ASTM D6856/D6856M-23

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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
1.4.1 Within the text the inch-pound units are shown in brackets.  
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, health, and environmental practices and determine the applicability of regulatory requirements prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 59.080.30 - Textile fabrics
• Technical Committee: D30 - Composite Materials
• Drafting Committee: D30.04 - Lamina and Laminate Test Methods

Relations

• Replaces: ASTM D6856/D6856M-03(2016) - Standard Guide for Testing Fabric-Reinforced “Textile” Composite Materials
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D6641/D6641M-23 - Standard Test Method for Compressive Properties of Polymer Matrix Composite Materials Using a Combined Loading Compression (CLC) Test Fixture
• Effective Date: 15-Nov-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E456-13a(2022) - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D6641/D6641M-16e2 - Standard Test Method for Compressive Properties of Polymer Matrix Composite Materials Using a Combined Loading Compression (CLC) Test Fixture
• Effective Date: 01-Nov-2016
• Refers: ASTM D3846-08(2015) - Standard Test Method for In-Plane Shear Strength of Reinforced Plastics (Withdrawn 2024)
• Effective Date: 01-Sep-2015
• Referred By: ASTM C1359-18e1 - Standard Test Method for Monotonic Tensile Strength Testing of Continuous Fiber-Reinforced Advanced Ceramics With Solid Rectangular Cross Section Test Specimens at Elevated Temperatures
• Effective Date: 01-Nov-2023
• Referred By: ASTM C1869-18(2023) - Standard Test Method for Open-Hole Tensile Strength of Fiber-Reinforced Advanced Ceramic Composites
• Effective Date: 01-Nov-2023
• Referred By: ASTM C1341-13(2023) - Standard Test Method for Flexural Properties of Continuous Fiber-Reinforced Advanced Ceramic Composites
• Effective Date: 01-Nov-2023
• Referred By: ASTM C1358-18 - Standard Test Method for Monotonic Compressive Strength Testing of Continuous Fiber-Reinforced Advanced Ceramics with Solid Rectangular Cross Section Test Specimens at Ambient Temperatures
• Effective Date: 01-Nov-2023
• Referred By: ASTM C1425-19 - Standard Test Method for Interlaminar Shear Strength of 1D and 2D Continuous Fiber-Reinforced Advanced Ceramics at Elevated Temperatures
• Effective Date: 01-Nov-2023

Overview

ASTM D6856/D6856M-23 is the Standard Guide for Testing Fabric-Reinforced “Textile” Composite Materials, published by ASTM International. This guide serves as a comprehensive reference for the testing of textile composites that use fabric preforms-such as woven, braided, or stitched reinforcements-in the composite structure. It is designed to address the unique characteristics of textile composite materials and guide users in selecting the most appropriate ASTM test methods for their evaluation.

By following this guide, users benefit from increased accuracy and reliability in test results. The document outlines specific considerations for material definition, test specimen preparation, conditioning, and reporting, ensuring that textile composites are characterized and tested with methods tailored to their distinct properties.

Key Topics

• Special Testing Considerations: The guide highlights specific requirements for testing textile composites, including the influence of fabric architecture, yarn size, and unit cell definition on test outcomes.
• Material Documentation: Accurate documentation of fiber type, weave or braid pattern, yarn properties, and resin content is critical to avoid misinterpretation of test data.
• Test Method Selection: Recommendations are provided for selecting the best ASTM methods for measuring properties like tensile strength, compression, shear, flexural response, fatigue, and more.
• Specimen Preparation and Conditioning: Guidance is offered on selecting test specimen dimensions based on the textile unit cell, preconditioning specimens to moisture equilibrium, and ensuring correct environmental exposure prior to testing.
• Reporting Requirements: The guide outlines a comprehensive list of documentation items that must be included in test reports to assure full traceability and result accuracy.

Applications

ASTM D6856/D6856M-23 is highly relevant across industries utilizing advanced composite materials, including:

• Aerospace: Validation and quality assurance of woven or braided composite components for structural and non-structural use in aircraft and spacecraft.
• Automotive: Performance assessment of materials used in safety-critical and lightweight vehicle parts.
• Civil Engineering and Construction: Evaluation of fabric-reinforced panels and reinforcement systems for construction and infrastructure projects.
• Industrial Manufacturing: Testing and qualification of innovative composite materials for energy, marine, sports equipment, and other high-performance applications.

