ASTM D5379/D5379M-19e1

Standard Test Method for Shear Properties of Composite Materials by the V-Notched Beam Method

SIGNIFICANCE AND USE
5.1 This test method is designed to produce shear property data for material specifications, research and development, quality assurance, and structural design and analysis. Either in-plane or interlaminar shear properties may be evaluated, depending upon the orientation of the material coordinate system relative to the loading axis. Factors that influence the shear response and should therefore be reported include the following: material, methods of material preparation and lay-up, specimen stacking sequence, specimen preparation, specimen conditioning, environment of testing, specimen alignment and gripping, speed of testing, time at temperature, void content, and volume percent reinforcement.  
5.2 In anisotropic materials, properties may be obtained in any of the six possible shear planes by orienting the testing plane of the specimen with the desired material plane (1-2 or 2-1, 1-3 or 3-1, 2-3  or 3-2). Only a single shear plane may be evaluated for any given specimen. Properties, in the test direction, which may be obtained from this test method, include the following:  
5.2.1 Shear stress/strain response,  
5.2.2 Ultimate strength,  
5.2.3 Ultimate strain, and  
5.2.4 Shear chord modulus of elasticity.
SCOPE
1.1 This test method covers the shear properties of composite materials reinforced by high-modulus fibers. The composite materials are limited to continuous-fiber or discontinuous-fiber-reinforced composites in the following material forms:  
1.1.1 Laminates composed only of unidirectional fibrous laminae, with the fiber direction oriented either parallel or perpendicular to the loading axis.  
1.1.2 Laminates composed only of woven fabric filamentary laminae with the warp direction oriented either parallel or perpendicular to the loading axis.  
1.1.3 Laminates composed only of unidirectional fibrous laminae, containing equal numbers of plies oriented at 0 and 90° in a balanced and symmetric stacking sequence, with the 0° direction oriented either parallel or perpendicular to the loading axis.  
1.1.4 Short-fiber-reinforced composites with a majority of the fibers being randomly distributed.  
Note 1: This shear test concept was originally developed without reference to fiber direction for use on isotropic materials such as metals or ceramics.  
1.2 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.  
1.2.1 Within the text, the inch-pound units are shown in brackets.  
1.3 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.  
1.4 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-Oct-2019
• 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 E1237-20 - Standard Guide for Installing Bonded Resistance Strain Gages
• Effective Date: 15-Aug-2020
• Refers: ASTM E251-20a - Standard Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
• Effective Date: 01-Jun-2020
• Refers: ASTM E251-20 - Standard Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
• Effective Date: 01-May-2020
• 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 D3878-19 - Standard Terminology for Composite Materials
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• 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

Overview

ASTM D5379/D5379M-19e1 is an international standard developed by ASTM for measuring the shear properties of composite materials using the V-notched beam method. This test method is essential for generating accurate and consistent data on the in-plane and interlaminar shear response of composite laminates reinforced with high-modulus fibers. The V-notched beam approach is particularly suitable for continuous-fiber or discontinuous-fiber reinforced composites in various forms, including unidirectional, woven, and short-fiber composites. The standard is commonly used for material specification, research and development, quality assurance, and the structural analysis and design of advanced composite materials.

Key Topics

• Shear Testing of Composites: The V-notched beam test is designed to produce reliable data on shear properties such as ultimate shear strength, shear stress/strain response, ultimate strain, and the shear chord modulus of elasticity.
• Specimen Orientation and Shear Planes: The method enables testing of anisotropic materials across any of six shear planes by aligning the specimen’s material coordinate system relative to the loading axis.
• Material Types Covered:
  • Unidirectional laminates (fibers parallel or perpendicular to loading)
  • Woven fabric laminates (warp direction parallel or perpendicular)
  • Balanced and symmetric [0/90] laminates
  • Short-fiber reinforced composites with randomly distributed fibers
• Influencing Factors: Accurate reporting should include details about material type, preparation, stacking sequence, conditioning, environmental test conditions, specimen alignment and gripping, test speed, and reinforcement volume percent.

