ASTM D2344/D2344M-22

Standard Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their Laminates

SIGNIFICANCE AND USE
5.1 In most cases, because of the complexity of internal stresses and the variety of failure modes that can occur in this specimen, it is not generally possible to relate the short-beam strength to any one material property. However, failures are normally dominated by resin and interlaminar properties, and the test results have been found to be repeatable for a given specimen geometry, material system, and stacking sequence  (4).  
5.2 Short-beam strength determined by this test method can be used for quality control and process specification purposes. It can also be used for comparative testing of composite materials, provided that failures occur consistently in the same mode (5) .  
5.3 This test method is not limited to specimens within the range specified in Section 8, but is limited to the use of a loading span length-to-specimen thickness ratio of 4.0 and a minimum specimen thickness of 2.0 mm [0.08 in.].
SCOPE
1.1 This test method determines the short-beam strength of high-modulus fiber-reinforced composite materials. The specimen is a short beam machined from a curved or a flat laminate up to 6.00 mm [0.25 in.] thick. The beam is loaded in three-point bending.  
1.2 Application of this test method is limited to continuous- or discontinuous-fiber-reinforced polymer matrix composites, for which the elastic properties are balanced and symmetric with respect to the longitudinal axis of the beam.  
1.3 Units—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.  
1.3.1 Within the text, the inch-pound units are shown in brackets.  
1.4 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 limitations prior to use.  
1.5 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: 14-Jul-2022
• ICS: 83.140.20 - Laminated sheets
• Technical Committee: D30 - Composite Materials
• Drafting Committee: D30.04 - Lamina and Laminate Test Methods

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D2734-23 - Standard Test Methods for Void Content of Reinforced Plastics
• Effective Date: 01-Oct-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D5229/D5229M-20 - Standard Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials
• Effective Date: 01-Mar-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D3878-19a - Standard Terminology for Composite Materials
• Effective Date: 15-Oct-2019
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D3878-19 - Standard Terminology for Composite Materials
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D2584-18 - Standard Test Method for Ignition Loss of Cured Reinforced Resins
• Effective Date: 15-Sep-2018
• Refers: ASTM E18-18 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Jul-2018

Overview

ASTM D2344/D2344M-22, published by ASTM International, is the Standard Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their Laminates. This standard outlines a three-point bending test to determine the short-beam strength of high-modulus, fiber-reinforced polymer matrix composites-key materials in aerospace, automotive, and other high-performance industries. The method is applicable to both continuous- and discontinuous-fiber composites with balanced and symmetric properties relative to the beam’s longitudinal axis.

Short-beam strength, as determined by this test, is crucial for assessing the quality and comparative performance of composite materials. Given the complexity of internal stresses and failure modes involved, results generally reflect resin and interlaminar properties rather than a single material characteristic. The method is widely recognized for its repeatability when specimen geometry and material configuration remain consistent.

Key Topics

• Test Method Summary: This test involves machining a short beam specimen from a flat or curved laminate (up to 6.00 mm thick) and loading it at the center in a three-point bending fixture until failure. The span length-to-thickness ratio must be 4.0, and thickness at least 2 mm [0.08 in.].

• Specimen Requirements:

  • Specimens must be balanced and symmetric in elastic properties.
  • Both multidirectional and unidirectional laminates can be tested, provided there is sufficient reinforcement along the beam’s span direction.

• Equipment and Calibration:

  • Use calibrated testing machines and fixtures, properly sized loading noses and supports, as well as accurate measurement devices for specimen dimensions.
  • Environmental conditioning chambers are needed if tests are conducted at controlled temperature or humidity.

• Reporting and Analysis:

  • Detailed reporting includes specimen dimensions, conditioning parameters, failure modes, load-displacement data, and statistical analysis such as mean, standard deviation, and coefficient of variation.

• Interpretation of Results:

  • Failures are usually related to resin or interlaminar characteristics, with a variety of possible failure modes. Consistent failure modes across tests are key for comparative purposes.

