1、Designation: D 6856 03Standard 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 of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 applications. Thes
3、e 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 reinforcement, these m
4、aterials 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 are also amenabl
5、e 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 weave or braid,
6、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 properattention is
7、 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 necessary for thetesti
8、ng 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 the testing of tex
9、tile 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 user in selectin
10、g 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 guide to cover all
11、 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 purport to address
12、 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:D 790 Test Method
13、s for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-als2D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by Displacement2D 883 Terminology Relating to Plastics21This guide is under the jurisdiction of ASTM Committee D30
14、 on CompositeMaterials and is the direct responsibility of Subcommittee D30.04 on Lamina andLaminate Test Methods.Current edition approved Jan. 10, 2003. Published February 2003.2Annual Book of ASTM Standards, Vol 08.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
15、cken, PA 19428-2959, United States.D 2344/D 2344M Test Method for Short-Beam Strength ofPolymer Matrix Composite Materials and Their Lami-nates3D 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite Materials3D 3171 Test Method for Constituent Content of CompositeMaterials3D 34
16、10/D 3410M Test Method for Compressive Propertiesof Polymer Matrix Composite Materials with UnsupportedGage Section by Shear Loading3D 3479/D 3479M Test Method for Tension-Tension Fatigueof Polymer Matrix Composite Materials3D 3518/D 3518M Test Method for In-Plane Shear Responseof Polymer Matrix Com
17、posite Materials by Tensile Test ofa 645 Laminate3D 3846 Test Method for In-Plane Shear Strength of Rein-forced Plastics4D 3878 Terminology for Composite Materials3D 4255/D 4255M Test Method for In-Plane Shear Proper-ties of Polymer Matrix Composite Materials by the RailShear Method3D 5229/D 5229M T
18、est Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite Materials3D 5379/D 5379M Test Method for Shear Properties ofComposite Materials by the V-Notched Beam Method3D 5528 Test Method for Mode I Interlaminar FractureToughness of Unidirectional Fiber-Rei
19、nforced PolymerMatrix Composites3D 5766/D 5766M Test Method for Open Hole TensileStrength of Polymer Matrix Composite Laminates3D 5961/D 5961M Test Method for Bearing Response ofPolymer Matrix Composite Laminates3D 6115 Test Method for Mode I Fatigue DelaminationGrowth Onset of Unidirectional Fiber-
20、Reinforced PolymerMatrix Composites3D 6415 Test Method for Measuring the Curved BeamStrength of a Fiber-Reinforced Polymer-Matrix Compos-ite3D 6272 Test Method for Flexural Properties of Unrein-forced and Reinforced Plastics and Electrical InsulatingMaterials by Four-Point Bending5D 6484/D 6484M Tes
21、t Method for Open-Hole CompressiveStrength of Polymer Matrix Composite Laminates3D 6641/D 6641M Test Method for Determining the Com-pressive Properties of Polymer Matrix Composite Lami-nates Using a Combined Loading Compression (CLC) TestFixture3D 6671 Test Method for Mixed Mode I-Mode II Interlami-
22、nar Fracture Toughness of Unidirectional Fiber ReinforcedPolymer Matrix Composites3E 6 Terminology Relating to Methods of Mechanical Test-ing6E 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, the Average for Charac-teristic of a Lot or Process7E 251 Test Method
23、s for Performance Characteristics ofMetallic Bonded Resistance Strain Gages6E 456 Terminology Relating to Quality and Statistics7E 1237 Guide for Installing Bonded Resistance StrainGages63. Terminology3.1 DefinitionsDefinitions used in this guide are definedby variousASTM methods. Terminology D 3878
24、 defines termsrelating to high-modulus fibers and their composites. Termi-nology D 883 defines terms relating to plastics. TerminologyE 6 defines terms relating to mechanical testing. TerminologyE 456 defines terms relating to statistics. In the event of aconflict between definitions of terms, Termi
25、nology D 3878shall have precedence over the other standards. Terms relatingspecifically to textile composites are defined by Ref (1).83.2 textile unit cellIn theory, textile composites have arepeating geometrical pattern based on manufacturing param-eters. This repeating pattern is often referred to
26、 as the materials“unit cell.” It is defined as the smallest section of architecturerequired 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 c
27、alculate theoretical unit celldimensions. However, several different “unit cells” may bedefined 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 t
28、he textile architecture. The user isreferred to Refs (1, 2) for further guidance. In this 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 architecturerequ
29、ired to replicate the textile pattern by using only in-planetranslations (and no rotations) 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
30、 defined bythe undulating pattern of the warp yarns. The smallest unit cellwidth 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.4. Significance and Use4.1 This guide is intended
31、 to serve as a reference for thetesting of textile composite materials.4.2 The 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 meth
32、od for measure-ment of commonly evaluated material properties.3Annual Book of ASTM Standards, Vol 15.03.4Annual Book of ASTM Standards, Vol 08.02.5Annual Book of ASTM Standards, Vol 08.03.6Annual Book of ASTM Standards, Vol 03.01.7Annual Book of ASTM Standards, Vol 14.02.8The boldface numbers in par
33、entheses refer to the list of references at the end ofthis standard.D68560325. Summary of Guide5.1 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
34、 Section 7 on Material Definition;Section 8 on Gage Selection; Section 9 on Sampling and TestFIG. 1 Smallest Unit Cells for Plain Weave and 5-Harness Satin Weave ArchitecturesFIG. 2 Smallest Unit Cells for a 2-D Braid and a 232, 2-D Triaxial BraidFIG. 3 Smallest Unit Cell Length for Through-Thicknes
35、s Angle-Interlock WeaveD6856033Specimens; 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 an
36、d physical properties. Section 13identifies areas where revised or new standards are needed fortextile 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 Sec
37、tion 12 for determining a required 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 q
38、ualityand subsequently material property test results. Each constitu-ent, that is, the fiber, fiber 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 o
39、ne unit cell of the material from at 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 t
40、ype and amount, and resin type.7.2 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 iden
41、tification, and yarninterlocking 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
42、techniques 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 de
43、bulking 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.
44、2 As a 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 prep
45、aration, 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 textilec
46、omposite 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 re
47、lative 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 fibe
48、r direction(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 Re
49、f (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 designed experiment.FIG. 4 Smallest Unit Cell Length for Layer-to-Layer Angle-Interlock WeaveD6856034For 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 geometr
