ASTM D6856/D6856M-03(2008)e1
(Guide)Standard Guide for Testing Fabric-Reinforced "Textile" Composite Materials
Standard Guide for Testing Fabric-Reinforced "Textile" Composite Materials
SIGNIFICANCE AND USE
This guide is intended to serve as a reference for the testing of textile composite materials.
The use of this guide ensures that proper consideration is given to the unique characteristics of these materials in testing. In addition, this guide also assists the user in selecting the best currently available ASTM test method for measurement of commonly evaluated material properties.
SCOPE
1.1 This guide is applicable to the testing of textile composites 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 unique characteristics of these materials in testing.
1.1.2 Assist the user in selecting the best currently available ASTM test method for the measurement of commonly evaluated material properties for this class of materials.
1.2 Areas where current ASTM test methods do not meet the needs for testing of textile composites are indicated.
1.3 It is not the intent of this guide to cover all test methods which could possibly be used for textile composites. Only the most commonly used and most applicable standards are included.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.
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Designation: D6856/D6856M − 03(Reapproved 2008)
Standard Guide for
Testing Fabric-Reinforced “Textile” Composite Materials
This standard is issued under the fixed designation D6856/D6856M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorially changed to a combined standard in September 2010.
INTRODUCTION
A variety of fabric-reinforced composite materials have been developed for use in aerospace,
automotive, and other applications. These composite materials are reinforced with continuous fiber
yarnsthatareformedintotwo-dimensionalorthree-dimensionalfabrics.Variousfabricconstructions,
such as woven, braided, stitched, and so forth, can be used to form the fabric reinforcement. Due to
the nature 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 greater
delamination resistance.Textile composites are also amenable to automated fabrication. However, the
microstructure (or fiber architecture) of a textile composite, which consists of interlacing yarns, can
lead to increased inhomogeneity of the local displacement fields in the laminate. Depending upon the
size of the yarns and the pattern of the weave or braid, the inhomogeneity within a textile composite
can be large compared to traditional tape laminates.
Thus,specialcareshouldbeexercisedintheuseofthecurrentASTMstandardsdevelopedforhigh
performance composites. In many cases, the current ASTM standards are quite adequate if proper
attention is given to the special testing considerations for textile composites covered in this guide.
However,insomecases,currentstandardsdonotmeettheneedsfortestingoftherequiredproperties.
This guide is intended to increase the user’s awareness of the special considerations necessary for the
testing of these materials. It also provides the user with recommended ASTM standards that are
applicable for evaluating textile composites. The specific properties for which current ASTM
standards might not apply are also highlighted in this guide.
1. Scope 1.1.2 Assisttheuserinselectingthebestcurrentlyavailable
ASTM test method for the measurement of commonly evalu-
1.1 This guide is applicable to the testing of textile com-
ated material properties for this class of materials.
posites fabricated using fabric preforms, such as weaves,
braids, stitched preforms, and so forth, as the reinforcement.
1.2 Areas where current ASTM test methods do not meet
The purpose of this guide is to:
the needs for testing of textile composites are indicated.
1.1.1 Ensurethatproperconsiderationisgiventotheunique
1.3 It is not the intent of this guide to cover all test methods
characteristics of these materials in testing.
which could possibly be used for textile composites. Only the
most commonly used and most applicable standards are
This guide is under the jurisdiction of ASTM Committee D30 on Composite
included.
Materials and is the direct responsibility of Subcommittee D30.04 on Lamina and
Laminate Test Methods.
1.4 The values stated in either SI units or inch-pound units
Current edition approved Sept. 1, 2008. Published December 2008. Originally
are to be regarded separately as standard. The values stated in
approved in 2003. Last previous edition approved in 2003 as D6856-03. DOI:
10.1520/D6856_D6856M-03R08E01. each system may not be exact equivalents; therefore, each
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6856/D6856M − 03 (2008)
system shall be used independently of the other. Combining Strength of a Fiber-Reinforced Polymer-Matrix Compos-
values from the two systems may result in non-conformance ite
with the standard. D6272Test Method for Flexural Properties of Unreinforced
and Reinforced Plastics and Electrical Insulating Materi-
1.5 This standard does not purport to address all of the
als by Four-Point Bending
safety concerns, if any, associated with its use. It is the
D6484/D6484MTest Method for Open-Hole Compressive
responsibility of the user of this standard to establish appro-
Strength of Polymer Matrix Composite Laminates
priate safety and health practices and determine the applica-
D6641/D6641MTest Method for Compressive Properties of
bility of regulatory requirements prior to use.