Applications

The ASTM D2344/D2344M-22 standard is employed in several practical scenarios:

• Quality Control: Ensuring production consistency by monitoring short-beam strength of manufacturing lots.
• Material Comparison: Evaluating and comparing new composite systems, formulations, or suppliers for suitability in demanding applications.
• Process Specification: Verifying adherence to processing parameters by assessing the mechanical integrity of finished composites.
• Product Development: Supporting the design and optimization of polymer matrix composites for maximized interlaminar strength and durability.
• Research and Development: Providing standardized data for material property databases and supporting the development and validation of modeling approaches.

Industries such as aerospace, defense, automotive, marine, and sporting goods depend on these methods to predict component reliability in service.

Related Standards

Key standards referenced within ASTM D2344/D2344M-22 include:

• ASTM D792: Density and Specific Gravity (Relative Density) of Plastics by Displacement
• ASTM D2584: Ignition Loss of Cured Reinforced Resins
• ASTM D2734: Void Content of Reinforced Plastics
• ASTM D3171: Constituent Content of Composite Materials
• ASTM D5229/D5229M: Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composites
• ASTM D5687/D5687M: Preparation of Flat Composite Panels and Processing Guidelines for Specimen Preparation
• ASTM E4: Force Calibration and Verification of Testing Machines

These related ASTM standards provide comprehensive methodologies for material identification, sample preparation, equipment calibration, and statistical evaluation-ensuring that results from ASTM D2344/D2344M-22 are robust and comparable across organizations.

---

Keywords: ASTM D2344, short-beam strength, polymer matrix composites, interlaminar shear, composite laminates, quality control, composite testing, fiber-reinforced materials, three-point bending test, composite standards.

