ASTM D3039/D3039M-17

Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials

SIGNIFICANCE AND USE
5.1 This test method is designed to produce tensile property data for material specifications, research and development, quality assurance, and structural design and analysis. Factors that influence the tensile 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. Properties, in the test direction, which may be obtained from this test method include the following:  
5.1.1 Ultimate tensile strength,  
5.1.2 Ultimate tensile strain,  
5.1.3 Tensile chord modulus of elasticity,  
5.1.4 Poisson's ratio, and  
5.1.5 Transition strain.
SCOPE
1.1 This test method determines the in-plane tensile properties of polymer matrix composite materials reinforced by high-modulus fibers. The composite material forms are limited to continuous fiber or discontinuous fiber-reinforced composites in which the laminate is balanced and symmetric with respect to the test direction.  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.  
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-2017
• ICS: 49.025.40 - Rubber and plastics
• 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 D3039/D3039M-17 – Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials is a widely recognized standard developed by ASTM International. This test method is essential for determining the in-plane tensile properties of polymer matrix composites reinforced with high-modulus fibers. The standard covers both continuous and discontinuous fiber-reinforced composites, provided the test laminates are balanced and symmetric with respect to the test direction. Widely used in industries such as aerospace, automotive, and construction, ASTM D3039/D3039M-17 provides crucial data to support material specification, quality assurance, research and development, and structural design.

Key Topics

Core Objectives and Test Methodology

• The primary purpose of ASTM D3039/D3039M-17 is to measure the tensile properties-strength, strain, modulus, Poisson’s ratio, and transition strain-of polymer matrix composites.
• The test involves mounting a specimen in the grips of a mechanical testing machine and applying a monotonic tensile load until failure. Measurements such as maximum force, elongation, and strain are used to calculate relevant properties.

Influencing Factors

• Material selection and preparation, lay-up method, and stacking sequence.
• Specimen preparation, conditioning, and alignment during testing.
• Gripping technique, speed of testing, and environmental conditions.
• Void content and reinforcement volume percent, which can significantly affect test results and must be reported.

Tensile Properties Evaluated

• Ultimate Tensile Strength: Maximum stress material can withstand while being stretched.
• Ultimate Tensile Strain: Deformation at the point of breakage.
• Tensile Chord Modulus of Elasticity: Material stiffness under tension.
• Poisson’s Ratio: Ratio of lateral to axial strain.
• Transition Strain: Strain at which there is a significant change in the slope of the stress-strain curve.

Applications

Material Specifications and Development

• ASTM D3039/D3039M-17 is routinely used for qualifying and certifying composite materials for high-performance applications.
• Supports product development by providing reliable data on mechanical properties necessary for material selection.

Structural Design and Analysis

• Structural engineers use tensile property data for analytical modeling, simulation, and safety evaluations of components made from fiber-reinforced polymer composites.
• Vital for standardizing materials used in critical applications, especially in the aerospace, defense, and transportation sectors.

Quality Assurance and Process Control

• Manufacturing facilities leverage this standard for batch validation, ensuring each production run meets rigorous mechanical property requirements.

Research and Benchmarking

• Academic and industrial R&D teams rely on this method for comparative studies, investigating the effects of new fiber types, matrix materials, or fabrication techniques on tensile performance.

Related Standards

ASTM D3039/D3039M-17 references several other ASTM standards for terminology, testing, and material property evaluation, ensuring a robust measurement system. Key related standards include:

• ASTM D792: Density and Specific Gravity of Plastics
• ASTM D2584: Ignition Loss for Cured Reinforced Resins
• ASTM D2734: Void Content of Reinforced Plastics
• ASTM D3171: Constituent Content of Composites
• ASTM D5229/D5229M: Moisture Absorption and Conditioning of Polymer Matrix Composites
• ASTM E4: Force Verification of Testing Machines
• ASTM E83: Extensometer Systems Verification
• ASTM E111: Young’s Modulus and Modulus Measurement
• ASTM E132: Poisson’s Ratio at Room Temperature
• ASTM E1012: Testing Frame and Specimen Alignment

Practical Value

Compliance with ASTM D3039/D3039M-17 ensures consistency, reliability, and repeatability in the measurement of tensile properties for polymer matrix composites. This enables manufacturers, designers, and engineers to make informed, standardized decisions, leading to enhanced product safety, quality control, and innovation in composite material applications. Integrating this standard into testing protocols is essential for organizations aiming to meet global expectations for material performance, especially in demanding, regulated industries.