Applications

The V-notched beam method for measuring shear properties has wide applicability in multiple sectors, including:

• Aerospace Engineering: Ensures reliable design data for composite structures subjected to shear, such as aircraft skins and internal stiffeners.
• Automotive Industry: Critical for lightweight composite components that must withstand shear forces, improving performance and durability.
• Construction and Civil Engineering: Validates the structural integrity of composite reinforcements in bridges, buildings, and infrastructure.
• Research and Development: Facilitates comparative analysis of new composite formulations, manufacturing processes, and quality assurance protocols.
• Material Specifications and Compliance: Provides basis for certifying composites to customer or regulatory requirements.

The standard can be used to validate both production lots and developmental materials, making it a key part of the composite qualification process.

Related Standards

ASTM D5379/D5379M-19e1 references and works in conjunction with several other ASTM standards and international documents related to composite materials and mechanical testing, including:

• ASTM D792: Test Methods for Density and Specific Gravity of Plastics by Displacement
• ASTM D883: Terminology Relating to Plastics
• ASTM D3171: Test Methods for Constituent Content of Composite Materials
• ASTM D2584 and D2734: Methods for matrix burn-off and void content determination
• ASTM E4: Practices for Force Verification of Testing Machines
• ASTM D5229/D5229M: Methods for Moisture Absorption of Polymer Matrix Composites
• ANSI Y14.5M: Geometric Dimensioning and Tolerancing (for specimen preparation)

These supporting standards help ensure consistency, accuracy, and traceability of mechanical property assessments.

---

By following ASTM D5379/D5379M-19e1, organizations can generate meaningful and traceable shear property data for composite materials, supporting the design, qualification, and ongoing improvement of high-performance composite structures. Adhering to this standard supports compliance with global best practices for material characterization and testing.