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: D2344/D2344M −22
Standard Test Method for
Short-Beam Strength of Polymer Matrix Composite Materials
and Their Laminates
This standard is issued under the fixed designation D2344/D2344M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
1.1 This test method determines the short-beam strength of
2.1 ASTM Standards:
high-modulus fiber-reinforced composite materials. The speci-
D792Test Methods for Density and Specific Gravity (Rela-
men is a short beam machined from a curved or a flat laminate
tive Density) of Plastics by Displacement
up to 6.00 mm [0.25 in.] thick. The beam is loaded in
D883Terminology Relating to Plastics
three-point bending.
D2584Test Method for Ignition Loss of Cured Reinforced
Resins
1.2 Application of this test method is limited to continuous-
or discontinuous-fiber-reinforced polymer matrix composites, D2734TestMethodsforVoidContentofReinforcedPlastics
D3171Test Methods for Constituent Content of Composite
for which the elastic properties are balanced and symmetric
with respect to the longitudinal axis of the beam. Materials
D3878Terminology for Composite Materials
1.3 Units—The values stated in either SI units or inch-
D5229/D5229MTestMethodforMoistureAbsorptionProp-
pound units are to be regarded separately as standard. The
erties and Equilibrium Conditioning of Polymer Matrix
values stated in each system are not necessarily exact equiva-
Composite Materials
lents; therefore, to ensure conformance with the standard, each
D5687/D5687MGuide for Preparation of Flat Composite
system shall be used independently of the other, and values
Panels with Processing Guidelines for Specimen Prepara-
from the two systems shall not be combined.
tion
1.3.1 Within the text, the inch-pound units are shown in
E4Practices for Force Calibration and Verification of Test-
brackets.
ing Machines
1.4 This standard does not purport to address all of the
E6Terminology Relating to Methods of Mechanical Testing
safety concerns, if any, associated with its use. It is the
E18Test Methods for Rockwell Hardness of Metallic Ma-
responsibility of the user of this standard to establish appro-
terials
priate safety, health, and environmental practices and deter-
E122PracticeforCalculatingSampleSizetoEstimate,With
mine the applicability of regulatory limitations prior to use.
Specified Precision, the Average for a Characteristic of a
1.5 This international standard was developed in accor-
Lot or Process
dance with internationally recognized principles on standard-
E177Practice for Use of the Terms Precision and Bias in
ization established in the Decision on Principles for the
ASTM Test Methods
Development of International Standards, Guides and Recom-
E456Terminology Relating to Quality and Statistics
mendations issued by the World Trade Organization Technical
E691Practice for Conducting an Interlaboratory Study to
Barriers to Trade (TBT) Committee.
Determine the Precision of a Test Method
This test method 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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 15, 2022. Published August 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1965. Last previous edition approved in 2016 as D2344/D2344M–16. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D2344_D2344M-22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2344/D2344M − 22
3. Terminology
3.1 Definitions—Terminology D3878 defines the terms re-
lating to high-modulus fibers and their composites. Terminol-
ogy D883 defines terms relating to plastics. Terminology E6
definestermsrelatingtomechanicaltesting.TerminologyE456
and Practice E177 define terms relating to statistics. In the
event of a conflict between definitions, Terminology D3878
shall have precedence over the other documents.
NOTE 1—If the term represents a physical quantity, its analytical
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
fundamental dimension form, using the following ASTM standard sym-
bology for fundamental dimensions, shown within square brackets: [M]
formass,[L]forlength,[T]fortime,[Θ]forthermodynamictemperature,
and[ nd]fornondimensionalquantities.Useofthesesymbolsisrestricted
to analytical dimensions when used with square brackets, as the symbols
may have other definitions when used without the brackets.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 short-beam strength, n—the shear stress as calculated
in Eq 1, developed at the specimen mid-plane at the failure
event specified in 11.6.
3.2.1.1 Discussion—Althoughshearisthedominantapplied
loading in this test method, the internal stresses are complex,
andavarietyoffailuremodescanoccur.Elasticitysolutionsby
Berg et al (1) , Whitney (2), and Sullivan and Van Oene (3)
have all demonstrated inadequacies in classical beam theory in
defining the stress state in the short-beam configuration.These
solutions show that the parabolic shear-stress distribution as
predicted by Eq 1 only occurs, and then not exactly, on planes
NOTE1—DrawinginterpretationperANSIY14.5-1982andANSI/ASM
midway between the loading nose and support points. Away B46.1-1986.