By adhering to this standard, organizations ensure consistent testing procedures, accurate material qualification, and global comparability of data.

Related Standards

For comprehensive testing of textile composites, ASTM D6856/D6856M-23 references and should be used in conjunction with numerous other ASTM test methods, including:

• ASTM D3039/D3039M – Tensile Properties of Polymer Matrix Composite Materials
• ASTM D6641/D6641M – Compressive Properties of Polymer Matrix Composite Materials
• ASTM D7078/D7078M, D5379/D5379M, D4255/D4255M – Shear Properties
• ASTM D7264/D7264M, D790 – Flexural Properties
• ASTM D3479/D3479M, D7774 – Fatigue Testing Methods
• ASTM D792 – Density and Specific Gravity by Displacement
• ASTM D3171 – Fiber Content
• ISO 19927 – Interlaminar Strength and Modulus (international applicability)
• ASTM D368, D5687/D5687M – Specimen Preparation and Machining

When current ASTM test methods do not fully address specialized needs, this guide indicates where adaptations or new development may be required, particularly for through-thickness and out-of-plane property testing.

---

Following ASTM D6856/D6856M-23 ensures thorough, accurate, and standardized testing of fabric-reinforced “textile” composite materials, supporting quality control and innovation across advanced manufacturing sectors. Adopting its guidelines enables proper test method selection, reliable data, and facilitates regulatory and international compliance.

Standards Content (Sample)