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.
´1
Designation: D5379/D5379M − 19
Standard Test Method for
Shear Properties of Composite Materials by the V-Notched
Beam Method
This standard is issued under the fixed designation D5379/D5379M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial corrections were made to the adjunct information in March 2021.
1. Scope 1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method covers the shear properties of compos-
ization established in the Decision on Principles for the
itematerialsreinforcedbyhigh-modulusfibers.Thecomposite
Development of International Standards, Guides and Recom-
materials are limited to continuous-fiber or discontinuous-
mendations issued by the World Trade Organization Technical
fiber-reinforced composites in the following material forms:
Barriers to Trade (TBT) Committee.
1.1.1 Laminates composed only of unidirectional fibrous
laminae, with the fiber direction oriented either parallel or
2. Referenced Documents
perpendicular to the loading axis.
2.1 ASTM Standards:
1.1.2 Laminatescomposedonlyofwovenfabricfilamentary
D792Test Methods for Density and Specific Gravity (Rela-
laminae with the warp direction oriented either parallel or
tive Density) of Plastics by Displacement
perpendicular to the loading axis.
D883Terminology Relating to Plastics
1.1.3 Laminates composed only of unidirectional fibrous
D2584Test Method for Ignition Loss of Cured Reinforced
laminae, containing equal numbers of plies oriented at 0 and
Resins
90°inabalancedandsymmetricstackingsequence,withthe0°
D2734TestMethodsforVoidContentofReinforcedPlastics
directionorientedeitherparallelorperpendiculartotheloading
D3171Test Methods for Constituent Content of Composite
axis.
Materials
1.1.4 Short-fiber-reinforced composites with a majority of
D3878Terminology for Composite Materials
the fibers being randomly distributed.
D5229/D5229MTestMethodforMoistureAbsorptionProp-
NOTE 1—This shear test concept was originally developed without
erties and Equilibrium Conditioning of Polymer Matrix
referencetofiberdirectionforuseonisotropicmaterialssuchasmetalsor
Composite Materials
ceramics.
E4Practices for Force Verification of Testing Machines
1.2 The values stated in either SI units or inch-pound units
E6Terminology Relating to Methods of MechanicalTesting
are to be regarded separately as standard. The values stated in
E111Test Method for Young’s Modulus, Tangent Modulus,
eachsystemarenotnecessarilyexactequivalents;therefore,to
and Chord Modulus
ensure conformance with the standard, each system shall be
E122PracticeforCalculatingSampleSizetoEstimate,With
used independently of the other, and values from the two
Specified Precision, the Average for a Characteristic of a
systems shall not be combined.
Lot or Process
1.2.1 Within the text, the inch-pound units are shown in
E177Practice for Use of the Terms Precision and Bias in
brackets.
ASTM Test Methods
1.3 This standard does not purport to address all of the
E251Test Methods for Performance Characteristics of Me-
safety concerns, if any, associated with its use. It is the
tallic Bonded Resistance Strain Gages
responsibility of the user of this standard to establish appro-
E456Terminology Relating to Quality and Statistics
priate safety, health, and environmental practices and deter-
E1237Guide for Installing Bonded Resistance Strain Gages
mine the applicability of regulatory limitations prior to use.
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 Oct. 15, 2019. Published October 2019. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1993. Last previous edition approved in 2012 as D5379/D5379M–12. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5379_D5379M-19E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D5379/D5379M − 19
2.2 Other Documents: 3.2.4 nominal value, n—a value, existing in name only,
ANSI Y14.5M-1982 Geometric Dimensioning and Toler- assigned to a measurable property for the purpose of conve-
ancing nient designation. Tolerances may be applied to a nominal
ANSI/ASME B 46.1-1985 Surface Texture (Surface value to define an acceptable range for the property.
Roughness, Waviness, and Lay)
3.2.5 shear strength, n—the shear stress carried by a mate-
rial at failure under a pure shear condition.
2.3 ASTM Adjuncts:
V-Notched Beam Shear Fixture Machining Drawings
3.2.5.1 Discussion—Therearenostandardtestmethodsthat
arecapableofproducingaperfectlypureshearstresscondition
3. Terminology
to failure for every material, although some test methods can
come acceptably close for a specific material for a given
3.1 Definitions—Terminology D3878 defines terms relating
engineering purpose.
to high-modulus fibers and their composites. Terminology
D883definestermsrelatingtoplastics.TerminologyE6defines
3.3 Symbols:
terms relating to mechanical testing. Terminology E456 and
3.3.1 A—minimum cross-sectional area of a coupon.
Practice E177 define terms relating to statistics. In the event of
3.3.2 CV—coefficient of variation statistic of a sample
a conflict between terms, Terminology D3878 shall have
population for a given property (in percent).
