ASTM D6856/D6856M-03(2016)
(Guide)Standard Guide for Testing Fabric-Reinforced “Textile” Composite Materials
Standard Guide for Testing Fabric-Reinforced “Textile” Composite Materials
SIGNIFICANCE AND USE
4.1 This guide is intended to serve as a reference for the testing of textile composite materials.
4.2 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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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6856/D6856M − 03 (Reapproved 2016)
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.
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, 2016. Published September 2016. Originally
ɛ1 are to be regarded separately as standard. The values stated in
approved in 2003. Last previous edition approved in 2003 as D6856-03(2008) .
DOI: 10.1520/D6856_D6856M-03R16. 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
D6856/D6856M − 03 (2016)
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.
D6856/D6856M − 03 (2016)
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.
D6856/D6856M − 03 (2016)
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
D6856/D6856M − 03 (2016)
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
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6856/D6856M − 03 (Reapproved 2016)
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.
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
yarns 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 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, special care should be exercised in the use of the current ASTM standards developed for high
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, in some cases, current standards do not meet the needs for testing of the required properties.
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 Assist the user in selecting the best currently available
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 Ensure that proper consideration is given to the unique
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, 2016. Published September 2016. Originally
ɛ1
are to be regarded separately as standard. The values stated in
approved in 2003. Last previous edition approved in 2003 as D6856-03(2008) .
DOI: 10.1520/D6856_D6856M-03R16. 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
D6856/D6856M − 03 (2016)
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. D6272 Test 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/D6484M Test 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/D6641M Test 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/D6671M Test Method for Mixed Mode I-Mode II
2.1 ASTM Standards:
Interlaminar Fracture Toughness of Unidirectional Fiber
D790 Test Methods for Flexural Properties of Unreinforced
Reinforced Polymer Matrix Composites
and Reinforced Plastics and Electrical Insulating Materi-
E6 Terminology Relating to Methods of Mechanical Testing
als
E122 Practice for Calculating Sample Size to Estimate, With
D792 Test 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
D883 Terminology Relating to Plastics
E251 Test Methods for Performance Characteristics of Me-
D2344/D2344M Test Method for Short-Beam Strength of
tallic Bonded Resistance Strain Gages
Polymer Matrix Composite Materials and Their Laminates
E456 Terminology Relating to Quality and Statistics
D3039/D3039M Test Method for Tensile Properties of Poly-
E1237 Guide for Installing Bonded Resistance Strain Gages
mer Matrix Composite Materials
D3171 Test Methods for Constituent Content of Composite
3. Terminology
Materials
3.1 Definitions—Definitions used in this guide are defined
D3410/D3410M Test Method for Compressive Properties of
by various ASTM 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
nology D883 defines terms relating to plastics. Terminology E6
D3479/D3479M Test Method for Tension-Tension Fatigue
defines terms relating to mechanical testing. Terminology E456
of Polymer Matrix Composite Materials
defines terms relating to statistics. In the event of a conflict
D3518/D3518M Test Method for In-Plane Shear Response
between definitions of terms, Terminology D3878 shall have
of Polymer Matrix Composite Materials by Tensile Test of
precedence over the other standards. Terms relating specifically
a 645° Laminate
to textile composites are defined by Ref (1).
D3846 Test Method for In-Plane Shear Strength of Rein-
3.2 textile unit cell—In theory, textile composites have a
forced Plastics
D3878 Terminology for Composite Materials repeating geometrical pattern based on manufacturing param-
eters. This repeating pattern is often referred to as the materials
D4255/D4255M Test Method for In-Plane Shear Properties
of Polymer Matrix Composite Materials by the Rail Shear “unit cell.” It is defined as the smallest section of architecture
required to repeat the textile pattern (see Figs. 1-4). Handling
Method
D5229/D5229M Test Method for Moisture Absorption Prop- and processing can distort the “theoretical” unit cell. Param-
eters such as yarn size, yarn spacing, fabric construction, and
erties and Equilibrium Conditioning of Polymer Matrix
Composite Materials fiber angle may be used to calculate theoretical unit cell
dimensions. However, several different “unit cells” may be
D5379/D5379M Test Method for Shear Properties of Com-
posite Materials by the V-Notched Beam Method defined for a given textile architecture. For example, Fig. 2
shows two different unit cells for the braided architectures.