fromtheseplanes,thestressdistributionsbecomeskewed,with NOTE 2—Ply orientation tolerance 60.5° relative to –B–.
FIG. 1 Flat Specimen Configuration (SI)
peak stresses occurring near the loading nose and support
points. Of particular significance is the stress state local to the
two supports that allow lateral motion, the load being applied
loading nose in which the severe shear-stress concentration
by means of a loading nose directly centered on the midpoint
combined with transverse and in-plane compressive stresses
of the test specimen.
has been shown to initiate failure. However, for the more
ductile matrices, plastic yielding may alleviate the situation
5. Significance and Use
under the loading nose (1) and allow other failure modes to
5.1 In most cases, because of the complexity of internal
occur such as bottom surface fiber tension (2). Consequently,
stresses and the variety of failure modes that can occur in this
unless mid-plane interlaminar failure has been clearly
specimen, it is not generally possible to relate the short-beam
observed, the short-beam strength determined from this test
strength to any one material property. However, failures are
method cannot be attributed to a shear property, and the use of
normally dominated by resin and interlaminar properties, and
Eq 1 will not yield an accurate value for shear strength.
the test results have been found to be repeatable for a given
3.3 Symbols:
specimen geometry, material system, and stacking sequence
b—specimen width
(4).
CV—sample coefficient of variation (in percent)
5.2 Short-beam strength determined by this test method can
sbs
F —short-beam strength
be used for quality control and process specification purposes.
h—specimen thickness
It can also be used for comparative testing of composite
n—number of specimens
materials, provided that failures occur consistently in the same
P —maximum load observed during the test
m
mode (5).
x—measuredorderivedpropertyforanindividualspecimen
i
5.3 This test method is not limited to specimens within the
from the sample population
range specified in Section 8, but is limited to the use of a
x¯—sample mean (average)
loading span length-to-specimen thickness ratio of 4.0 and a
4. Summary of Test Method minimum specimen thickness of 2.0 mm [0.08 in.].
4.1 The short-beam test specimens (Figs. 1-4) are center-
6. Interferences
loaded as shown in Figs. 5 and 6. The specimen ends rest on
6.1 Accurate reporting of observed failure modes is essen-
tial for meaningful data interpretation, in particular, the detec-
tion of initial damage modes.
D2344/D2344M − 22
for measuring width and length. The use of alternative mea-
surement devices is permitted if specified (or agreed to) by the
test requestor and reported by the testing laboratory. The
accuracy of the instrument(s) shall be suitable for reading
within1%ofthe specimen dimensions. For typical specimen
geometries, an instrument with an accuracy of 60.0025 mm
[60.0001 in.] is adequate for thickness measurements, while
an instrument with an accuracy of 60.025 mm [60.001 in.] is
adequate for measurement of width and length.
7.4 Conditioning Chamber—When conditioning materials
at nonlaboratory environments, a temperature/vapor-level-
controlledenvironmentalconditioningchamberisrequiredthat
shall be capable of maintaining the required temperature to
within 63°C(65°F) and the required vapor level to within
63%. Chamber conditions shall be monitored either on an
automated continuous basis or on a manual basis at regular
intervals.
7.5 Environmental Test Chamber—An environmental test
chamber is required for test environments other than ambient
testing laboratory conditions.This chamber shall be capable of
maintaining the test specimen at the required test environment
during the mechanical test method.
8. Sampling and Test Specimens
8.1 Sampling—Test at least five specimens per test condi-
tionunlessvalidresultscanbegainedthroughtheuseoffewer
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/
specimens, as in the case of a designed experiment. For
ASME B46.1-1986.
statistically significant data, consult the procedures outlined in
NOTE 2—Ply orientation tolerance 60.5° relative to –B–.
Practice E122. Report the method of sampling.
FIG. 2 Flat Specimen Configuration (Inch Pound)
8.2 Geometry:
8.2.1 Laminate Configurations—Both multidirectional and
7. Apparatus
pure unidirectional laminates can be tested, provided that there
are at least 10% 0° fibers in the span direction of the beam
7.1 Testing Machine, properly calibrated, which can be
(preferablywelldistributedthroughthethickness),andthatthe
operated at a constant rate of crosshead motion, and which the
laminates are both balanced and symmetric with respect to the
error in the loading system shall not exceed 61%. The
span direction of the beam.
load-indicating mechanism shall be essentially free of inertia
8.2.2 Specimen Configurations—Typical configurations for
lag at the crosshead rate used. Inertia lag may not exceed 1%
the flat and curved specimens are shown in Figs. 1-4. For
ofthemeasuredload.Theaccuracyofthetestingmachineshall
specimen thicknesses other than those shown, the following
be verified in accordance with Practices E4.