precedence over the other standards.
su
3.2 Definitions of Terms Specific to This Standard:
3.3.3 F —ultimate shear strength in the test direction.
u
NOTE 2—If the term represents a physical quantity, its analytical
3.3.4 F —ultimate strength in the test direction.
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
3.3.5 F° (offset)—the value of the shear stress at the inter-
fundamental dimension form, using the following ASTM standard sym-
section of the shear chord modulus of elasticity and the stress
bology for fundamental dimensions, shown within square brackets: [M]
formass,[L]forlength,[T]fortime,[Θ]forthermodynamictemperature,
strain curve when the modulus is offset along the engineering
and[nd]fornondimensionalquantities.Useofthesesymbolsisrestricted
shear strain axis from the origin by the reported strain offset
to analytical dimensions when used with square brackets, as the symbols
value.
may have other definitions when used without the brackets.
3.3.6 G—shear modulus of elasticity in the test direction.
3.2.1 in-plane shear, n—any of the shear properties describ-
ing the response resulting from a shear force or deformation
3.3.7 h—coupon thickness.
appliedtothe1-2materialplane.(Seealsomaterialcoordinate
3.3.8 n—number of coupons per sample population.
system.)
3.3.9 P—force carried by test coupon.
3.2.2 interlaminar shear, n—any of the shear properties
describing the response resulting from a shear force or defor- f
3.3.10 P—force carried by test coupon at failure.
mation applied to the 1-3 or 2-3 material planes. (See also
max
3.3.11 P —maximum force carried by test coupon before
material coordinate system.)
failure.
3.2.3 material coordinate system, n—a Cartesian coordinate
system describing the principal material coordinate system,
3.3.12 s —standard deviation statistic of a sample popu-
n−1
using 1, 2, and 3 for the axes, as shown in Fig. 1.
lation for a given property.
3.3.13 w—coupon width.
3.3.14 x—test result for an individual coupon from the
i
sample population for a given property.
3.3.15 x¯—mean or average (estimate of mean) of a sample
population for a given property.
3.3.16 γ—engineering shear strain.
3.3.17 ε—general symbol for strain, whether normal strain
or shear strain.
3.3.18 ε—indicated normal strain from strain transducer or
extensometer.
3.3.19 σ—normal stress.
3.3.20 τ—shear stress.
3.3.21 θ—ply orientation angle.
FIG. 1 Material Coordinate System
4. Summary of Test Method
4.1 Amaterial coupon in the form of a rectangular flat strip
withsymmetricalcentrallylocated v-notches,shownschemati-
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
cally in Fig. 2, is loaded in a mechanical testing machine by a
4th Floor, New York, NY 10036.
special fixture (shown schematically in Fig. 3 and in more
Available from ASTM International Headquarters, www.astm.org. Order
Adjunct No. ADJD5379-E-PDF. detail in the machining drawings of ASTM Adjunct
´1
D5379/D5379M − 19
force.Therelativedisplacementbetweenthetwofixturehalves
loads the notched specimen. By placing two strain gage
elements,orientedat 645°totheloadingaxis,inthemiddleof
the specimen (away from the notches) and along the loading
axis, the shear response of the material can be measured.
4.3 The loading can be idealized as asymmetric flexure, as
shown by the shear and bending moment diagrams of Fig. 4.
The notches influence the shear strain along the loading
direction, making the distribution more uniform than would be
seen without the notches. While the degree of uniformity is a
function of material orthotropy, the best overall results, when
testing in the 1-2 plane, have been obtained on [0/90] -type
ns
laminates.
Nominal Specimen Dimensions
d = 19mm[0.75in.]
d = 3.8 mm [0.15 in.]
h = as required
L = 76 mm [3.0 in.]
While the idealization indicates constant shear loading and zero bending
r = 1.3 mm [0.05 in.]
moments in the specimen at the notches, the actual load application is distributed
w = 11.4 mm [0.45 in.]
and imperfect, which contributes to asymmetry in the shear strain distribution and
to a component of normal stress that is particularly deleterious to [90] specimens
n
(16).
FIG. 2 V-Notched Beam Test Coupon Schematic
FIG. 3 V-Notched Beam Test Fixture Schematic
ADJD5379-E-PDF.
4.2 The specimen is inserted into the fixture with the notch
located along the line of action of loading by means of an
alignmenttoolthatreferencesthefixture.Thetwohalvesofthe
fixture are compressed by a testing machine while monitoring
The specimen and fixture are based upon work at the University of Wyoming
CompositeMaterialsResearchGroup (1, 2),andweresubsequentlymodifiedbythe
group (3, 4) into the configuration used by this test method. The Wyoming
investigations referred to the earlier work ofArcan (5-7) and Iosipescu (8-10), and
the later work of a number of other researchers, including Refs (11-16) (early
NOTE 1—The value of the dimension b is not critical to the concept.
historical perspectives are given in Refs (1, 17)). The boldface numbers in
parentheses refer to the list of references at the end of this standard. FIG. 4 Idealized Force, Shear, and Moment Diagrams
