Composite Materials by Te
18、nsile Test ofa 645 LaminateD3846 Test Method for In-Plane Shear Strength of Rein-forced PlasticsD3878 Terminology for Composite MaterialsD4255/D4255M Test Method for In-Plane Shear Propertiesof Polymer Matrix Composite Materials by the Rail ShearMethodD5229/D5229M Test Method for MoistureAbsorption
19、Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsD5379/D5379M Test Method for Shear Properties of Com-posite Materials by the V-Notched Beam MethodD5528 Test Method for Mode I Interlaminar FractureTough-ness of Unidirectional Fiber-Reinforced Polymer MatrixCompositesD5766
20、/D5766M Test Method for Open-Hole TensileStrength of Polymer Matrix Composite LaminatesD5961/D5961M Test Method for Bearing Response of Poly-mer Matrix Composite LaminatesD6115 Test Method for Mode I Fatigue DelaminationGrowth Onset of Unidirectional Fiber-Reinforced Poly-mer Matrix CompositesD6415
21、Test Method for Measuring the Curved BeamStrength of a Fiber-Reinforced Polymer-Matrix Compos-iteD6272 Test Method for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-als by Four-Point BendingD6484/D6484M Test Method for Open-Hole CompressiveStrength of Po
22、lymer Matrix Composite LaminatesD6641/D6641M Test Method for Compressive Properties ofPolymer Matrix Composite Materials Using a CombinedLoading Compression (CLC) Test FixtureD6671/D6671M Test Method for Mixed Mode I-Mode IIInterlaminar Fracture Toughness of Unidirectional FiberReinforced Polymer Ma
23、trix CompositesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE251 Test Methods for Performance Characteristics of Me-tallic Bonded Resistance Strain GagesE456
24、Terminology Relating to Quality and StatisticsE1237 Guide for Installing Bonded Resistance Strain Gages3. Terminology3.1 DefinitionsDefinitions used in this guide are definedby various ASTM methods. Terminology D3878 defines termsrelating to high-modulus fibers and their composites. Termi-nology D88
25、3 defines terms relating to plastics. Terminology E6defines terms relating to mechanical testing. Terminology E456defines terms relating to statistics. In the event of a conflictbetween definitions of terms, Terminology D3878 shall haveprecedence over the other standards.Terms relating specificallyt
26、o textile composites are defined by Ref (1).33.2 textile unit cellIn theory, textile composites have arepeating geometrical pattern based on manufacturing param-eters. This repeating pattern is often referred to as the materials“unit cell.” It is defined as the smallest section of architecturerequir
27、ed to repeat the textile pattern (see Figs. 1-4). Handlingand processing can distort the “theoretical” unit cell. Param-eters such as yarn size, yarn spacing, fabric construction, andfiber angle may be used to calculate theoretical unit celldimensions. However, several different “unit cells” may bed
28、efined for a given textile architecture. For example, Fig. 2shows two different unit cells for the braided architectures.Thus, unit cell definition can be somewhat subjective based onvarying interpretations of the textile architecture. The user isreferred to Refs (1, 2) for further guidance. In this
29、 guide, to beconsistent, the term “unit cell” is used to refer to the smallestunit cell for a given textile architecture. This smallest unit cellis defined as the smallest section of the textile architecturerequired to replicate the textile pattern by using only in-planetranslations (and no rotation
30、s) of the unit cell. Examples of thesmallest unit cells for some of the commonly used textilecomposites are shown in Figs. 1-4. For the 3-D weaves in Figs.3 and 4, the smallest unit cell length (as indicated) is defined bythe undulating pattern of the warp yarns. The smallest unit cell2For reference
31、d 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.3The boldface numbers in parentheses refer to the list of references at the
32、 end ofthis standard.D6856/D6856M 03 (2016)2width is the distance between two adjacent warp stuffer yarncolumns (in the fill yarn direction) and the smallest unit cellheight is the consolidated woven composite thickness.FIG. 1 Smallest Unit Cells for Plain Weave and 5-Harness Satin Weave Architectur
33、esFIG. 2 Smallest Unit Cells for a 2-D Braid and a 22, 2-D Triaxial BraidFIG. 3 Smallest Unit Cell Length for Through-Thickness Angle-Interlock WeaveD6856/D6856M 03 (2016)34. Significance and Use4.1 This guide is intended to serve as a reference for thetesting of textile composite materials.4.2 The
34、use of this guide ensures that proper considerationis given to the unique characteristics of these materials intesting. In addition, this guide also assists the user in selectingthe best currently available ASTM test method for measure-ment of commonly evaluated material properties.5. Summary of Gui