geometries are recommended:
7.2 Loading Nose and Supports, as shown in Figs. 5 and 6,
Specimen length = thickness × 6; Specimen width, b =
shall be 6.00 6 0.50 mm [0.250 6 0.020 in.] and 3.00 6 0.40
thickness × 2.0
mm [0.125 6 0.010 in.] diameter cylinders, respectively, with
a hardness of 60 to 62 HRC, as specified inTest Methods E18, NOTE 2—A discussion of width-to-thickness effects is available in
Adams and Lewis (6).
and shall have finely ground surfaces free of indentation and
burrs with all sharp edges relieved. The loading configuration 8.2.2.1 For curved beam specimens, it is recommended that
shown in Fig. 5 is recommended for curved specimens with a the arc should not exceed 30°. Also, for these specimens, the
radius r to specimen thickness h ratio of r/h of 5 or less. The specimen length is defined as the minimum chord length.
loading configuration shown in Fig. 6 is recommended for flat
8.3 Specimen Preparation—Guide D5687/D5687M pro-
specimens as well as curved specimens with a r/h ratio of
videsrecommendedspecimenpreparationpracticesandshould
greater than 5.
be followed where practical.
7.3 Micrometers and Calipers—A micrometer witha4to 8.3.1 Laminate Fabrication—Laminates may be hand-laid,
8mm[0.16to0.32in.]nominaldiameterballinterfaceoraflat filament-wound or tow-placed, and molded by any suitable
anvil interface shall be used to measure the specimen thick- laminating means, such as press, bag, autoclave, or resin
ness. A ball interface is recommended for thickness measure- transfer molding.
ments when at least one surface is irregular (for example, a 8.3.2 Machining Methods—Specimen preparation is impor-
coarse peel ply surface which is neither smooth nor flat). A tant for these specimens. Take precautions when cutting
micrometer or caliper with a flat anvil interface shall be used specimensfromtheringsorplatestoavoidnotches,undercuts,
D2344/D2344M − 22
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASM B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –A–.
FIG. 3 Curved Specimen Configuration (SI)
rough or uneven surfaces, or delaminations as a result of matrix burn-off technique of Test Method D2584. The void
inappropriate machining methods. Obtain final dimensions by
content equations of Test Methods D2734 are applicable to
water-lubricated precision sawing, milling, or grinding. The both Test Method D2584 and the matrix digestion procedures.
use of diamond tooling has been found to be extremely
8.3.4 Labeling—Label the specimens so that they will be
effective for many material systems. Edges should be flat and
distinctfromeachotherandtraceablebacktotherawmaterial,
parallel within the specified tolerances.
inamannerthatwillbothbeunaffectedbythetestmethodand
8.3.3 If specific gravity, density, reinforcement volume, or
not influence the test method.
voidvolumearetobereported,thenobtainthesesamplesfrom
the same panels being tested. Specific gravity and density may
9. Calibration
be evaluated by means ofTest Methods D792.Volume percent
of the constituents may be evaluated by one of the matrix 9.1 The accuracy of all measuring equipment shall have
digestion procedures of Test Methods D3171 or, for certain certified calibrations that are current at the time of use of the
reinforcement materials such as glass and ceramics, by the equipment.
D2344/D2344M − 22
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASME B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –A–.
FIG. 4 Curved Specimen Configuration (Inch Pound)
10. Conditioning 10.3 If no explicit conditioning process is performed, the
specimen conditioning process shall be reported as “uncondi-
10.1 The recommended pre-test condition is effective mois-
tioned” and the moisture content as “unknown.”
ture equilibrium at a specific relative humidity as established
byTestMethodD5229/D5229M;however,ifthetestrequestor
11. Procedure
doesnotexplicitlyspecifyapre-testconditioningenvironment,
11.1 Parameters to Be Specified Before Test:
no conditioning is required, and the test specimens may be
11.1.1 The specimen sampling method and coupon geom-
tested as prepared.
etry.
10.2 The pre-test specimen conditioning process, to include
11.1.2 The material properties and data-reporting format
specifiedenvironmentalexposurelevelsandresultingmoisture
desired.
content, shall be reported with the test data.
NOTE 4—Determine specific material property, accuracy, and data-
NOTE 3—The term moisture, as used in Test Method D5229/D5229M, reporting requirements before test for proper selection of instrumentation
includes not only the vapor of a liquid and its condensate, but the liquid and data-recording equipment. Estimate operating stress levels to aid in
itself in large quantities, as for immersion. calibration of equipment and determination of equipment settings.
D2344/D2344M − 22
FIG. 5 Curved Laminate Load Diagram
FIG. 6 Flat Laminate Load Diagram
NOTE 5—The test requester may request that additional measurements
11.1.3 The environmental conditioning test parameters.
be performed after the machined specimens have gone through any
11.1.4 If performed, the sampling test method, coupon
conditionin
...