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D5379/D5379M − 19
5. Significance and Use 6.4 Force Eccentricity—Twisting of the specimen during
loading can occur, affecting strength results, and especially,
5.1 This test method is designed to produce shear property
elastic modulus measurement. Twisting may occur due to an
data for material specifications, research and development,
out-of-tolerance fixture, or from specimens that are too thin
quality assurance, and structural design and analysis. Either
(unstable), improperly installed in the fixture, out-of-tolerance
in-plane or interlaminar shear properties may be evaluated,
because of poor specimen preparation, or of a material con-
depending upon the orientation of the material coordinate
figuration with an extremely low tolerance to twist. It is
system relative to the loading axis. Factors that influence the
recommended that at least one specimen of each sample be
shear response and should therefore be reported include the
tested with back-to-back rosettes to evaluate the degree of
following: material, methods of material preparation and lay-
twist. Evaluate the percent twist for the specimen by substitut-
up, specimen stacking sequence, specimen preparation, speci-
ing the shear modulus from each side, G and G , into
a b
men conditioning, environment of testing, specimen alignment
|(G − G )/(G + G )|×100,evaluatedat0.004absolutestrain.
a b a b
and gripping, speed of testing, time at temperature, void
If the amount of twist is greater than 3%, then the specimens
content, and volume percent reinforcement.
should be examined for cause of the twisting, and corrected, if
5.2 In anisotropic materials, properties may be obtained in
possible.Ifnocauseisapparentorcorrectionpossible,andthe
any of the six possible shear planes by orienting the testing
twisting persists, then the shear modulus measurement should
plane of the specimen with the desired material plane (1-2 or
be made using the average response of back-to-back rosettes.
2-1, 1-3 or 3-1, 2-3 or 3-2). Only a single shear plane may be
NOTE 3—Twisting as a result of minor tolerance variations can be
evaluated for any given specimen. Properties, in the test
mitigated by use of a thin compliant interface, such as a plastic-backed
direction, which may be obtained from this test method,
adhesive tape, between the fixture and the load-bearing surface of the
include the following:
specimen.
5.2.1 Shear stress/strain response,
6.5 Specimen Geometry Modifications—Detailed stress
5.2.2 Ultimate strength,
analysisofthev-notchspecimenhasshownthatadjustmentsto
5.2.3 Ultimate strain, and
the notch dimensions (notch angle, depth, and radius) can
5.2.4 Shear chord modulus of elasticity.
minimize non-uniformity in the shear-stress distribution as a
result of material orthotropy. In order to minimize the com-
6. Interferences
plexityofthistestmethod,asinglestandardgeometryhasbeen
adopted. However, variations to the notch angle, depth, and
6.1 MaterialandSpecimenPreparation—Poormaterialfab-
radiusforthepurposeofoptimizingthespecimenperformance
rication practices, lack of control of fiber alignment, and
for a particular material are acceptable when the variations are
damage induced by improper coupon machining are known
clearly noted in the report.
causes of high material data scatter in composites.
6.6 Determination of Failure:
6.2 Materials and Coarse Structure—One of the fundamen-
tal assumptions of this test method is that the material must be
6.6.1 [0] Materials—In [0] specimens tested in the 1-2
n n
relatively homogeneous with respect to the size of the test
plane, a visible crack typically develops at the notch root,
section. Materials that have relatively coarse features with
causing a small drop in force before ultimate failure, as shown
respect to the test section dimensions, such as fabrics using
in Fig. 5. The small force drop accompanying the notch root
large filament count tows (such as tows of 12000 filaments or
crack is not considered the failure force; rather the force that
more) or certain braided structures, should not be tested with
accompanies failure in the test section shall be used as the
this specimen size. Scale-up of the specimen and the fixturing
failure force.
to accommodate such materials is possible, but is beyond the
6.6.2 [90] Materials—In [90] specimens tested in the 2-1
n n
scope of this test method.
plane, the ultimate failure force is clearly defined by the
maximum force attained on the force-deflection curve.
6.3 Elastic Modulus Measurement—The calculations in this
test method assume a uniform shear stress state between the 6.6.3 [0/90] , SMC, Toughened Materials—For [0/90] ,
ns ns
notches. The actual degree of uniformity varies with the level SMC, or toughened materials, the shear failure force may be
of material orthotropy and the direction of loading. Both lower than the maximum force attainable during the test. In
analysis and full-field experimental strain measurement have such materials, the fibers may reorient following shear failure,
shownthatwhentestinginthe 1-2plane,[0] specimensresult subsequentlyallowingthefiberstocarryamajorportionofthe
