1、Designation: D 6856 03 (Reapproved 2008)Standard Guide forTesting Fabric-Reinforced “Textile” Composite Materials1This standard is issued under the fixed designation D 6856; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、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.INTRODUCTIONA variety of fabric-reinforced composite materials have been developed for use in aerospace,automotive, and other a
3、pplications. 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 of the reinf
4、orcement, 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. Textile composites
5、 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 pattern of the
6、 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 current ASTM standards developed for highperformance composites. In many cases, the current ASTM standards are quite adequate if p
7、roperattention 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 considerations neces
8、sary 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 applicable to t
9、he 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 Assist the
10、 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 intent of this g
11、uide 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 SI units are to be regarded as thestandard. The values in parentheses are for information only.1.5 This standard does not p
12、urport 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 requirements prior to use.2. Referenced Documents2.1 ASTM Standards:
13、2D 790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating MaterialsD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 2344/D 2344M Test Method for Short-Beam Str
14、ength ofPolymer Matrix Composite Materials and Their Laminates1This 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, 2008. Published December 2008.
15、Originallyapproved in 2003. Last previous edition approved in 2003 as D 6856-03.2For 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
16、onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite MaterialsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3410/D 3410M
17、Test Method for Compressive Propertiesof Polymer Matrix Composite Materials with UnsupportedGage Section by Shear LoadingD 3479/D 3479M Test Method for Tension-Tension Fatigueof Polymer Matrix Composite MaterialsD 3518/D 3518M Test Method for In-Plane Shear Responseof Polymer Matrix Composite Materi
18、als by Tensile Test ofa 645 LaminateD 3846 Test Method for In-Plane Shear Strength of Rein-forced PlasticsD 3878 Terminology for Composite MaterialsD 4255/D 4255M Test Method for In-Plane Shear Proper-ties of Polymer Matrix Composite Materials by the RailShear MethodD 5229/D 5229M Test Method for Mo
19、isture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsD 5379/D 5379M Test Method for Shear Properties ofComposite Materials by the V-Notched Beam MethodD 5528 Test Method for Mode I Interlaminar FractureToughness of Unidirectional Fiber-Reinforced PolymerMatr
20、ix CompositesD 5766/D 5766M Test Method for Open-Hole TensileStrength of Polymer Matrix Composite LaminatesD 5961/D 5961M Test Method for Bearing Response ofPolymer Matrix Composite LaminatesD6115 Test Method for Mode I Fatigue DelaminationGrowth Onset of Unidirectional Fiber-Reinforced PolymerMatri
21、x CompositesD 6415 Test Method for Measuring the Curved BeamStrength of a Fiber-Reinforced Polymer-Matrix CompositeD 6272 Test Method for Flexural Properties of Unrein-forced and Reinforced Plastics and Electrical InsulatingMaterials by Four-Point BendingD 6484/D 6484M Test Method for Open-Hole Comp
22、ressiveStrength of Polymer Matrix Composite LaminatesD 6641/D 6641M Test Method for Determining the Com-pressive Properties of Polymer Matrix Composite Lami-nates Using a Combined Loading Compression (CLC) TestFixtureD 6671/D 6671M Test Method for Mixed Mode I-Mode IIInterlaminar Fracture Toughness
23、of Unidirectional FiberReinforced Polymer Matrix CompositesE6 Terminology Relating to Methods of Mechanical Test-ingE 122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the Average for a Characteristicof a Lot or ProcessE 251 Test Methods for Performance Characteristics o
24、fMetallic Bonded Resistance Strain GagesE 456 Terminology Relating to Quality and StatisticsE 1237 Guide for Installing Bonded Resistance StrainGages3. Terminology3.1 DefinitionsDefinitions used in this guide are definedby various ASTM methods. Terminology D 3878 defines termsrelating to high-modulu
25、s fibers and their composites. Termi-nology D 883 defines terms relating to plastics. TerminologyE6defines terms relating to mechanical testing. TerminologyE 456 defines terms relating to statistics. In the event of aconflict between definitions of terms, Terminology D 3878shall have precedence over
26、 the other standards. Terms relatingspecifically to 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 def
27、ined as the smallest section of architecture3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.FIG. 1 Smallest Unit Cells for Plain Weave and 5-Harness Satin Weave ArchitecturesD 6856 03 (2008)2required to repeat the textile pattern (see Figs. 1-4). Handl
28、ingand 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 bedefined for a given textile architecture. For example, F
29、ig. 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 guide, to beconsistent, the term “unit cell” is used t
30、o 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 rotations) of the unit cell. Examples of thesmallest unit cells
31、 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 cellwidth is the distance between two adjacent warp stuffer yarncolumns (
32、in the fill yarn direction) and the smallest unit cellheight is the consolidated woven composite thickness.4. Significance and Use4.1 This guide is intended to serve as a reference for thetesting of textile composite materials.4.2 The use of this guide ensures that proper considerationis given to th
33、e 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 Guide5.1 Special testing considerations unique to textile compos-ite
34、s 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 TestSpecimens; Section 10 on Test Specimen Conditioning; Sec-tion 11
35、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 13identifies areas where revised or new standards are needed fort
36、extile composites.6. Procedure for Use6.1 Review Sections 7-12 to become familiar with thespecial testing considerations for textile composites.6.2 Follow the recommended ASTM test method identifiedin Section 12 for determining a required property but refer backto this guide for recommendations on t
37、est 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 property test results. Each constitu-ent, that is, the fiber, fi
38、ber sizing type and amount, and resinshould 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 at leastone location in each panel from which test specimens a
39、remachined. 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 Fabric DefinitionDue to the limitless possibilitiesinvolved i
40、n 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 yarnFIG. 2 Smallest Unit Cells for a 2-D Braid and a 232, 2-D Triaxial BraidD 68
41、56 03 (2008)3interlocking through 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 techniq
42、ues can affectfiber orientation, 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
43、 of the preform duringprocessing 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
44、minimum the following process 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
45、, gage installation, lead wireconnection, and verification check procedures described in TestMethods E 251 and Guide E 1237 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 textilecomposit
46、e should take into consideration the size of the unitcell for the particular textile composite architecture. Eachdifferent textile architecture has an independent unit cell size,which defines the extent of inhomogeniety in the displacementfields. The size of the gage should be large enough relative
47、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 unit cell.This applies to specimens loaded in the axial fiber direc
48、tion(longitudinal direction) and to specimens loaded perpendicularto the axial fibers (transverse direction). For stitched compos-ites, it is recommended that the gage length and width should,at a minimum, equal the stitch spacing and stitch pitch,respectively. The user is also referred to Ref (3) f
49、or 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 designed experiment.For statistically significant data, the procedure outlined inPractice E 122 should be used and the method of samplingshould be reported.9.2 Specimen GeometryThe test specimen geometry shallbe in accordance with the corresponding ASTM test methodand the specimen geometry recommended in Section 12 foreach measured property. The recommended ratio of spec