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: D3039/D3039M − 17
Standard Test Method for
Tensile Properties of Polymer Matrix Composite Materials
This standard is issued under the fixed designation D3039/D3039M; 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 D2734TestMethodsforVoidContentofReinforcedPlastics
D3171Test Methods for Constituent Content of Composite
1.1 This test method determines the in-plane tensile prop-
Materials
erties of polymer matrix composite materials reinforced by
D3878Terminology for Composite Materials
high-modulus fibers.The composite material forms are limited
D5229/D5229MTestMethodforMoistureAbsorptionProp-
to continuous fiber or discontinuous fiber-reinforced compos-
erties and Equilibrium Conditioning of Polymer Matrix
ites in which the laminate is balanced and symmetric with
Composite Materials
respect to the test direction.
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. Within the text, the
E83Practice for Verification and Classification of Exten-
inch-pound units are shown in brackets. The values stated in
someter Systems
each system are not exact equivalents; therefore, each system
E111Test Method for Young’s Modulus, Tangent Modulus,
must be used independently of the other. Combining values
and Chord Modulus
from the two systems may result in nonconformance with the
E122PracticeforCalculatingSampleSizetoEstimate,With
standard.
Specified Precision, the Average for a Characteristic of a
1.3 This standard does not purport to address all of the Lot or Process
safety concerns, if any, associated with its use. It is the
E132Test Method for Poisson’s Ratio at RoomTemperature
responsibility of the user of this standard to establish appro- E177Practice for Use of the Terms Precision and Bias in
priate safety, health, and environmental practices and deter-
ASTM Test Methods
mine the applicability of regulatory limitations prior to use. E251Test Methods for Performance Characteristics of Me-
1.4 This international standard was developed in accor-
tallic Bonded Resistance Strain Gages
dance with internationally recognized principles on standard-
E456Terminology Relating to Quality and Statistics
ization established in the Decision on Principles for the E1012Practice for Verification of Testing Frame and Speci-
Development of International Standards, Guides and Recom-
men Alignment Under Tensile and Compressive Axial
mendations issued by the World Trade Organization Technical Force Application
Barriers to Trade (TBT) Committee.
E1237Guide for Installing Bonded Resistance Strain Gages
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 Definitions—Terminology D3878 defines terms relating
D792Test Methods for Density and Specific Gravity (Rela-
to high-modulus fibers and their composites. Terminology
tive Density) of Plastics by Displacement
D883definestermsrelatingtoplastics.TerminologyE6defines
D883Terminology Relating to Plastics
terms relating to mechanical testing. Terminology E456 and
D2584Test Method for Ignition Loss of Cured Reinforced
Practice E177 define terms relating to statistics. In the event of
Resins
a conflict between terms, Terminology D3878 shall have
precedence over the other standards.
This test method is under the jurisdiction of ASTM Committee D30 on
Composite Materials and is the direct responsibility of Subcommittee D30.04 on
3.2 Definitions of Terms Specific to This Standard:
Lamina and Laminate Test Methods.
3.2.1 Note—If the term represents a physical quantity, its
Current edition approved Oct. 15, 2017. Published November 2017. Originally
analytical dimensions are stated immediately following the
approved in 1971. Last previous edition approved in 2014 as D3039/D3039M–14.
DOI: 10.1520/D3039_D3039M-17.
term (or letter symbol) in fundamental dimension form, using
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the following ASTM standard symbology for fundamental
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
dimensions, shown within square brackets: [M] for mass, [L]
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. for length, [T] for time, [Θ] for thermodynamic temperature,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3039/D3039M − 17
and [ nd] for nondimensional quantities. Use of these symbols 4. Summary of Test Method
is restricted to analytical dimensions when used with square
4.1 Athinflatstripofmaterialhavingaconstantrectangular
brackets,asthesymbolsmayhaveotherdefinitionswhenused
cross section is mounted in the grips of a mechanical testing
without the brackets.
machine and monotonically loaded in tension while recording
3.2.2 nominal value, n—a value, existing in name only,
the force. The ultimate strength of the material can be
assigned to a measurable property for the purpose of conve-
determined from the maximum force carried before failure. If
nient designation. Tolerances may be applied to a nominal
the coupon strain is monitored with strain or displacement
value to define an acceptable range for the property.
transducers then the stress-strain response of the material can
be determined, from which the ultimate tensile strain, tensile
3.2.3 transition region, n—a strain region of a stress-strain
modulus of elasticity, Poisson’s ratio, and transition strain can
or strain-strain curve over which a significant change in the
be derived.
slope of the curve occurs within a small strain range.
transition
3.2.4 transition strain, ε [nd], n—the strain value at
5. Significance and Use
the mid range of the transition region between the two
5.1 This test method is designed to produce tensile property
essentially linear portions of a bilinear stress-strain or strain-
data for material specifications, research and development,
strain curve.
quality assurance, and structural design and analysis. Factors
3.2.4.1 Discussion—Many filamentary composite materials
that influence the tensile response and should therefore be
show essentially bilinear behavior during force application,
reported include the following: material, methods of material
such as seen in plots of either longitudinal stress versus
preparation and lay-up, specimen stacking sequence, specimen
longitudinal strain or transverse strain versus long longitudinal
preparation, specimen conditioning, environment of testing,
strain. There are varying physical reasons for the existence of
specimen alignment and gripping, speed of testing, time at
a transition region. Common examples include: matrix crack-
temperature, void content, and volume percent reinforcement.
ing under tensile force application and ply delamination.
Properties, in the test direction, which may be obtained from
this test method include the following:
3.3 Symbols:
A—average cross-sectional area of a coupon. 5.1.1 Ultimate tensile strength,
5.1.2 Ultimate tensile strain,
B —percent bending for a uniaxial coupon of rectangular
y
5.1.3 Tensile chord modulus of elasticity,
cross section about y axis of the specimen (about the narrow
5.1.4 Poisson’s ratio, and
direction).
5.1.5 Transition strain.
B —percent bending for a uniaxial coupon of rectangular
z
cross section about z axis of the specimen (about the wide