Polymer Matrix Composite Materials Using a Combined
Loading Compression (CLC) Test Fixture
2. Referenced Documents
D6671/D6671MTest Method for Mixed Mode I-Mode II
2.1 ASTM Standards:
Interlaminar Fracture Toughness of Unidirectional Fiber
D790Test Methods for Flexural Properties of Unreinforced
Reinforced Polymer Matrix Composites
and Reinforced Plastics and Electrical Insulating Materi-
E6Terminology Relating to Methods of MechanicalTesting
als
E122PracticeforCalculatingSampleSizetoEstimate,With
D792Test Methods for Density and Specific Gravity (Rela-
Specified Precision, the Average for a Characteristic of a
tive Density) of Plastics by Displacement
Lot or Process
D883Terminology Relating to Plastics
E251Test Methods for Performance Characteristics of Me-
D2344/D2344MTest Method for Short-Beam Strength of
tallic Bonded Resistance Strain Gages
PolymerMatrixCompositeMaterialsandTheirLaminates
E456Terminology Relating to Quality and Statistics
D3039/D3039MTestMethodforTensilePropertiesofPoly-
E1237Guide for Installing Bonded Resistance Strain Gages
mer Matrix Composite Materials
D3171Test Methods for Constituent Content of Composite
3. Terminology
Materials
3.1 Definitions—Definitions used in this guide are defined
D3410/D3410MTest Method for Compressive Properties of
by variousASTM methods. Terminology D3878 defines terms
Polymer Matrix Composite Materials with Unsupported
relating to high-modulus fibers and their composites. Termi-
Gage Section by Shear Loading
nologyD883definestermsrelatingtoplastics.TerminologyE6
D3479/D3479MTest Method for Tension-Tension Fatigue
definestermsrelatingtomechanicaltesting.TerminologyE456
of Polymer Matrix Composite Materials
defines terms relating to statistics. In the event of a conflict
D3518/D3518MTest Method for In-Plane Shear Response
between definitions of terms, Terminology D3878 shall have
ofPolymerMatrixCompositeMaterialsbyTensileTestof
precedenceovertheotherstandards.Termsrelatingspecifically
a 645° Laminate
to textile composites are defined by Ref (1).
D3846Test Method for In-Plane Shear Strength of Rein-
forced Plastics 3.2 textile unit cell—In theory, textile composites have a
repeating geometrical pattern based on manufacturing param-
D3878Terminology for Composite Materials
D4255/D4255MTest Method for In-Plane Shear Properties eters.Thisrepeatingpatternisoftenreferredtoasthematerials
“unit cell.” It is defined as the smallest section of architecture
of Polymer Matrix Composite Materials by the Rail Shear
Method required to repeat the textile pattern (see Figs. 1-4). Handling
and processing can distort the “theoretical” unit cell. Param-
D5229/D5229MTestMethodforMoistureAbsorptionProp-
erties and Equilibrium Conditioning of Polymer Matrix eters such as yarn size, yarn spacing, fabric construction, and
fiber angle may be used to calculate theoretical unit cell
Composite Materials
D5379/D5379MTest Method for Shear Properties of Com- dimensions. However, several different “unit cells” may be
defined for a given textile architecture. For example, Fig. 2
posite Materials by the V-Notched Beam Method
D5528TestMethodforModeIInterlaminarFractureTough- shows two different unit cells for the braided architectures.
Thus, unit cell definition can be somewhat subjective based on
ness of Unidirectional Fiber-Reinforced Polymer Matrix
Composites varying interpretations of the textile architecture. The user is
referred to Refs (1, 2) for further guidance. In this guide, to be
D5766/D5766M Test Method for Open-Hole Tensile
Strength of Polymer Matrix Composite Laminates consistent, the term “unit cell” is used to refer to the smallest
unit cell for a given textile architecture. This smallest unit cell
D5961/D5961MTestMethodforBearingResponseofPoly-
mer Matrix Composite Laminates is defined as the smallest section of the textile architecture
D6115Test Method for Mode I Fatigue Delamination required to replicate the textile pattern by using only in-plane
translations (and no rotations) of the unit cell. Examples of the
Growth Onset of Unidirectional Fiber-Reinforced Poly-
mer Matrix Composites smallest unit cells for some of the commonly used textile
compositesareshowninFigs.1-4.Forthe3-DweavesinFigs.
D6415 Test Method for Measuring the Curved Beam
3and4,thesmallestunitcelllength(asindicated)isdefinedby
the undulating pattern of the warp yarns.The smallest unit cell
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
the ASTM website. this standard.