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 − 23
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, civil, construction, 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
included.
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
1.4 The values stated in either SI units or inch-pound units
Laminate Test Methods.
are to be regarded separately as standard. The values stated in
Current edition approved Nov. 1, 2023. Published November 2023. Originally
each system are not necessarily exact equivalents; therefore, to
approved in 2003. Last previous edition approved in 2016 as D6856 – 03 (2016).
DOI: 10.1520/D6856_D6856M-23. ensure conformance with the standard, each system shall be
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6856/D6856M − 23
used independently of the other, and values from the two Strength of Polymer Matrix Composite Laminates
systems shall not be combined. D5961/D5961M Test Method for Bearing Response of Poly-
1.4.1 Within the text the inch-pound units are shown in mer Matrix Composite Laminates
brackets. D6115 Test Method for Mode I Fatigue Delamination
Growth Onset of Unidirectional Fiber-Reinforced Poly-
1.5 This standard does not purport to address all of the
mer Matrix Composites
safety concerns, if any, associated with its use. It is the
D6415/D6415M Test Method for Measuring the Curved
responsibility of the user of this standard to establish appro-
Beam Strength of a Fiber-Reinforced Polymer-Matrix
priate safety, health, and environmental practices and deter-
Composite
mine the applicability of regulatory requirements prior to use.
D6484/D6484M Test Method for Open-Hole Compressive
1.6 This international standard was developed in accor-
Strength of Polymer Matrix Composite Laminates
dance with internationally recognized principles on standard-
D6641/D6641M Test Method for Compressive Properties of
ization established in the Decision on Principles for the
Polymer Matrix Composite Materials Using a Combined
Development of International Standards, Guides and Recom-
Loading Compression (CLC) Test Fixture
mendations issued by the World Trade Organization Technical
D6671/D6671M Test Method for Mixed Mode I-Mode II
Barriers to Trade (TBT) Committee.
Interlaminar Fracture Toughness of Unidirectional Fiber
Reinforced Polymer Matrix Composites
2. Referenced Documents
D7078/D7078M Test Method for Shear Properties of Com-
2.1 ASTM Standards:
posite Materials by V-Notched Rail Shear Method
D792 Test Methods for Density and Specific Gravity (Rela-
D7264/D7264M Test Method for Flexural Properties of
tive Density) of Plastics by Displacement
Polymer Matrix Composite Materials
D883 Terminology Relating to Plastics
D7291/D7291M Test Method for Through-Thickness “Flat-
D2344/D2344M Test Method for Short-Beam Strength of
wise” Tensile Strength and Elastic Modulus of a Fiber-
Polymer Matrix Composite Materials and Their Laminates
Reinforced Polymer Matrix Composite Material
D3039/D3039M Test Method for Tensile Properties of Poly-
D7774 Test Method for Flexural Fatigue Properties of Plas-
mer Matrix Composite Materials
tics
D3171 Test Methods for Constituent Content of Composite
E6 Terminology Relating to Methods of Mechanical Testing
Materials
E83 Practice for Verification and Classification of Exten-
D3410/D3410M Test Method for Compressive Properties of
someter Systems
Polymer Matrix Composite Materials with Unsupported
E122 Practice for Calculating Sample Size to Estimate, With
Gage Section by Shear Loading
Specified Precision, the Average for a Characteristic of a
D3479/D3479M Test Method for Tension-Tension Fatigue
Lot or Process
of Polymer Matrix Composite Materials
E251 Test Methods for Performance Characteristics of Me-
D3518/D3518M Test Method for In-Plane Shear Response
tallic Bonded Resistance Strain Gages
of Polymer Matrix Composite Materials by Tensile Test of
E456 Terminology Relating to Quality and Statistics
a 645° Laminate
E1237 Guide for Installing Bonded Resistance Strain Gages
D3846 Test Method for In-Plane Shear Strength of Rein-
2.2 Other Standards:
forced Plastics
ISO 19927 Fibre-reinforced plastic composites – Determi-
D3878 Terminology for Composite Materials
nation of interlaminar strength and modulus by double
D4255/D4255M Test Method for In-Plane Shear Properties
beam shear test
of Polymer Matrix Composite Materials by the Rail Shear
Method
3. Terminology
D5229/D5229M Test Method for Moisture Absorption Prop-
3.1 Definitions—Definitions used in this guide are defined
erties and Equilibrium Conditioning of Polymer Matrix
by various ASTM methods. Terminology D3878 defines terms
Composite Materials
relating to high-modulus fibers and their composites. Termi-
D5379/D5379M Test Method for Shear Properties of Com-
nology D883 defines terms relating to plastics. Terminology E6
posite Materials by the V-Notched Beam Method
defines terms relating to mechanical testing. Terminology E456
D5528 Test Method for Mode I Interlaminar Fracture Tough-
defines terms relating to statistics. In the event of a conflict
ness of Unidirectional Fiber-Reinforced Polymer Matrix
between definitions of terms, Terminology D3878 shall have
Composites