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: D2344/D2344M − 16 D2344/D2344M − 22
Standard Test Method for
Short-Beam Strength of Polymer Matrix Composite Materials
and Their Laminates
This standard is issued under the fixed designation D2344/D2344M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method determines the short-beam strength of high-modulus fiber-reinforced composite materials. The specimen is
a short beam machined from a curved or a flat laminate up to 6.00 mm [0.25 in.] thick. The beam is loaded in three-point bending.
1.2 Application of this test method is limited to continuous- or discontinuous-fiber-reinforced polymer matrix composites, for
which the elastic properties are balanced and symmetric with respect to the longitudinal axis of the beam.
1.3 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in
each system mayare not benecessarily exact equivalents; therefore, to ensure conformance with the standard, each system
mustshall be used independently of the other. Combiningother, and values from the two systems may result in nonconformance
with the standard.shall not be combined.
1.3.1 Within the text, the inch-pound units are shown in brackets.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 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:
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D2584 Test Method for Ignition Loss of Cured Reinforced Resins
D2734 Test Methods for Void Content of Reinforced Plastics
D3171 Test Methods for Constituent Content of Composite Materials
D3878 Terminology for Composite Materials
This test method 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 July 1, 2016July 15, 2022. Published July 2016August 2022. Originally approved in 1965. Last previous edition approved in 20132016 as
D2344 – 13.D2344/D2344M – 16. DOI: 10.1520/D2344_D2344M-16.10.1520/D2344_D2344M-22.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2344/D2344M − 22
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
D5687/D5687M Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
E4 Practices for Force Calibration and Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E18 Test Methods for Rockwell Hardness of Metallic Materials
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics
E1309E691 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in DatabasesPractice for
Conducting an Interlaboratory Study to Determine the Precision of a Test Method (Withdrawn 2015)
E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)
E1471 Guide for Identification of Fibers, Fillers, and Core Materials in Computerized Material Property Databases (Withdrawn
2015)
3. Terminology
3.1 Definitions—Terminology D3878 defines the 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 and Practice
E177 define terms relating to statistics. In the event of a conflict between definitions, Terminology D3878 shall have precedence
over the other documents.
NOTE 1—If the term represents a physical quantity, its analytical dimensions are stated immediately following the term (or letter symbol) in fundamental
dimension form, using the following ASTM standard symbology for fundamental dimensions, shown within square brackets: [M] for mass, [L] for length,
[T] for time, [Θ] for thermodynamic temperature, and [ nd] for nondimensional quantities. Use of these symbols is restricted to analytical dimensions
when used with square brackets, as the symbols may have other definitions when used without the brackets.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 balanced laminate, n—a continuous fiber-reinforced laminate in which each +θ lamina, measured with respect to the
laminate reference axis, is balanced by a –θ lamina of the same material (for example, [0/+45/–45/+45/–45/0]).
3.2.1 short-beam strength, n—the shear stress as calculated in Eq 1, developed at the specimen mid-plane at the failure event
specified in 11.6.
3.2.1.1 Discussion—
Although shear is the dominant applied loading in this test method, the internal stresses are complex, and a variety of failure modes
can occur. Elasticity solutions by Berg et al (1) , Whitney (2), and Sullivan and Van Oene (3) have all demonstrated inadequacies
in classical beam theory in defining the stress state in the short-beam configuration. These solutions show that the parabolic
shear-stress distribution as predicted by Eq 1 only occurs, and then not exactly, on planes midway between the loading nose and
support points. Away from these planes, the stress distributions become skewed, with peak stresses occurring near the loading nose
and support points. Of particular significance is the stress state local to the loading nose in which the severe shear-stress
concentration combined with transverse and in-plane compressive stresses has been shown to initiate failure. However, for the
more ductile matrices, plastic yielding may alleviate the situation under the loading nose (1) and allow other failure modes to occur
such as bottom surface fiber tension (2). Consequently, unless mid-plane interlaminar failure has been clearly observed, the
short-beam strength determined from this test method cannot be attributed to a shear property, and the use of Eq 1 will not yield