n
in an elastic modulus estimate that is too high (about 10% too force. This reorientation is more likely to occur in composites
high for carbon/epoxy), while [90] specimens of the same with tough matrix materials that are very nonlinear in shear or
n
material result in a value that is about 20% too low. The most in laminates containing off-axis fibers. In such cases, the shear
accurate measurements of in-plane shear modulus for unidi- failure force can often be determined by correlating visual
rectional materials have been shown to result from the [0/90] observationoffailureinthetestsectionwithaforcedroporby
ns
specimen. The use of specialized shear strain gages, which asignificantchangeintheslopeoftheforce-displacementplot,
span the length of the test section between the notch roots, as shown in Fig. 5. Additionally, some toughened materials
allows the average shear strain to be measured even with a may deform to such an extent that shear failure does not occur
nonuniform shear stress state present, and thus is recom- at all; rather the specimen ultimately fails in a mixed-mode
mended. failure. Consequently, to avoid the reporting of results that are
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D5379/D5379M − 19
7.4.2 Drive Mechanism—The testing machine drive mecha-
nism shall be capable of imparting to the movable head a
controlled velocity with respect to the stationary head. The
velocity of the movable head shall be capable of being
regulated as specified in 11.3.
7.4.3 Force Indicator—The testing machine force-sensing
device shall be capable of indicating the total force being
carried by the test specimen. This device shall be essentially
free from inertia lag at the specified rate of testing and shall
indicate the force with an accuracy over the force range(s) of
interest of within 61% of the indicated value. The force
range(s) of interest may be fairly low for modulus evaluation,
much higher for strength evaluation, or both, as required.
NOTE4—Obtainingprecisionforcedataoveralargerangeofinterestin
the same test, such as when both elastic modulus and ultimate force are
being determined, places extreme requirements on the load cell and its
calibration. For some equipment, a special calibration may be required.
For some combinations of material and load cell, simultaneous precision
measurement of both elastic modulus and ultimate strength may not be
possible, and measurement of modulus and strength may have to be
performed in separate tests using a different load cell range for each test.
7.4.4 Platens/Adapter—One of the testing machine heads
shall be capable of supporting the lower half of the v-notched
FIG. 5 Typical V-Notched Beam Force-Displacement Plots
beamtestfixture(see7.4.5)andtheotherheadshallbecapable
of being attached to the upper half of the fixture, using an
adapter or platen interface as required. If required, one of the
notrepresentativeofshearstrength,thistestmethodterminates
interfaces may be capable of relieving minor misalignments
data reporting at an engineering shear strain of 5%.
between the heads, such as a hemispherical ball joint.
7. Apparatus
7.4.5 Fixturing—The fixture used shall be a four-point
asymmetric flexure fixture shown schematically in Fig. 3, and
7.1 Micrometers and Calipers—A micrometer witha4to
in more detail in the machining drawings of ASTM Adjunct
8mm[0.16to0.32in.]nominaldiameterball-interfaceoraflat
ADJD5379-E-PDF. Each half of the fixture contains a wedge-
anvil interface shall be used to measure the specimen thick-
action grip which lightly clamps one half of the test specimen
ness. A ball interface is recommended for thickness measure-
across the specimen width and supports the specimen on its
ments when at least one surface is irregular (for example, a
back face. One of the grips, normally the lower half, is
coarse peel ply surface which is neither smooth nor flat). A
mounted on a base plate which also supports a linear bearing
micrometer or caliper with a flat anvil interface shall be used
shaft, while the other grip, normally in the upper position,
for measuring length, shoulder width, and other machined
contains a linear bearing which mounts over the shaft on the
surface dimensions.Ablade micrometer or non-contact device
base. Each element is attached to or supported by one of the
such as an optical comparator shall be used for measuring the
testing machine heads. A 13mm [0.5in.] span is left unsup-
width between notches. The use of alternative measurement
portedbetweenfixturehalves.Analignmenttoolisprovidedto
devices is permitted if specified (or agreed to) by the test
ensurethatthespecimennotchisalignedwiththelineofaction
requestor and reported by the testing laboratory. The accuracy
of the loading fixture.
of the instrument(s) shall be suitable for reading to within 1%
of the specimen dimensions. For typical specimen geometries,
7.5 Strain Indicating Device—Bonded resistance strain
an instrument with an accuracy of 60.0025mm [60.0001in.] gages shall be used to measure strain.Aminimum of two gage
is adequate for thickness measurements, while an instrument