6. Interferences
direction).
6.1 MaterialandSpecimenPreparation—Poormaterialfab-
CV—coefficient of variation statistic of a sample population
rication practices, lack of control of fiber alignment, and
for a given property (in percent).
damage induced by improper coupon machining are known
E—modulus of elasticity in the test direction.
causes of high material data scatter in composites.
tu
F —ultimate tensile strength in the test direction.
su
6.2 Gripping—A high percentage of grip-induced failures,
F —ultimate shear strength in the test direction.
especiallywhencombinedwithhighmaterialdatascatter,isan
h—coupon thickness.
indicator of specimen gripping problems. Specimen gripping
L —extensometer gage length.
g
methods are discussed further in 7.2.4, 8.2, and 11.5.
L —minimum required bonded tab length.
min
6.3 System Alignment—Excessive bending will cause pre-
n—number of coupons per sample population.
mature failure, as well as highly inaccurate modulus of
P—force carried by test coupon.
f elasticity determination. Every effort should be made to elimi-
P—force carried by test coupon at failure.
nate excess bending from the test system. Bending may occur
max
P —maximumforcecarriedbytestcouponbeforefailure.
asaresultofmisalignedgripsorfromspecimensthemselvesif
s —standard deviation statistic of a sample population for
n−1
improperly installed in the grips or out-of-tolerance caused by
a given property.
poor specimen preparation. If there is any doubt as to the
w—coupon width.
alignment inherent in a given test machine, then the alignment
x—test result for an individual coupon from the sample
i
should be checked as discussed in 7.2.5.
population for a given property.
6.4 Edge Effects inAngle Ply Laminates—Premature failure
x¯—mean or average (estimate of mean) of a sample popu-
andlowerstiffnessesareobservedasaresultofedgesoftening
lation for a given property.
in laminates containing off-axis plies. Because of this, the
δ—extensional displacement.
strengthandmodulusforangleplylaminatescanbedrastically
ε—general symbol for strain, whether normal strain or shear
underestimated. For quasi-isotropic laminates containing sig-
strain.
nificant 0° plies, the effect is not as significant.
ε—indicated normal strain from strain transducer or exten-
7. Apparatus
someter.
σ—normal stress.
7.1 Micrometers and Calipers—Amicrometer with a 4 to 7
ν—Poisson’s ratio. mm [0.16 to 0.28 in] nominal diameter ball interface shall be
D3039/D3039M − 17
used to measure the specimen thickness when at least one duringtensiletesting.InadditiontoPracticeE1012,thedegree
surface is irregular (such as the bag-side of a laminate). A of bending in a tensile system can also be evaluated using the
micrometer witha4to7mm [0.16 to 0.28 in.] nominal following related procedure. Specimen bending is considered
diameter ball interface or with a flat anvil interface shall be separately in 11.6.1.
usedtomeasurethespecimenthicknesswhenbothsurfacesare 7.2.5.1 A rectangular alignment coupon, preferably similar
smooth(suchastooledsurfaces).Amicrometerorcaliper,with in size and stiffness to the test specimen of interest, is
a flat anvil interface, shall be used to measure the width of the instrumented with a minimum of three longitudinal strain
specimen.Theaccuracyoftheinstrumentsshallbesuitablefor gages of similar type, two on the front face across the width
reading to within 1% of the sample dimensions. For typical and one on the back face of the specimen, as shown in Fig. 1.
specimen geometries, an instrument with an accuracy of Any difference in indicated strain between these gages during
60.0025 mm [60.0001 in.] is adequate for thickness loading provides a measure of the amount of bending in the
measurement,whileaninstrumentwithanaccuracyof 60.025 thickness plane (B ) and width plane (B ) of the coupon. The
y z
mm [60.001 in.] is adequate for width measurement. strain gage location should normally be located in the middle
of the coupon gage section (if modulus determination is a
7.2 Testing Machine—The testing machine shall be in con-
concern),nearagrip(ifprematuregripfailuresareaproblem),
formance with Practices E4 and shall satisfy the following
or any combination of these areas.
requirements:
7.2.5.2 Whenevaluatingsystemalignment,itisadvisableto
7.2.1 Testing Machine Heads—The testing machine shall
perform the alignment check with the same coupon inserted in
have both an essentially stationary head and a movable head.
each of the four possible installation permutations (described
7.2.2 Drive Mechanism—The testing machine drive mecha-
relative to the initial position): initial (top-front facing
nism shall be capable of imparting to the movable head a
observer),rotatedbacktofrontonly(topbackfacingobserver),
controlled velocity with respect to the stationary head. The
rotated end for end only (bottom front facing observer), and
velocity of the movable head shall be capable of being
rotated both front to back and end to end (bottom back facing
regulated as specified in 11.3.
observer). These four data sets provide an indication of
7.2.3 Force Indicator—The testing machine force-sensing
whether the bending is due to the system itself or to tolerance
device shall be capable of indicating the total force being
in the alignment check coupon or gaging.
carried by the test specimen. This device shall be essentially
7.2.5.3 The zero strain point may be taken either before
free from inertia lag at the specified rate of testing and shall
grippingoraftergripping.Thestrainresponseofthealignment
indicate the force with an accuracy over the force range(s) of
couponissubsequentlymonitoredduringthegrippingprocess,
interest of within 61% of the indicated value. The force
the tensile loading process, or both. Eq 1 and Eq 2 use these
range(s) of interest may be fairly low for modulus evaluation,
indicated strains to calculate the ratio of the percentage of
much higher for strength evaluation, or both, as required.
bending strain to average extensional strain for each bending
NOTE1—Obtainingprecisionforcedataoveralargerangeofinterestin
planeofthealignmentcoupon.Plottingpercentbendingversus
the same test, such as when both elastic modulus and ultimate force are
axial average strain is useful in understanding trends in the
being determined, place extreme requirements on the load cell and its
bending behavior of the system.
calibration. For some equipment, a special calibration may be required.
7.2.5.4 Problems with failures during gripping would be
For some combinations of material and load cell, simultaneous precision
reason to examine bending strains during the gripping process
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.
7.2.4 Grips—Each head of the testing machine shall carry
one grip for holding the test specimen so that the direction of
force applied to the specimen is coincident with the longitudi-
nalaxisofthespecimen.Thegripsshallapplysufficientlateral
pressure to prevent slippage between the grip face and the
coupon. If tabs are used the grips should be long enough that
they overhang the beveled portion of the tab by approximately