precedence over the other standards. Terms relating specifically
D5687/D5687M Guide for Preparation of Flat Composite
to textile composites are defined by Ref (1).
Panels with Processing Guidelines for Specimen Prepara-
tion 3.2 textile unit cell—In theory, textile composites have a
D5766/D5766M Test Method for Open-Hole Tensile repeating geometrical pattern based on manufacturing param-
eters. This repeating pattern is often referred to as the materi-
al’s “unit cell.” It is defined as the smallest section of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. 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 − 23
architecture required to repeat the textile pattern (see Figs. covered are included in Section 7 on Material Definition;
1-4). Handling and processing can distort the “theoretical” unit Section 8 on Gage Selection; Section 9 on Sampling and Test
cell. Parameters such as yarn size, yarn spacing, fabric Specimens; Section 10 on Test Specimen Conditioning; Sec-
construction, and fiber angle may be used to calculate theoreti- tion 11 on Report of Results; and Section 12 on Recommended
cal unit cell dimensions. However, several different “unit cells” Test Methods.
may be defined for a given textile architecture. For example,
5.2 Recommended ASTM test methods applicable to textile
Fig. 2 shows two different unit cells for the braided architec-
composites and any special considerations are provided in
tures. Thus, unit cell definition can be somewhat subjective
Section 12 for mechanical and physical properties. Section 13
based on varying interpretations of the textile architecture. The
identifies areas where revised or new standards are needed for
user is referred to Refs (1, 2) for further guidance. In this guide,
textile composites.
to be consistent, the term “unit cell” is used to refer to the
smallest unit cell for a given textile architecture. This smallest
6. Procedure for Use
unit cell is defined as the smallest section of the textile
6.1 Review Sections 7 – 12 to become familiar with the
architecture required to replicate the textile pattern by using
special testing considerations for textile composites.
only in-plane translations (and no rotations) of the unit cell.
Examples of the smallest unit cells for some of the commonly 6.2 Follow the recommended ASTM test method identified
used textile composites are shown in Figs. 1-4. For the 3-D in Section 12 for determining a required property but refer back
weaves in Figs. 3 and 4, the smallest unit cell length (as to this guide for recommendations on test specimen geometry,
indicated) is defined by the undulating pattern of the warp strain measurement, and reporting of results.
yarns. The smallest unit cell width is the distance between two
7. Material Definition
adjacent warp stuffer yarn columns (in the fill yarn direction)
and the smallest unit cell height is the consolidated woven
7.1 Constituent Definition—Variations in type and amount
composite thickness.
of sizing on the fibers can significantly influence fabric quality
and subsequently material property test results. Each
4. Significance and Use
constituent, that is, the fiber, fiber sizing type and amount, and
4.1 This guide is intended to serve as a reference for the
resin should be carefully documented prior to testing to avoid
testing of textile composite materials.
misinterpretation of test results.
7.1.1 Fiber and resin content should be measured and
4.2 The use of this guide ensures that proper consideration
recorded using at least one unit cell of the material from at least
is given to the unique characteristics of these materials in
one location in each panel from which test specimens are
testing. In addition, this guide also assists the user in selecting
machined. Section 12 covers methods for measuring these
the best currently available ASTM test method for measure-
values.
ment of commonly evaluated material properties.
7.1.2 The following items should be documented each time
5. Summary of Guide a material is tested: fiber type, fiber diameter, fiber surface
treatment or sizing type and amount, and resin type.
5.1 Special testing considerations unique to textile compos-
ites are identified and discussed. Recommendations for han- 7.2 Fabric Definition—Due to the limitless possibilities
dling these considerations are provided. Special considerations involved in placing yarns during the weaving and braiding
FIG. 1 Smallest Unit Cells for Plain Weave and 5-Harness Satin Weave Architectures
D6856/D6856M − 23
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
FIG. 4 Smallest Unit Cell Length for Layer-to-Layer Angle-Interlock Weave
operations, it is important to carefully document the yarn 7.3 Process Definition—Processing techniques can affect
counts (or yarn sizes), yarn spacings, yarn orientations, yarn fiber orientation, void content, and state of polymerization.
contents, weave or braid pattern identification, and yarn
These factors can in turn influence material property test results
interlocking through the preform thickness. Such documenta-
significantly. Each of these items should be defined and
tion is required to properly define the textile unit cell and also