elements is required, centered about the loading axis in the
with an accuracy of 60.025mm [60.001in.] is adequate for gage section of the specimen, as shown in Fig. 6, and mounted
measurement of length, width, and other machined surface
at +45° and −45° to the loading axis. If specimen twisting is a
dimensions. concern, then two gage elements on each side of the specimen
shouldbesimultaneouslymeasuredtoallowforacorrectionas
7.2 Angle Measuring Device, for measuring the specimen
aresultofanytwistingofthespecimen,asdiscussedinSection
notch angle, accurate to within 60.5°.
6. The output from each pair may be monitored individually
7.3 Radius Measuring Device, for measuring the specimen
andtheoutputssummedfollowingthetest,oreachpairmaybe
notch radius, accurate to within 625 µm [60.001 in.].
wired as a half-bridge so that the recorded strain is the sum of
7.4 Testing Machine—The testing machine shall be in con- the absolute value of the response of each gage-yielding the
shear strain response directly.
formance with Practices E4 and shall satisfy the following
requirements:
7.4.1 Testing Machine Heads—The testing machine shall
Available from several commercial test fixture suppliers or testing equipment
have both an essentially stationary head and a movable head. companies.
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D5379/D5379M − 19
difference between the gage temperature compensation factor
and the coefficient of thermal expansion of the coupon mate-
rial.
7.5.1.3 Considerationofsomeformoftemperaturecompen-
sation is recommended, even when testing at standard labora-
tory atmosphere. Temperature compensation is required when
testing in non-ambient temperature environments.
7.5.1.4 Consideration should be given to the transverse
sensitivity of the selected strain gage. The strain gage manu-
facturer should be consulted for recommendations on trans-
verse sensitivity corrections and effects on composites.
7.6 Conditioning Chamber—When conditioning materials
NOTE 1—The active elements of two orthogonal strain gages are
at non-laboratory environments, a temperature-vapor-level-
centeredbetweenthenotchrootsattheangleshown.Theelementsmaybe
controlledenvironmentalconditioningchamberisrequiredthat
independent, or in a stacked or unstacked rosette.
FIG. 6 Strain Gage Locations shall be capable of maintaining the required temperature to
within 63°C[65°F] and the required relative vapor level to
within 63%.Chamberconditionsshallbemonitoredeitheron
7.5.1 Bonded Resistance Strain Gage Selection—Strain
an automated continuous basis or on a manual basis at regular
gage selection is a compromise based on the type of material.
intervals.
The use of specialized shear strain gages, which feature a thin
7.7 Environmental Test Chamber—An environmental test
active gage section that spans the length of the test section
chamber is required for test environments other than ambient
between the notch roots, generally is recommended.
testinglaboratoryconditions.Thischambershallbecapableof
Otherwise, an active gage length of 1.5 mm [0.062 in.] is
maintaining the gage section of the test specimen at the
recommended for most materials, although larger sizes may be
required test environment during the mechanical test.
more suitable for some woven fabrics.The active gage section
area should not be so large as to extend significantly beyond
8 8. Sampling and Test Specimens
the area in which shear strain is relatively uniform. Gage
calibration certification shall comply with Test Methods E251. 8.1 Sampling—Test at least five specimens per test condi-
Strain gages with a minimum normal strain range of approxi-
tions unless valid results can be gained through the use of
mately 3% (yielding 6% engineering shear strain) are recom- fewerspecimens,suchasinthecaseofadesignedexperiment.
mended. When testing woven fabric laminates, gage selection
Forstatisticallysignificantdata,consulttheprocedureoutlined
should consider the use of an active gage length that is at least in Practice E122. Report the method of sampling.
asgreatasthecharacteristicrepeatingunitoftheweave.Some
NOTE 5—If specimens are to undergo environmental conditioning to
guidelines on the use of strain gages on composites follow. A
equilibrium, and are of such type or geometry that the weight change of
general reference on the subject is Tuttle and Brinson (18).
thematerialcannotbeproperlymeasuredbyweighingthespecimenitself
7.5.1.1 Surface preparation of fiber-reinforced composites (suchasatabbedmechanicalcoupon),thenanothertravelercouponofthe
same nominal thickness and appropriate size (but without tabs) shall be
in accordance with Guide E1237 can penetrate the matrix
used to determine when equilibrium has been reached for the specimens
material and cause damage to the reinforcing fibers, resulting
being conditioned.
in improper coupon failures. Reinforcing fibers should not be
exposed or damaged during the surface preparation process. 8.2 Geometry—Thespecialcouponisarectangularflatstrip
with symmetrical centrally located v-notches. The mandatory
The strain gage manufacturer should be consulted regarding