10to15mm[0.5in.].Itishighlydesirabletousegripsthatare
rotationally self-aligning to minimize bending stresses in the
coupon.
NOTE 2—Grip surfaces that are lightly serrated, approximately 1
serration/mm [25 serrations/in.], have been found satisfactory for use in
wedge-action grips when kept clean and sharp; coarse serrations may
produce grip-induced failures in untabbed coupons. Smooth gripping
surfaces have been used successfully with either hydraulic grips or an
emery cloth interface, or both.
7.2.5 System Alignment—Poor system alignment can be a
major contributor to premature failure, to elastic property data
scatter, or both. Practice E1012 describes bending evaluation
guidelines and describes potential sources of misalignment FIG. 1 Gage Locations for System Alignment Check Coupon
D3039/D3039M − 17
inthelocationnearthegrip.Concernovermodulusdatascatter weave. Some guidelines on the use of strain gages on compos-
would be reason to evaluate bending strains over the modulus ites follow. A general reference on the subject is Tuttle and
Brinson.
evaluation force range for the typical transducer location.
7.3.1.1 Surface preparation of fiber-reinforced composites
Excessive failures near the grips would be reason to evaluate
in accordance with Practice E1237 can penetrate the matrix
bending strains near the grip at high loading levels. While the
materialandcausedamagetothereinforcingfibersresultingin
maximum advisable amount of system misalignment is mate-
improper coupon failures. Reinforcing fibers should not be
rial and location dependent, good testing practice is generally
exposed or damaged during the surface preparation process.
abletolimitpercentbendingtoarangeof3to5%atmoderate
The strain gage manufacturer should be consulted regarding
strain levels (>1000 µε).Asystem showing excessive bending
surface preparation guidelines and recommended bonding
for the given application should be readjusted or modified.
agents for composites pending the development of a set of
ε 2ε
ave 3
standard practices for strain gage installation surface prepara-
B 5 3100 (1)
y
ε
ave
tion of fiber-reinforced composite materials.
2/3 ε 2ε
~ !
7.3.1.2 Consideration should be given to the selection of
2 1
B 5 3100 (2)
z
ε
gages having larger resistances to reduce heating effects on
ave
low-conductivity materials. Resistances of 350Ω or higher are
where:
preferred.Additional consideration should be given to the use
B = percent bending about system y axis (about
y
of the minimum possible gage excitation voltage consistent
the narrow plane), as calculated by Eq 1,%;
withthedesiredaccuracy(1to2Visrecommended)toreduce
B = percent bending about system z axis (about
z
further the power consumed by the gage. Heating of the
the wide plane), as calculated by Eq 2,%;
couponbythegagemayaffecttheperformanceofthematerial
ε , ε , and ε = indicated longitudinal strains displayed by
1 2 3
directly, or it may affect the indicated strain as a result of a
Gages1,2,and3,respectively,ofFig.1,µε;
difference between the gage temperature compensation factor
and
and the coefficient of thermal expansion of the coupon mate-
ε =((ε +ε )/2+ε )/2
ave 1 2 3
rial.
NOTE3—Experimentalerrormaybeintroducedbysourcessuchaspoor
7.3.1.3 Considerationofsomeformoftemperaturecompen-
system alignment, specimen preparation and strain gage precision and
sation is recommended, even when testing at standard labora-
calibration. These sources of error may result in an average calculated
tory atmosphere. Temperature compensation is required when
strain (ε ) of 0, causing B and B (Eq 1 and Eq 2) to approach infinity
ave y z
as the average calculated strain is the denominator. To minimize the
testing in nonambient temperature environments.
potential for this occurrence during system alignment evaluation, it is
7.3.1.4 Consideration should be given to the transverse
recommendedthatforcebeappliedtothealignmentcouponuntilallthree
sensitivity of the selected strain gage. The strain gage manu-
strain gages measure positive strain of no less than 500 µε with anε of
ave
facturer should be consulted for recommendations on trans-
no less than 1000 µε. If these conditions can not be met, the test
verse sensitivity corrections and effects on composites. This is
configuration should be adjusted prior to performing further system
alignment evaluation. particularly important for a transversely mounted gage used to
determine Poisson’s ratio, as discussed in Note 14.
7.3 Strain-Indicating Device—Force-straindata,ifrequired,
7.3.2 Extensometers—For most purposes, the extensometer
shallbedeterminedbymeansofeitherastraintransduceroran
gage length should be in the range of 10 to 50 mm [0.5 to 2.0
extensometer.Attachment of the strain-indicating device to the
in.]. Extensometers shall satisfy, at a minimum, Practice E83,
coupon shall not cause damage to the specimen surface. If
ClassB-1requirementsforthestrainrangeofinterestandshall
Poisson’s ratio is to be determined, the specimen shall be
becalibratedoverthatstrainrangeinaccordancewithPractice
instrumented to measure strain in both longitudinal and lateral
E83. For extremely stiff materials, or for measurement of
directions. If the modulus of elasticity is to be determined, the
transverse strains, the fixed error allowed by Class B-1
longitudinal strain should be simultaneously measured on
extensometers may be significant, in which case Class A
opposite faces of the specimen to allow for a correction as a
extensometersshouldbeconsidered.Theextensometershallbe
result of any bending of the specimen (see 11.6 for further
essentially free of inertia lag at the specified speed of testing,
guidance).
and the weight of the extensometer should not induce bending
7.3.1 Bonded Resistance Strain Gage Selection—Strain
strains greater than those allowed in 6.3.
gage selection is a compromise based on the type of material.
NOTE 4—It is generally less difficult to perform strain calibration on
An active gage length of 6 mm [0.25 in.] is recommended for
extensometers of longer gage length as less precision in displacement is
most materials. Active gage lengths should not be less than 3
required of the extensometer calibration device.
mm [0.125 in.]. Gage calibration certification shall comply
7.4 Conditioning Chamber—When conditioning materials
withTestMethodsE251.Whentestingwovenfabriclaminates,
at nonlaboratory environments, a temperature/vaporlevel-
gageselectionshouldconsidertheuseofanactivegagelength
controlledenvironmentalconditioningchamberisrequiredthat
thatisatleastasgreatasthecharacteristicrepeatingunitofthe
shall be capable of maintaining the required temperature to
3 4
A typical gage would have a 0.25-in. active gage length, 350-Ω resistance, a Tuttle, M. E. and Brinson, H. F., “Resistance-Foil Strain-Gage Technology as
strain rating of 3% or better, and the appropriate environmental resistance and Applied to Composite Materials,” Experimental Mechanics, Vol 24, No. 1, March
thermal coefficient. 1984; pp. 54–65; errata noted in Vol 26, No. 2, June 1986, pp. 153–154.
D3039/D3039M − 17
TABLE 1 Tensile Specimen Geometry Requirements
within 63°C [65°F] and the required relative vapor level to