D5528 Test Method for Mode I Interlaminar Fracture Tough-
ness of Unidirectional Fiber-Reinforced Polymer Matrix Thus, unit cell definition can be somewhat subjective based on
varying interpretations of the textile architecture. The user is
Composites
D5766/D5766M Test Method for Open-Hole Tensile referred to Refs (1, 2) for further guidance. In this guide, to be
consistent, the term “unit cell” is used to refer to the smallest
Strength of Polymer Matrix Composite Laminates
D5961/D5961M Test Method for Bearing Response of Poly- unit cell for a given textile architecture. This smallest unit cell
mer Matrix Composite Laminates is defined as the smallest section of the textile architecture
required to replicate the textile pattern by using only in-plane
D6115 Test Method for Mode I Fatigue Delamination
Growth Onset of Unidirectional Fiber-Reinforced Poly- translations (and no rotations) of the unit cell. Examples of the
smallest unit cells for some of the commonly used textile
mer Matrix Composites
D6415 Test Method for Measuring the Curved Beam composites 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 by
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 The boldface numbers in parentheses refer to the list of references at the end of
the ASTM website. this standard.
D6856/D6856M − 03 (2016)
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.
D6856/D6856M − 03 (2016)
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 11 on Report of Results; and Section 12 on Recommended
These factors can in turn influence material property test results
Test Methods.
significantly. Each of these items should be defined and
5.2 Recommended ASTM 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.
orientation through the thickness. In-plane fiber orientation can
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 Sections 7 – 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
6.2 Follow the recommended ASTM test method identified should be documented for each material tested: preform
thickness, preform tackifier (or resin compatible binder) used,
in Section 12 for determining a required property but refer back
to this guide for recommendations on test specimen geometry, molding technique, molding temperature, molding pressure,
molding time, and panel dimensions.
strain measurement, and reporting of results.
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, and verification check procedures described in Test
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
recorded using at least one unit cell of the material from at least cell for the particular textile composite architecture. Each
D6856/D6856M − 03 (2016)
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
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: D6856/D6856M − 03 (Reapproved 2008) D6856/D6856M − 03 (Reapproved
2016)
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
yarns 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 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, special care should be exercised in the use of the current ASTM standards developed for high
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, in some cases, current standards do not meet the needs for testing of the required properties.
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 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.
This guide is under the jurisdiction of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommittee D30.04 on Lamina and Laminate
Test Methods.
Current edition approved Sept. 1, 2008Sept. 1, 2016. Published December 2008September 2016. Originally approved in 2003. Last previous edition approved in 2003 as
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D6856D6856-03(2008) -03. DOI: 10.1520/D6856_D6856M-03R08E01.10.1520/D6856_D6856M-03R16.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6856/D6856M − 03 (2016)
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.
2. Referenced Documents
2.1 ASTM Standards:
D790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D2344/D2344M Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their Laminates
D3039/D3039M Test Method for Tensile Properties of Polymer Matrix Composite Materials
D3171 Test Methods for Constituent Content of Composite Materials
D3410/D3410M Test Method for Compressive Properties of Polymer Matrix Composite Materials with Unsupported Gage
Section by Shear Loading
D3479/D3479M Test Method for Tension-Tension Fatigue of Polymer Matrix Composite Materials
D3518/D3518M Test Method for In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a 645°
Laminate
D3846 Test Method for In-Plane Shear Strength of Reinforced Plastics
D3878 Terminology for Composite Materials
D4255/D4255M Test Method for In-Plane Shear Properties of Polymer Matrix Composite Materials by the Rail Shear Method
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
D5379/D5379M Test Method for Shear Properties of Composite Materials by the V-Notched Beam Method
D5528 Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites
D5766/D5766M Test Method for Open-Hole Tensile Strength of Polymer Matrix Composite Laminates
D5961/D5961M Test Method for Bearing Response of Polymer Matrix Composite Laminates
D6115 Test Method for Mode I Fatigue Delamination Growth Onset of Unidirectional Fiber-Reinforced Polymer Matrix
Composites
D6415 Test Method for Measuring the Curved Beam Strength of a Fiber-Reinforced Polymer-Matrix Composite
D6272 Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials by
Four-Point Bending
D6484/D6484M Test Method for Open-Hole Compressive Strength of Polymer Matrix Composite Laminates
D6641/D6641M Test Method for Compressive Properties of Polymer Matrix Composite Materials Using a Combined Loading
Compression (CLC) Test Fixture
D6671/D6671M Test Method for Mixed Mode I-Mode II Interlaminar Fracture Toughness of Unidirectional Fiber Reinforced
Polymer Matrix Composites
E6 Terminology Relating to Methods of Mechanical Testing
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
E251 Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
E456 Terminology Relating to Quality and Statistics
E1237 Guide for Installing Bonded Resistance Strain Gages
3. Terminology
3.1 Definitions—Definitions used in this guide are defined by various ASTM methods. Terminology D3878 defines terms
relating to high-modulus fibers and their composites. Terminology D883 defines terms relating to plastics. Terminology E6 defines
terms relating to mechanical testing. Terminology E456 defines terms relating to statistics. In the event of a conflict between
definitions of terms, Terminology D3878 shall have precedence over the other standards. Terms relating specifically to textile
composites are defined by Ref (1).