surface preparation guidelines and recommended bonding requirements are described in 8.2.1. Recommendations on
parameters that are not required are discussed in 8.2.2.
agents for composites, pending the development of a set of
standard practices for strain gage installation surface prepara-
8.2.1 Specimen Requirements:
tion of fiber-reinforced composite materials.
8.2.1.1 Shape, Dimensions, Tolerances, and
7.5.1.2 Consideration should be given to the selection of
Configuration—Therequiredspecimenshape,dimensions,and
gages having larger resistances to reduce heating effects on
tolerances are described in Fig. 7 (SI) and Fig. 8 (inch-pound).
low-conductivity materials. Resistances of 350 Ω or higher are
If required, adjust the standard notch angle of 90°, notch depth
preferred.Additional consideration should be given to the use
of20%,andnotchradiusof1.3mm[0.050in.]tomeetspecial
of the minimum possible gage excitation voltage consistent
material requirements, but any deviation from these values
withthedesiredaccuracy(1to2Visrecommended)toreduce
must be recorded with the test results, and the standard
the power consumed further by the gage. Heating of the
tolerances on these features still apply.As discussed in Section
couponbythegagemay affect the performance of thematerial
6and15.1,whentestinglaminatedmaterialsinthe1-2material
directly or it may affect the indicated strain as a result of a
plane, the [0/90] specimen has been found to provide a more
ns
accurate modulus determination, shows less variation in the
strength results, and is generally preferred over either the [0]
n
A typical gage would have a 0.062 to 0.125in. active gage length, 350 Ω
or [90] specimens.
n
resistance, a strain rating of 3% or better, and the appropriate environmental
resistance and thermal coefficient. 8.2.2 Specific Recommendations:
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D5379/D5379M − 19
NOTE 1—Interpret Fig. 8 in accordance with ANSI Y14.5M-1982,
subject to the following:
NOTE 1—Interpret Fig. 7 in accordance with ANSI Y14.5M-1982,
(1) All dimensions in inches with decimal tolerances as follows:
subject to the following:
0.X 0.XX 0.XXX
(1) All dimensions in millimetres with decimal tolerances as follows:
6 0.1 60.03 60.010
No decimal 0.X 0.XX
(2) All angles have a tolerance of 60.5°.
62.5 60.75 60.25
(3) Ply orientation direction tolerance relative to−A− (or to−B−)
(2) All angles have a tolerance of 60.5°.
within 60.5°.
(3) Ply orientation direction tolerance relative to−A− (or to−B−)
(4) Finishonmachinededgesnottoexceed64 √.FinishonV-notchnot
within 60.5°
to exceed 32 √ (symbology is in accordance with ANSI/ASME B46.1-
(4) Finish on machined edges not to exceed 1.6 √. Finish on V-notch
1985, with roughness height in microinches).
not to exceed 0.8 √ (symbology is in accordance with ANSI/ASME
(5) Values to be provided for the following, subject to any ranges
B46.1-1985, with roughness height in micrometres.)
shownonthefieldofFig.8:material,lay-up,andplyorientationreference
(5) Values to be provided for the following, subject to any ranges
relative to−A−, coupon thickness, tab material, tab thickness, and tab
showninthefieldofFig.7:material,lay-up,andplyorientationreference
adhesive.
relative to−A−, coupon thickness, tab material, tab thickness, and tab
adhesive. FIG. 8 V-Notched Beam Test Specimen Drawing (Inch Pound)
FIG. 7 V-Notched Beam Test Specimen Drawing (SI)
localcrushingfailuresofthelaminatebythegrippingregionof
8.2.2.1 Specimen/Tab Thickness—A wide range is allowed
the fixture and reduces the possibility of twisting of the
in the requirement for specimen thickness and tab thickness to
specimen in the fixture.
allow the user some flexibility in unusual cases. However, if at
(1) Tab Material—The most consistently used bonded tab
allpossible,thespecimenthicknessshouldbekeptintherange
material has been continuous E-glass fiber-reinforced polymer
from 3 to 4 mm [0.120 to 0.160 in.].Atypical tab thickness is
matrix materials (woven or unwoven) in a [0/90] laminate
ns
1.5 mm [0.062 in.].
configuration.
8.2.2.2 Gripping/Use of Tabs—There are many material
(2) Bonded Tab Adhesive—Use any high-elongation
configurations, such as [0/90] laminates, fabric-based
ns
(tough) adhesive system that meets the environmental require-
materials, or randomly reinforced sheet molding compounds,
ments when bonding tabs to the material under test.Auniform
whichcanbesuccessfullytestedwithouttabs.However,useof
bondline thickness is desirable.
tabs is recommended when testing materials that are less than
2.5 mm [0.100 in.] thick.Tabs, locally bonded to both faces of 8.3 Material Orientation—Perform shear tests in any of the
the specimen away from the test region, strengthen and six material shear planes, as defined by Fig. 1 and by proper
stabilizethespecimenbylocallyincreasingthethicknessinthe orientationofthelaminatewhenfabricatingandmachiningthe
gripping region, as shown in Fig. 7 and Fig. 8.This minimizes coupon as illustrated by Fig. 9.
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D5379/D5379M − 19
ties by cutting coupons from a [0] or [90] laminate that is
n n
prepared as fol
...