an accurate value for shear strength.
3.2.3 symmetric laminate, n—a continuous fiber-reinforced laminate in which each ply above the mid-plane is identically matched
(in terms of position, orientation, and mechanical properties) with one below the mid-plane.
3.3 Symbols:
b b—specimen width.width
CV—sample coefficient of variation (in percent).percent)
sbs
F —short-beam strength.strength
h—specimen thickness.thickness
The last approved version of this historical standard is referenced on www.astm.org.
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n—number of specimens.specimens
P —maximum load observed during the test.test
m
x —measured or derived property for an individual specimen from the sample population.population
i
x¯—sample mean (average).(average)
4. Summary of Test Method
4.1 The short-beam test specimens (Figs. 1-4) are center-loaded as shown in Figs. 5 and 6. The specimen ends rest on two supports
that allow lateral motion, the load being applied by means of a loading nose directly centered on the midpoint of the test specimen.
5. Significance and Use
5.1 In most cases, because of the complexity of internal stresses and the variety of failure modes that can occur in this specimen,
it is not generally possible to relate the short-beam strength to any one material property. However, failures are normally dominated
by resin and interlaminar properties, and the test results have been found to be repeatable for a given specimen geometry, material
system, and stacking sequence (4).
5.2 Short-beam strength determined by this test method can be used for quality control and process specification purposes. It can
also be used for comparative testing of composite materials, provided that failures occur consistently in the same mode (5).
5.3 This test method is not limited to specimens within the range specified in Section 8, but is limited to the use of a loading span
length-to-specimen thickness ratio of 4.0 and a minimum specimen thickness of 2.0 mm [0.08 in.].
6. Interferences
6.1 Accurate reporting of observed failure modes is essential for meaningful data interpretation, in particular, the detection of
initial damage modes.
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASM B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –B–.
FIG. 1 Flat Specimen Configuration (SI)
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NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASME B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –B–.
FIG. 2 Flat Specimen Configuration (Inch Pound)
7. Apparatus
7.1 Testing Machine, properly calibrated, which can be operated at a constant rate of crosshead motion, and which the error in the
loading system shall not exceed 61 %. The load-indicating mechanism shall be essentially free of inertia lag at the crosshead rate
used. Inertia lag may not exceed 1 % of the measured load. The accuracy of the testing machine shall be verified in accordance
with Practices E4.
7.2 Loading Nose and Supports, as shown in Figs. 5 and 6, shall be 6.00 6 0.50 mm [0.250 6 0.020 in.] and 3.00 6 0.40 mm
[0.125 6 0.010 in.] diameter cylinders, respectively, with a hardness of 60 to 62 HRC, as specified in Test Methods E18, and shall
have finely ground surfaces free of indentation and burrs with all sharp edges relieved. The loading configuration shown in Fig.
5 is recommended for curved specimens with a radius r to specimen thickness h ratio of r/h of 5 or less. The loading configuration
shown in Fig. 6 is recommended for flat specimens as well as curved specimens with a r/h ratio of greater than 5.
7.3 Micrometers and Calipers—A micrometer with a 4 to 7 mm8 mm [0.16 to 0.280.32 in.] nominal diameter ball interface or a
flat anvil interface shall be used to measure the specimen width and thickness. A ball interface is recommended for thickness
measurements when at least one surface is irregular (e.g. (for example, a coarse peel ply surface which is neither smooth nor flat).
A micrometer or caliper with a flat anvil interface shall be used for measuring width and length. The use of alternative measurement
devices is permitted if specified (or agreed to) by the test requestor and reported by the testing laboratory. The accuracy of the
instrument(s) shall be suitable for reading within 1 % of the specimen dimensions. For typical specimen geometries, an instrument
with an accuracy of 60 .0025 60.0025 mm [60.0001 in.] is adequate for width and thickness measurements, while an instrument
with an accuracy of 60.025 mm [60.001 in.] is adequate for measurement of width and length.
7.4 Conditioning Chamber, Chamber—whenWhen conditioning materials at nonlaboratory environments, a temperature/vapor-
level-controlled environmental conditioning chamber is required that shall be capable of maintaining the required temperature to
within 63°C (65°F)63 °C (65 °F) and the required vapor level to within 63 %. Chamber conditions shall be monitored either
on an automated continuous basis or on a manual basis at regular intervals.
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NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASM B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –A–.