35、de5.1 Special testing considerations unique to textile compos-ites are identified and discussed. Recommendations for han-dling these considerations are provided. Special considerationscovered are included in Section 7 on Material Definition;Section 8 on Gage Selection; Section 9 on Sampling and Test
36、Specimens; Section 10 on Test Specimen Conditioning; Sec-tion 11 on Report of Results; and Section 12 on RecommendedTest Methods.5.2 Recommended ASTM test methods applicable to textilecomposites and any special considerations are provided inSection 12 for mechanical and physical properties. Section
37、13identifies areas where revised or new standards are needed fortextile composites.6. Procedure for Use6.1 Review Sections 712to become familiar with thespecial testing considerations for textile composites.6.2 Follow the recommended ASTM test method identifiedin Section 12 for determining a require
38、d property but refer backto this guide for recommendations on test specimen geometry,strain measurement, and reporting of results.7. Material Definition7.1 Constituent DefinitionVariations in type and amountof sizing on the fibers can significantly influence fabric qualityand subsequently material p
39、roperty test results. Eachconstituent, that is, the fiber, fiber sizing type and amount, andresin should be carefully documented prior to testing to avoidmisinterpretation of test results.7.1.1 Fiber and resin content should be measured andrecorded using at least one unit cell of the material from a
40、t leastone location in each panel from which test specimens aremachined. Section 12 covers methods for measuring thesevalues.7.1.2 The following items should be documented each timea material is tested: fiber type, fiber diameter, fiber surfacetreatment or sizing type and amount, and resin type.7.2
41、Fabric DefinitionDue to the limitless possibilitiesinvolved in placing yarns during the weaving and braidingoperations, it is important to carefully document the yarncounts (or yarn sizes), yarn spacings, yarn orientations, yarncontents, weave or braid pattern identification, and yarninterlocking th
42、rough the preform thickness. Such documenta-tion is required to properly define the textile unit cell and alsoto properly identify the textile material that was tested and toavoid any possible misinterpretations of the test results.7.3 Process DefinitionProcessing techniques can affectfiber orientat
43、ion, void content, and state of polymerization.These factors can in turn influence material property test resultssignificantly. Each of these items should be defined anddocumented prior to testing to avoid misinterpretation of thetest results.7.3.1 The amount of debulking of the preform duringproces
44、sing can affect the fiber volume and also the fiberorientation through the thickness. In-plane fiber orientation canbe adversely affected during the placement of the preform inthe mold. Both overall and local variations in fiber orientationshould be documented.7.3.2 As a minimum the following proces
45、s conditionsshould be documented for each material tested: preformthickness, preform tackifier (or resin compatible binder) used,molding technique, molding temperature, molding pressure,molding time, and panel dimensions.8. Strain Gage Selection8.1 The surface preparation, gage installation, lead wi
46、reconnection, and verification check procedures described in TestMethods E251 and Guide E1237 are applicable to textilecomposites and should be used in the application of bondedresistance strain gages.8.2 The strain gage size selected for each particular textilecomposite should take into considerati
47、on the size of the unitcell for the particular textile composite architecture. EachFIG. 4 Smallest Unit Cell Length for Layer-to-Layer Angle-Interlock WeaveD6856/D6856M 03 (2016)4different textile architecture has an independent unit cell size,which defines the extent of inhomogeniety in the displac
48、ementfields. The size of the gage should be large enough relative tothe textile unit cell to provide a reliable measurement of theaverage strain magnitude. It is recommended for most textilearchitectures that the gage length and width should, at aminimum, equal the length and width of the smallest u
49、nit cell.This applies to specimens loaded in the axial fiber direction(longitudinal direction) and to specimens loaded perpendicularto the axial fibers (transverse direction). For stitchedcomposites, it is recommended that the gage length and widthshould, at a minimum, equal the stitch spacing and stitch pitch,respectively. The user is also referred to Ref (3) for furtherguidance.9. Sampling and Test Specimens9.1 SamplingIt is recommended that at least five speci-mens be tested per series unless valid results can be obtainedusing less specimens, such as by using a desig