within 63%.Chamberconditionsshallbemonitoredeitheron Parameter Requirement
an automated continuous basis or on a manual basis at regular Coupon Requirements:
shape constant rectangular cross-section
intervals.
minimum length gripping + 2 times width + gage length
A
specimen width as needed
7.5 Environmental Test Chamber—An environmental test
specimen width tolerance ±1 % of width
chamber is required for test environments other than ambient
specimen thickness as needed
testinglaboratoryconditions.Thischambershallbecapableof
specimen thickness tolerance ±4 % of thickness
specimen flatness flat with light finger pressure
maintaining the gage section of the test specimen at the
Tab Requirements (if used):
required test environment during the mechanical test.
tab material as needed
fiber orientation (composite tabs) as needed
8. Sampling and Test Specimens
tab thickness as needed
tab thickness variation between ±1 % tab thickness
8.1 Sampling—Test at least five specimens per test condi-
tabs
tionunlessvalidresultscanbegainedthroughtheuseoffewer tab bevel angle 5 to 90°, inclusive
tab step at bevel to specimen feathered without damaging specimen
specimens, such as in the case of a designed experiment. For
A
See 8.2.2 or Table 2 for recommendations.
statisticallysignificantdata,theproceduresoutlinedinPractice
E122 should be consulted. Report the method of sampling.
NOTE 5—If specimens are to undergo environmental conditioning to
result: acceptable failure mode and location. If acceptable
equilibrium, and are of such type or geometry that the weight change of
failuremodesoccurwithreasonablefrequency,thenthereisno
thematerialcannotbeproperlymeasuredbyweighingthespecimenitself
(suchasatabbedmechanicalcoupon),thenuseanothertravelercouponof
reason to change a given gripping method.
the same nominal thickness and appropriate size (but without tabs) to
8.2.2 Specific Recommendations:
determine when equilibrium has been reached for the specimens being
8.2.2.1 Width, Thickness, and Length—Select the specimen
conditioned.
width and thickness to promote failure in the gage section and
8.2 Geometry—Design of mechanical test coupons, espe-
assure that the specimen contains a sufficient number of fibers
cially those using end tabs, remains to a large extent an art
inthecrosssectiontobestatisticallyrepresentativeofthebulk
rather than a science, with no industry consensus on how to
material.Thespecimenlengthshouldnormallybesubstantially
approachtheengineeringofthegrippinginterface.Eachmajor
longer than the minimum requirement to minimize bending
composite testing laboratory has developed gripping methods
stresses caused by minor grip eccentricities. Keep the gage
for the specific material systems and environments commonly
sectionasfarfromthegripsasreasonablypossibleandprovide
encountered within that laboratory. Comparison of these meth-
a significant amount of material under stress and therefore
ods shows them to differ widely, making it extremely difficult
produce a more statistically significant result. The minimum
to recommend a universally useful approach or set of ap-
requirements for specimen design shown in Table 1 are by
proaches. Because of this difficulty, definition of the geometry
themselves insufficient to create a properly dimensioned and
of the test coupon is broken down into the following three
toleranced coupon drawing. Therefore, recommendations on
levels, which are discussed further in each appropriate section:
other important dimensions are provided for typical material
Purpose Degree of Geometry Definition
configurations in Table 2. These geometries have been found
by a number of testing laboratories to produce acceptable
8.2.1 General Requirements Mandatory Shape and Tolerances
failuremodesonawidevarietyofmaterialsystems,butuseof
8.2.2 Specific Recommendations Nonmandatory Suggested Dimensions
8.2.3 Detailed Examples Nonmandatory Typical Practices
them does not guarantee success for every existing or future
8.2.1 General Requirements: material system.
8.2.1.1 Shape, Dimensions, and Tolerances—The complete 8.2.2.2 Gripping/Use of Tabs—There are many material
list of requirements for specimen shape, dimensions, and configurations,suchasmultidirectionallaminates,fabric-based
tolerances is shown in Table 1. materials, or randomly reinforced sheet-molding compounds,
8.2.1.2 Use of Tabs—Tabs are not required. The key factor which can be successfully tested without tabs. However, tabs
intheselectionofspecimentolerancesandgrippingmethodsis are strongly recommended when testing unidirectional materi-
the successful introduction of force into the specimen and the als(orstronglyunidirectionallydominatedlaminates)tofailure
prevention of premature failure as a result of a significant in the fiber direction. Tabs may also be required when testing
discontinuity. Therefore, determine the need to use tabs, and unidirectional materials in the matrix direction to prevent
gripping damage.
specification of the major tab design parameters, by the end
A
TABLE 2 Tensile Specimen Geometry Recommendations
Fiber Width, Overall Length, Thickness, Tab Length, Tab Thickness, Tab Bevel
Orientation mm [in.] mm [in.] mm [in.] mm [in.] mm [in.] Angle,°
0° unidirectional 15 [0.5] 250 [10.0] 1.0 [0.040] 56 [2.25] 1.5 [0.062] 7 or 90
90° unidirectional 25 [1.0] 175 [ 7.0] 2.0 [0.080] 25 [1.0] 1.5 [0.062] 90
balanced and symmetric 25 [1.0] 250 [10.0] 2.5 [0.100] emery cloth — —
random-discontinuous 25 [1.0] 250 [10.0] 2.5 [0.100] emery cloth — —
A
Dimensions in this table and the tolerances of Fig. 2 or Fig. 3 are recommendations only and may be varied so long as the requirements of Table 1 are met.
D3039/D3039M − 17
8.2.2.3 Tab Geometry—Recommendations on important di- cient to create a properly dimensioned and toleranced coupon
mensions are provided for typical material configurations in drawing. Dimensionally toleranced specimen drawings for
Table 2. These dimensions have been found by a number of bothtabbedanduntabbedformsareshownasexamplesinFig.
testing laboratories to produce acceptable failure modes on a 2 (SI) and Fig. 3 (inch-pound). The tolerances on these
wide variety of material systems, but use of them does not drawings are fixed, but satisfy the requirements of Table 1 for
guarantee success for every existing or future material system. all of the recommended configurations of Table 2. For a
The selection of a tab configuration that can successfully specificconfiguration,thetolerancesonFig.2andFig.3might
produce a gage section tensile failure is dependent upon the be able to be relaxed.
coupon material, coupon ply orientation, and the type of grips
8.3 Specimen Preparation:
being used. When pressure-operated nonwedge grips are used
8.3.1 PanelFabrication—Controloffiberalignmentiscriti-
with care, squared-off 90° tabs have been used successfully.
cal. Improper fiber alignment will reduce the measured prop-
Wedge-operated grips have been used most successfully with
erties. Erratic fiber alignment will also increase the coefficient
tabshavinglowbevelangles(7to10°)andafeatheredsmooth
of variation. The specimen
...