3.2 textile unit cell—In theory, textile composites have a repeating geometrical pattern based on manufacturing parameters. This
repeating pattern is often referred to as the materials “unit cell.” It is defined as the smallest section of architecture required to
repeat the textile pattern (see Figs. 1-4). Handling and processing can distort the “theoretical” unit cell. Parameters such as yarn
size, yarn spacing, fabric construction, and fiber angle may be used to calculate theoretical unit cell dimensions. However, several
different “unit cells” may be defined for a given textile architecture. For example, Fig. 2 shows two different unit cells for the
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 the ASTM website.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
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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
braided architectures. Thus, unit cell definition can be somewhat subjective based on varying interpretations of the textile
architecture. The user is referred to Refs (1, 2) for further guidance. In this guide, to be consistent, the term “unit cell” is used to
refer to the smallest unit cell for a given textile architecture. This smallest unit cell is defined as the smallest section of the textile
architecture required to replicate the textile pattern by using only in-plane translations (and no rotations) of the unit cell. Examples
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FIG. 4 Smallest Unit Cell Length for Layer-to-Layer Angle-Interlock Weave
of the smallest unit cells for some of the commonly used textile composites 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 by the undulating pattern of the warp yarns. The smallest unit cell
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.
4. Significance and Use
4.1 This guide is intended to serve as a reference for the testing of textile composite materials.
4.2 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.
5. Summary of Guide
5.1 Special testing considerations unique to textile composites are identified and discussed. Recommendations for handling
these considerations are provided. Special considerations covered are included in Section 7 on Material Definition; Section 8 on
Gage Selection; Section 9 on Sampling and Test Specimens; Section 10 on Test Specimen Conditioning; Section 11 on Report of
Results; and Section 12 on Recommended Test Methods.
5.2 Recommended ASTM test methods applicable to textile composites and any special considerations are provided in Section
12 for mechanical and physical properties. Section 13 identifies areas where revised or new standards are needed for textile
composites.
6. Procedure for Use
6.1 Review Sections 7 – 12 to become familiar with the special testing considerations for textile composites.
6.2 Follow the recommended ASTM test method identified in Section 12 for determining a required property but refer back to
this guide for recommendations on test specimen geometry, strain measurement, and reporting of results.
7. Material Definition
7.1 Constituent Definition—Variations in type and amount of sizing on the fibers can significantly influence fabric quality and
subsequently material property test results. Each constituent, that is, the fiber, fiber sizing type and amount, and resin should be
carefully documented prior to testing to avoid misinterpretation of test results.
7.1.1 Fiber and resin content should be measured and recorded using at least one unit cell of the material from at least one
location in each panel from which test specimens are machined. Section 12 covers methods for measuring these values.
7.1.2 The following items should be documented each time a material is tested: fiber type, fiber diameter, fiber surface treatment
or sizing type and amount, and resin type.
7.2 Fabric Definition—Due to the limitless possibilities involved in placing yarns during the weaving and braiding operations,
it is important to carefully document the yarn counts (or yarn sizes), yarn spacings, yarn orientations, yarn contents, weave or braid
pattern identification, and yarn interlocking through the preform thickness. Such documentation is required to properly define the
textile unit cell and also to properly identify the textile material that was tested and to avoid any possible misinterpretations of the
test results.
7.3 Process Definition—Processing techniques can affect fiber orientation, void content, and state of polymerization. These
factors can in turn influence material property test results significantly. Each of these items should be defined and documented prior
to testing to avoid misinterpretation of the test results.
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7.3.1 The amount of debulking of the preform during processing can affect the fiber volume and also the fiber orientation
through the thickness. In-plane fiber orientation can be adversely affected during the placement of the preform in the mold. Both
overall and local variations in fiber orientation should be documented.
7.3.2 As a minimum the following process conditions should be documented for each material tested: preform thickness,
preform tackifier (or resin compatible binder) used, molding technique, molding temperature, molding pressure, molding time, and
panel dimensions.
8. Strain Gage Selection
8.1 The surface preparation, gage installation, lead wire connection, and verification check procedures described in Test
Methods E251 and Guide E1237 are applicable to textile composites and should be used in the application of bonded resistance
strain gages.
8.2 The strain gage size selected for each particular textile composite should take into consideration the size of the unit cell for
the p
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