documented prior to testing to avoid misinterpretation of the
to properly identify the textile material that was tested and to
test results.
avoid any possible misinterpretations of the test results.
D6856/D6856M − 23
7.3.1 The amount of debulking of the preform during width to unit cell width for a textile composite is 2:1. The
processing can affect the fiber volume and also the fiber larger of (1) the specimen width dictated by this recommended
orientation through the thickness. In-plane fiber orientation can ratio and (2) the specimen width recommended in the corre-
be adversely affected during the placement of the preform in sponding ASTM standard for the measured property, should be
the mold. Both overall and local variations in fiber orientation used to ensure that at least two unit cells are included within
should be documented. the specimen gage section.
7.3.2 As a minimum the following process conditions
9.3 Specimen Fabrication—The specimens may be molded
should be documented for each material tested: preform
individually without cut edges or machined from a plate.
thickness, preform tackifier (or resin compatible binder) used,
Machining of specimens from plates should be done in
molding technique, molding temperature, molding pressure,
accordance with Guide D5687/D5687M.
molding time, and panel dimensions.
10. Test Specimen Conditioning
8. Apparatus
10.1 The recommended pre-test condition is effective mois-
8.1 Strain Indicating Device—Strain data, if required, shall
ture equilibrium at a specific relative humidity as established
be determined by means of either a strain transducer or an
by Test Method D5229/D5229M; however, if the test requestor
extensometer. Attachment of the strain-indicating device to the
does not explicitly specify a pre-test conditioning environment,
specimen shall not cause damage to the specimen surface.
no conditioning is required and the test specimens may be
8.1.1 Bonded Resistance Strain Gage Selection—The sur-
tested as received.
face preparation, gage installation, lead wire connection, and
10.2 The pre-test specimen conditioning process, to include
verification check procedures described in Test Methods E251
specified environmental exposure levels and resulting moisture
and Guide E1237 are applicable to textile composites and
content, shall be reported with the test data.
should be used in the application of bonded resistance strain
gages.
NOTE 1—The term moisture, as used in Test Method D5229/D5229M,
includes not only the vapor of a liquid and its condensate, but the liquid
The strain gage size selected for each particular textile
itself in large quantities as for immersion.
composite should take into consideration the size of the unit
cell for the particular textile composite architecture. Each 10.3 If no explicit conditioning process is performed, the
different textile architecture has an independent unit cell size,
specimen conditioning process shall be reported as “uncondi-
which defines the extent of inhomogeniety in the displacement tioned” and moisture content as “unknown”.
fields. The size of the gage should be large enough relative to
11. Report
the textile unit cell to provide a reliable measurement of the
average strain magnitude. It is recommended for most textile
11.1 Standard Reporting—All of the normal reporting re-
architectures that the gage length and width should, at a
quirements of the ASTM standard recommended for use for the
minimum, equal the length and width of the smallest unit cell.
particular property should be followed.
This applies to specimens loaded in the axial fiber direction
11.2 Textile Composite Reporting—Sections 7 – 10 covered
(longitudinal direction) and to specimens loaded perpendicular
the special considerations for testing of textile composite
to the axial fibers (transverse direction). For stitched
materials. A recommended list of the items which should be
composites, it is recommended that the gage length and width
documented in test reports as a consequence of these consid-
should, at a minimum, equal the stitch spacing and stitch pitch,
erations follows. Neglecting to document any of these items
respectively. The user is also referred to Ref (3) for further
could result in misinterpretation of test results.
guidance.
11.2.1 Material Documentation:
8.1.2 Extensometers—Extensometers shall satisfy Practice
11.2.1.1 Fiber type,
E83 requirements for the strain range of interest and shall be
11.2.1.2 Fiber diameter,
calibrated over that strain range in accordance with Practice
11.2.1.3 Fiber surface treatment type and amount,
E83. The extensometer gage length selected should take into
11.2.1.4 Fiber content,
account the size of the unit cell for the particular textile
11.2.1.5 Preform fabric type (weave, braid, and so forth),
composite architectures as discussed in 8.1.1.
11.2.1.6 Fabric construction (plain weave, 2×2 triaxial
braid, angle-interlock weave, and so forth),
9. Sampling and Test Specimens
11.2.1.7 Yarn filament count or yarn size for each different
9.1 Sampling—It is recommended that at least five speci-
set of yarns used in the fabric (for example, warp, weft/fill,
mens be tested per series
...