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: D3039/D3039M − 14 D3039/D3039M − 17
Standard Test Method for
Tensile Properties of Polymer Matrix Composite Materials
This standard is issued under the fixed designation D3039/D3039M; 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 in-plane tensile properties of polymer matrix composite materials reinforced by
high-modulus fibers. The composite material forms are limited to continuous fiber or discontinuous fiber-reinforced composites in
which the laminate is balanced and symmetric with respect to the test direction.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the
inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must
be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
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 safety, health, and healthenvironmental 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.
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
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E83 Practice for Verification and Classification of Extensometer Systems
E111 Test Method for Young’s Modulus, Tangent Modulus, and Chord Modulus
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
E132 Test Method for Poisson’s Ratio at Room Temperature
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E251 Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
E456 Terminology Relating to Quality and Statistics
E1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial Force
Application
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 May 15, 2014Oct. 15, 2017. Published May 2014November 2017. Originally approved in 1971. Last previous edition approved in 20082014
as D3039 – 08.D3039/D3039M – 14. DOI: 10.1520/D3039_D3039M-14.10.1520/D3039_D3039M-17.
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
D3039/D3039M − 17
E1237 Guide for Installing Bonded Resistance Strain Gages
3. Terminology
3.1 Definitions—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 and Practice
E177 define terms relating to statistics. In the event of a conflict between terms, Terminology D3878 shall have precedence over
the other standards.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 Note—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.
3.2.2 nominal value, n—a value, existing in name only, assigned to a measurable property for the purpose of convenient
designation. Tolerances may be applied to a nominal value to define an acceptable range for the property.
3.2.3 transition region, n—a strain region of a stress-strain or strain-strain curve over which a significant change in the slope
of the curve occurs within a small strain range.
transition
3.2.4 transition strain, ε [nd],n—the strain value at the mid range of the transition region between the two essentially
linear portions of a bilinear stress-strain or strain-strain curve.
3.2.4.1 Discussion—
Many filamentary composite materials show essentially bilinear behavior during force application, such as seen in plots of either
longitudinal stress versus longitudinal strain or transverse strain versus long longitudinal strain. There are varying physical reasons
for the existence of a transition region. Common examples include: matrix cracking under tensile force application and ply
delamination.
3.3 Symbols:
A—minimum—average cross-sectional area of a coupon.
B —percent bending for a uniaxial coupon of rectangular cross section about y axis of the specimen (about the narrow direction).
y
B —percent bending for a uniaxial coupon of rectangular cross section about z axis of the specimen (about the wide direction).
z
CV—coefficient of variation statistic of a sample population for a given property (in percent).
E—modulus of elasticity in the test direction.
tu
F —ultimate tensile strength in the test direction.
su
F —ultimate shear strength in the test direction.
h—coupon thickness.
L —extensometer gage length.
g
L —minimum required bonded tab length.
min
n—number of coupons per sample population.
P—force carried by test coupon.
f
P —force carried by test coupon at failure.
max
P —maximum force carried by test coupon before failure.
s —standard deviation statistic of a sample population for a given property.
n−1
w—coupon width.
x —test result for an individual coupon from the sample population for a given property.
i
x¯—mean or average (estimate of mean) of a sample population for a given property.
δ—extensional displacement.
ε—general symbol for strain, whether normal strain or shear strain.
ε—indicated normal strain from strain transducer or extensometer.
σ—normal stress.
ν—Poisson’s ratio.
4. Summary of Test Method
4.1 A thin flat strip of material having a constant rectangular cross section is mounted in the grips of a mechanical testing
machine and monotonically loaded in tension while recording the force. The ultimate strength of the material can be determined
from the maximum force carried before failure. If the coupon strain is monitored with strain or displacement transducers then the
stress-strain response of the material can be determined, from which the ultimate tensile strain, tensile modulus of elasticity,
Poisson’s ratio, and transition strain can be derived.
D3039/D3039M − 17
5. Significance and Use
5.1 This test method is designed to produce tensile property data for material specifications, research and development, quality
assurance, and structural design and analysis. Factors that influence the tensile 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. Properties, in the test direction, which may be obtained from this test method include the following:
5.1.1 Ultimate tensile strength,
5.1.2 Ultimate tensile strain,
5.1.3 Tensile chord modulus of elasticity,
5.1.4 Poisson’s ratio, and
5.1.5 Transition strain.
6. Interferences
6.1 Material and Specimen Preparation—Poor material fabrication practices, lack of control of fiber alignment, and damage
induced by improper coupon machining are known causes of high material data scatter in composites.
6.2 Gripping—A high percentage of grip-induced failures, especially when combined with high material data scatter, is an
indicator of specimen gripping problems. Specimen gripping methods are discussed further in 7.2.4, 8.2, and 11.5.
6.3 System Alignment—Excessive bending will cause premature failure, as well as highly inaccurate modulus of elasticity
determination. Every effort should be made to eliminate excess bending from the test system. Bending may occur as a result of
misaligned grips or from specimens themselves if improperly installed in the grips or out-of-tolerance caused by poor specimen