FIG. 3 Curved Specimen Configuration (SI)
7.5 Environmental Test Chamber, Chamber—anAn environmental test chamber is required for test environments other than
ambient testing laboratory conditions. This chamber shall be capable of maintaining the test specimen at the required test
environment during the mechanical test method.
8. Sampling and Test Specimens
8.1 Sampling—Test at least five specimens per test condition unless valid results can be gained through the use of fewer specimens,
as in the case of a designed experiment. For statistically significant data, consult the procedures outlined in Practice E122. Report
the method of sampling.
8.2 Geometry:
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NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASME B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –A–.
FIG. 4 Curved Specimen Configuration (Inch Pound)
8.2.1 Laminate Configurations—Both multidirectional and pure unidirectional laminates can be tested, provided that there are at
least 10 % 0° fibers in the span direction of the beam (preferably well distributed through the thickness), and that the laminates
are both balanced and symmetric with respect to the span direction of the beam.
8.2.2 Specimen Configurations—Typical configurations for the flat and curved specimens are shown in Figs. 1-4. For specimen
thicknesses other than those shown, the following geometries are recommended:
Specimen length = thickness × 66;
Specimen width, b = thickness × 2.0
NOTE 2—A discussion of width-to-thickness effects is available in Adams and Lewis (6).
8.2.2.1 For curved beam specimens, it is recommended that the arc should not exceed 30°. Also, for these specimens, the specimen
length is defined as the minimum chord length.
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FIG. 5 Horizontal ShearCurved Laminate Load Diagram (Curved Beam)
FIG. 6 Horizontal ShearFlat Laminate Load Diagram (Flat Laminate)
8.3 Specimen Preparation—Guide D5687/D5687M provides recommended specimen preparation practices and should be
followed where practical.
8.3.1 Laminate Fabrication—Laminates may be hand-laid, filament-wound or tow-placed, and molded by any suitable laminating
means, such as press, bag, autoclave, or resin transfer molding.
8.3.2 Machining Methods—Specimen preparation is important for these specimens. Take precautions when cutting specimens
from the rings or plates to avoid notches, undercuts, rough or uneven surfaces, or delaminations as a result of inappropriate
machining methods. Obtain final dimensions by water-lubricated precision sawing, milling, or grinding. The use of diamond
tooling has been found to be extremely effective for many material systems. Edges should be flat and parallel within the specified
tolerances.
8.3.3 If specific gravity, density, reinforcement volume, or void volume are to be reported, then obtain these samples from the same
panels being tested. Specific gravity and density may be evaluated by means of Test Methods D792. Volume percent of the
constituents may be evaluated by one of the matrix digestion procedures of Test Methods D3171 or, for certain reinforcement
D2344/D2344M − 22
materials such as glass and ceramics, by the matrix burn-off technique of Test Method D2584. The void content equations of Test
Methods D2734 are applicable to both Test Method D2584 and the matrix digestion procedures.
8.3.4 Labeling—Label the specimens so that they will be distinct from each other and traceable back to the raw material, in a
manner that will both be unaffected by the test method and not influence the test method.
9. Calibration
9.1 The accuracy of all measuring equipment shall have certified calibrations that are current at the time of use of the equipment.
10. Conditioning
10.1 Standard Conditioning Procedure—Unless a different environment is specified as part of the test method, condition the test
specimens in accordance with Procedure C of The recommended pre-test condition is effective moisture equilibrium at a specific
relative humidity as established by Test Method D5229/D5229M, and store and test at standard laboratory atmosphere (23 6 3°C
(73 6 5°F) and 50 6 10 % relative humidity).; 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 prepared.
10.2 The pre-test specimen conditioning process, to include specified environmental exposure levels and resulting moisture
content, shall be reported with the test data.
NOTE 3—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.
10.3 If no explicit conditioning process is performed, the specimen conditioning process shall be reported as “unconditioned” and
the moisture content as “unknown.”
11. Procedure
11.1 Parameters to Be Specified Before Test:
11.1.1 The specimen sampling method and coupon geometry.
11.1.2 The material properties and data-reporting format desired.
NOTE 4—Determine specific material property, accuracy, and data-reporting requirements before test for proper selection of instrumentation and
data-recording equipment. Estimate operating stress levels to aid in calibration of equipment and determination of equipment settings.
11.1.3 The environ
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