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.
Designation: D6856/D6856M − 03 (Reapproved 2016) D6856/D6856M − 23
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, civil, construction, 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.
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, 2016Nov. 1, 2023. Published September 2016November 2023. Originally approved in 2003. Last previous edition approved in 20032016
ɛ1
as D6856-03(2008)D6856 – 03 (2016). . DOI: 10.1520/D6856_D6856M-03R16.10.1520/D6856_D6856M-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6856/D6856M − 23
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 beare not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be
used independently of the other. Combiningother, and values from the two systems may result in non-conformance with the
standard.shall not be combined.
1.4.1 Within the text the inch-pound units are shown in brackets.
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 healthsafety, health, and environmental practices and determine
the applicability of regulatory requirements prior to use.
1.6 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.
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
D5687/D5687M Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
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
D6415D6415/D6415M 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
D7078/D7078M Test Method for Shear Properties of Composite Materials by V-Notched Rail Shear Method
D7264/D7264M Test Method for Flexural Properties of Polymer Matrix Composite Materials
D7291/D7291M Test Method for Through-Thickness “Flatwise” Tensile Strength and Elastic Modulus of a Fiber-Reinforced
Polymer Matrix Composite Material
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D6856/D6856M − 23
D7774 Test Method for Flexural Fatigue Properties of Plastics
E6 Terminology Relating to Methods of Mechanical Testing
E83 Practice for Verification and Classification of Extensometer Systems
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
2.2 Other Standards:
ISO 19927 Fibre-reinforced plastic composites – Determination of interlaminar strength and modulus by double beam shear test
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 materialsmaterial’s “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 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
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.
FIG. 1 Smallest Unit Cells for Plain Weave and 5-Harness Satin Weave Architectures
The boldface numbers in parentheses refer to the list of references at the end of this standard.
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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
FIG. 4 Smallest Unit Cell Length for Layer-to-Layer Angle-Interlock Weave
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.
D6856/D6856M − 23
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.
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 particular textile composite architecture. Each different textile architecture has an independent unit cell size, which defines the
extent of inhomogeniety in the displacement fields. The size of the gage should be large enough relative to the textile unit cell to
D6856/D6856M − 23
provide a reliable measurement of the average strain magnitude. It is recommended for most textile architectures that the gage
length and width should, at a minimum, equal the length and width of the smallest unit cell. This applies to specimens loaded in
the axial fiber direction (longitudinal direction) and to specimens loaded perpendicular to the axial fibers (transverse direction). For
stitched composites, 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) for further guidance.
8. Apparatus
8.1 Strain Indicating Device—Strain data, if required, shall be determined by means of either a strain transducer or an
extensometer. Attachment of the strain-indicating device to the specimen shall not cause damage to the specimen surface.
8.1.1 Bonded Resistance Strain Gage Selection—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.
The strain gage size selected for each particular textile composite should take into consideration the size of the unit cell for the
particular textile composite architecture. Each different textile architecture has an independent unit cell size, which defines the
extent of inhomogeniety in the displacement fields. The size of the gage should be large enough relative to the textile unit cell to
provide a reliable measurement of the average strain magnitude. It is recommended for most textile architectures that the gage
length and width should, at a minimum, equal the length and width of the smallest unit cell. This applies to specimens loaded in
the axial fiber direction (longitudinal direction) and to specimens loaded perpendicular to the axial fibers (transverse direction). For
stitched composites, 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) for further guidance.
8.1.2 Extensometers—Extensometers shall satisfy Practice E83 requirements for the strain range of interest and shall be calibrated
over that strain range in accordance with Practice E83. The extensometer gage length selected should take into account the size
of the unit cell for the particular textile composite architectures as discussed in 8.1.1.
9. Sampling and Test Specimens
9.1 Sampling—It is recommended that at least five specimens be tested per series unless valid results can be obtained using less
specimens, such as by using a designed experiment. For statistically significant data, the procedure outlined in Practice E122
should be used and the method of sampling should be reported.
9.2 Specimen Geometry—The test specimen geometry shall be in accordance with the corresponding ASTM test method and the
specimen geometry recommended in Section 12 for each measured property. The recommended ratio of specimen width to unit
cell width for a textile composite is 2:1. The larger of (1) the specimen width dictated by this recommended ratio and (2) the
specimen width recommended in the corresponding ASTM standard for the measured property, should be used to ensure that at
least two unit cells are included within the specimen gage section.
9.3 Specimen Fabrication—The specimens may be molded individually without cut edges or machined from a plate after bonding
on tab material. If cut from a plate, precautions must be taken to avoid notches, undercuts, or rough edges. When machined, each
specimen should be saw cut oversized and groundplate. Machining of specimens from plates should be done in accordance with
Guide D5687/D5687Mto the final dimensions.
10. Test Specimen Conditioning
10.1 The recommended pre-test condition is effective moisture equilibrium at a specific relative humidity as established by Test
Method D5229/D5229M; however, if the test requestor does not explicitly specify a pre-test conditioning environment, no
conditioning is required and the test specimens may be tested as received.
10.2 Unless a different environment is required, the test specimens shall be conditioned in accordance with Procedure C of Test
Method The pre-test specimen conditioning process, to include specified environmental exposure levels and resulting moisture
content, shall be reported with the test data.D5229/D5229M. The specimens should be stored and tested at standard laboratory
conditions of 23 6 1°C [73.4 6 1.8°F] and 50 6 10 % relative humidity.
NOTE 1—The term moisture, as used in Test Method D5229/D5229M, includes not only the vapor of a liquid and its condensate, but the liquid itself in
large quantities as for immersion.
D6856/D
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