preparation. If there is any doubt as to the alignment inherent in a given test machine, then the alignment should be checked as
discussed in 7.2.5.
6.4 Edge Effects in Angle Ply Laminates—Premature failure and lower stiffnesses are observed as a result of edge softening in
laminates containing off-axis plies. Because of this, the strength and modulus for angle ply laminates can be drastically
underestimated. For quasi-isotropic laminates containing significant 0° plies, the effect is not as significant.
7. Apparatus
7.1 Micrometers and Calipers—A micrometer with a 4 to 7 mm [0.16 to 0.28 in] nominal diameter ball interface shall be used
to measure the specimen thickness when at least one surface is irregular (such as the bag-side of a laminate). A micrometer with
a 4 to 7 mm [0.16 to 0.28 in.] nominal diameter ball interface or with a flat anvil interface shall be used to measure the specimen
thickness when both surfaces are smooth (such as tooled surfaces). A micrometer or caliper, with a flat anvil interface, shall be used
to measure the width of the specimen. The accuracy of the instruments shall be suitable for reading to within 1 % of the sample
dimensions. For typical specimen geometries, an instrument with an accuracy of 60.0025 mm [60.0001 in.] is adequate for
thickness measurement, while an instrument with an accuracy of 60.025 mm [60.001 in.] is adequate for width measurement.
7.2 Testing Machine—The testing machine shall be in conformance with Practices E4 and shall satisfy the following
requirements:
7.2.1 Testing Machine Heads—The testing machine shall have both an essentially stationary head and a movable head.
7.2.2 Drive Mechanism—The testing machine drive mechanism 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.
7.2.3 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.
NOTE 1—Obtaining precision force data over a large range of interest in the same test, such as when both elastic modulus and ultimate force are being
determined, place 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.
7.2.4 Grips—Each head of the testing machine shall carry one grip for holding the test specimen so that the direction of force
applied to the specimen is coincident with the longitudinal axis of the specimen. The grips shall apply sufficient lateral pressure
to prevent slippage between the grip face and the coupon. If tabs are used the grips should be long enough that they overhang the
beveled portion of the tab by approximately 10 to 15 mm [0.5 in.]. It is highly desirable to use grips that are rotationally
self-aligning to minimize bending stresses in the coupon.
NOTE 2—Grip surfaces that are lightly serrated, approximately 1 serration/mm [25 serrations/in.], have been found satisfactory for use in wedge-action
grips when kept clean and sharp; coarse serrations may produce grip-induced failures in untabbed coupons. Smooth gripping surfaces have been used
successfully with either hydraulic grips or an emery cloth interface, or both.
D3039/D3039M − 17
7.2.5 System Alignment—Poor system alignment can be a major contributor to premature failure, to elastic property data scatter,
or both. Practice E1012 describes bending evaluation guidelines and describes potential sources of misalignment during tensile
testing. In addition to Practice E1012, the degree of bending in a tensile system can also be evaluated using the following related
procedure. Specimen bending is considered separately in 11.6.1.
7.2.5.1 A rectangular alignment coupon, preferably similar in size and stiffness to the test specimen of interest, is instrumented
with a minimum of three longitudinal strain gages of similar type, two on the front face across the width and one on the back face
of the specimen, as shown in Fig. 1. Any difference in indicated strain between these gages during loading provides a measure of
the amount of bending in the thickness plane (B ) and width plane (B ) of the coupon. The strain gage location should normally
y z
be located in the middle of the coupon gage section (if modulus determination is a concern), near a grip (if premature grip failures
are a problem), or any combination of these areas.
7.2.5.2 When evaluating system alignment, it is advisable to perform the alignment check with the same coupon inserted in each
of the four possible installation permutations (described relative to the initial position): initial (top-front facing observer), rotated
back to front only (top back facing observer), rotated end for end only (bottom front facing observer), and rotated both front to
back and end to end (bottom back facing observer). These four data sets provide an indication of whether the bending is due to
the system itself or to tolerance in the alignment check coupon or gaging.
7.2.5.3 The zero strain point may be taken either before gripping or after gripping. The strain response of the alignment coupon
is subsequently monitored during the gripping process, the tensile loading process, or both. Eq 1 and Eq 2 use these indicated
strains to calculate the ratio of the percentage of bending strain to average extensional strain for each bending plane of the
alignment coupon. Plotting percent bending versus axial average strain is useful in understanding trends in the bending behavior
of the system.
7.2.5.4 Problems with failures during gripping would be reason to examine bending strains during the gripping process in the
location near the grip. Concern over modulus data scatter would be reason to evaluate bending strains over the modulus evaluation
force range for the typical transducer location. Excessive failures near the grips would be reason to evaluate bending strains near
the grip at high loading levels. While the maximum advisable amount of system misalignment is material and location dependent,
good testing practice is generally able to limit percent bending to a range of 3 to 5 % at moderate strain levels (>1000 με). A system
showing excessive bending for the given application should be readjusted or modified.
ε 2 ε
ave 3
B 5 3100 (1)
y
ε
ave
2/3 ~ε 2 ε !
2 1
B 5 3100 (2)
z
ε
ave
where:
B = percent bending about system y axis (about the narrow plane), as calculated by Eq 1, %;
y
B = percent bending about system z axis (about the wide plane), as calculated by Eq 2, %;
z
ε , ε , and ε = indicated longitudinal strains displayed by Gages 1, 2, and 3, respectively, of Fig. 1, με; and
1 2 3
ε = ((ε + ε )/2 + ε )/2
ave 1 2 3
NOTE 3—Experimental error may be introduced by sources such as poor system alignment, specimen preparation and strain gage precision and