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D6856/D6856M − 03 (2008)
FIG. 1 Smallest Unit Cells for Plain Weave and 5-Harness Satin Weave Architectures
FIG. 2 Smallest Unit Cells for a 2-D Braid and a 2×2, 2-D Triaxial Braid
FIG. 3 Smallest Unit Cell Length for Through-Thickness Angle-Interlock Weave
width is the distance between two adjacent warp stuffer yarn
columns (in the fill yarn direction) and the smallest unit cell
height is the consolidated woven composite thickness.
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D6856/D6856M − 03 (2008)
FIG. 4 Smallest Unit Cell Length for Layer-to-Layer Angle-Interlock Weave
4. Significance and Use one location in each panel from which test specimens are
machined. Section 12 covers methods for measuring these
4.1 This guide is intended to serve as a reference for the
values.
testing of textile composite materials.
7.1.2 The following items should be documented each time
4.2 The use of this guide ensures that proper consideration
a material is tested: fiber type, fiber diameter, fiber surface
is given to the unique characteristics of these materials in
treatment or sizing type and amount, and resin type.
testing. In addition, this guide also assists the user in selecting
7.2 Fabric Definition—Due to the limitless possibilities
the best currently available ASTM test method for measure-
involved in placing yarns during the weaving and braiding
ment of commonly evaluated material properties.
operations, it is important to carefully document the yarn
counts (or yarn sizes), yarn spacings, yarn orientations, yarn
5. Summary of Guide
contents, weave or braid pattern identification, and yarn
5.1 Special testing considerations unique to textile compos-
interlocking through the preform thickness. Such documenta-
ites are identified and discussed. Recommendations for han-
tion is required to properly define the textile unit cell and also
dling these considerations are provided. Special considerations
to properly identify the textile material that was tested and to
covered are included in Section 7 on Material Definition;
avoid any possible misinterpretations of the test results.
Section 8 on Gage Selection; Section 9 on Sampling and Test
7.3 Process Definition—Processing techniques can affect
Specimens; Section 10 on Test Specimen Conditioning; Sec-
fiber orientation, void content, and state of polymerization.
tion 11onReportofResults;andSection12onRecommended
Thesefactorscaninturninfluencematerialpropertytestresults
Test Methods.
significantly. Each of these items should be defined and
5.2 RecommendedASTM test methods applicable to textile
documented prior to testing to avoid misinterpretation of the
composites and any special considerations are provided in
test results.
Section 12 for mechanical and physical properties. Section 13
7.3.1 The amount of debulking of the preform during
identifies areas where revised or new standards are needed for
processing can affect the fiber volume and also the fiber
textile composites.
orientationthroughthethickness.In-planefiberorientationcan
be adversely affected during the placement of the preform in
6. Procedure for Use
the mold. Both overall and local variations in fiber orientation
6.1 Review Sections7–12 to become familiar with the
should be documented.
special testing considerations for textile composites.
7.3.2 As a minimum the following process conditions
should be documented for each material tested: preform
6.2 Follow the recommended ASTM test method identified
inSection12fordeterminingarequiredpropertybutreferback thickness, preform tackifier (or resin compatible binder) used,
molding technique, molding temperature, molding pressure,
to this guide for recommendations on test specimen geometry,
strain measurement, and reporting of results. molding time, and panel dimensions.
8. Strain Gage Selection
7. Material Definition
8.1 The surface preparation, gage installation, lead wire
7.1 Constituent Definition—Variations in type and amount
connection,andverificationcheckproceduresdescribedinTest
of sizing on the fibers can significantly influence fabric quality
Methods E251 and Guide E1237 are applicable to textile
and subsequently material property test results. Each
composites and should be used in the application of bonded
constituent, that is, the fiber, fiber sizing type and amount, and
resistance strain gages.
resin should be carefully documented prior to testing to avoid
misinterpretation of test results. 8.2 The strain gage size selected for each particular textile
7.1.1 Fiber and resin content should be measured and composite should take into consideration the size of the unit
recordedusingatleastoneunitcellofthematerialfromatleast cell for the particular textile composite architecture. Each
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D6856/D6856M − 03 (2008)
different textile architecture has an independent unit cell size, 11.2.1.1 Fiber type,
which defines the extent of inhomogeniety in the displacement 11.2.1.2 Fiber diameter,
fields. The size of the gage should be large enough relative to
11.2.1.3 Fiber surface treatment type and amount,
the textile unit cell to provide a reliable measurement of the 11.2.1.4 Fiber content,
average strain magnitude. It is recommended for most textile
11.2.1.5 Preform fabric type (weave, braid, and so forth),
architectures that the gage length and width shoul
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