calibration. These sources of error may result in an average calculated strain (ε ) of 0, causing B and B (Eq 1 and Eq 2) to approach infinity as the
ave y z
FIG. 1 Gage Locations for System Alignment Check Coupon
D3039/D3039M − 17
average calculated strain is the denominator. To minimize the potential for this occurrence during system alignment evaluation, it is recommended that
force be applied to the alignment coupon until all three strain gages measure positive strain of no less than 500 με with an ε of no less than 1000 με.
ave
If these conditions can not be met, the test configuration should be adjusted prior to performing further system alignment evaluation.
7.3 Strain-Indicating Device—Force-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 coupon shall not cause damage to the specimen surface. If Poisson’s
ratio is to be determined, the specimen shall be instrumented to measure strain in both longitudinal and lateral directions. If the
modulus of elasticity is to be determined, the longitudinal strain should be simultaneously measured on opposite faces of the
specimen to allow for a correction as a result of any bending of the specimen (see 11.6 for further guidance).
7.3.1 Bonded Resistance Strain Gage Selection—Strain gage selection is a compromise based on the type of material. An active
gage length of 6 mm [0.25 in.] is recommended for most materials. Active gage lengths should not be less than 3 mm [0.125 in.].
Gage calibration certification shall comply with Test Methods E251. When testing woven fabric laminates, gage selection should
consider the use of an active gage length that is at least as great as the characteristic repeating unit of the weave. Some guidelines
on the use of strain gages on composites follow. A general reference on the subject is Tuttle and Brinson.
7.3.1.1 Surface preparation of fiber-reinforced composites in accordance with Practice E1237 can penetrate the matrix material
and cause damage to the reinforcing fibers resulting in improper coupon failures. Reinforcing fibers should not be exposed or
damaged during the surface preparation process. The strain gage manufacturer should be consulted regarding surface preparation
guidelines and recommended bonding agents for composites pending the development of a set of standard practices for strain gage
installation surface preparation of fiber-reinforced composite materials.
7.3.1.2 Consideration should be given to the selection of gages having larger resistances to reduce heating effects on
low-conductivity materials. Resistances of 350 Ω or higher are preferred. Additional consideration should be given to the use of
the minimum possible gage excitation voltage consistent with the desired accuracy (1 to 2 V is recommended) to reduce further
the power consumed by the gage. Heating of the coupon by the gage may affect the performance of the material directly, or it may
affect the indicated strain as a result of a difference between the gage temperature compensation factor and the coefficient of
thermal expansion of the coupon material.
7.3.1.3 Consideration of some form of temperature compensation is recommended, even when testing at standard laboratory
atmosphere. Temperature compensation is required when testing in nonambient temperature environments.
7.3.1.4 Consideration should be given to the transverse sensitivity of the selected strain gage. The strain gage manufacturer
should be consulted for recommendations on transverse sensitivity corrections and effects on composites. This is particularly
important for a transversely mounted gage used to determine Poisson’s ratio, as discussed in Note 1314.
7.3.2 Extensometers—For most purposes, the extensometer gage length should be in the range of 10 to 50 mm [0.5 to 2.0 in.].
Extensometers shall satisfy, at a minimum, Practice E83, Class B-1 requirements for the strain range of interest and shall be
calibrated over that strain range in accordance with Practice E83. For extremely stiff materials, or for measurement of transverse
strains, the fixed error allowed by Class B-1 extensometers may be significant, in which case Class A extensometers should be
considered. The extensometer shall be essentially free of inertia lag at the specified speed of testing, and the weight of the
extensometer should not induce bending strains greater than those allowed in 6.3.
NOTE 4—It is generally less difficult to perform strain calibration on extensometers of longer gage length as less precision in displacement is required
of the extensometer calibration device.
7.4 Conditioning Chamber—When conditioning materials at nonlaboratory environments, a temperature/vaporlevel-controlled
environmental conditioning chamber is required that shall be capable of maintaining the required temperature to within 63°C
[65°F] and the required relative 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 gage section of the test specimen at the required test
environment during the mechanical test.
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, such as in the case of a designed experiment. For statistically significant data, the procedures outlined in Practice E122
should be consulted. Report the method of sampling.
NOTE 5—If specimens are to undergo environmental conditioning to equilibrium, and are of such type or geometry that the weight change of the
material cannot be properly measured by weighing the specimen itself (such as a tabbed mechanical coupon), then use another traveler coupon of the
same nominal thickness and appropriate size (but without tabs) to determine when equilibrium has been reached for the specimens being conditioned.
A typical gage would have a 0.25-in. active gage length, 350-Ω resistance, a strain rating of 3 % or better, and the appropriate environmental resistance and thermal
coefficient.
Tuttle, M. E. and Brinson, H. F., “Resistance-Foil Strain-Gage Technology as Applied to Composite Materials,” Experimental Mechanics, Vol 24, No. 1, March 1984;
pp. 54–65; errata noted in Vol 26, No. 2, June 1986, pp. 153–154.
D3039/D3039M − 17
8.2 Geometry—Design of mechanical test coupons, especially those using end tabs, remains to a large extent an art rather than
a science, with no industry consensus on how to approach the engineering of the gripping interface. Each major composite testing
laboratory has developed gripping methods for the specific material systems and environments commonly encountered within that
laboratory. Comparison of these methods shows them to differ widely, making it extremely difficult to recommend a universally
useful approach or set of approaches. Because of this difficulty, definition of the geometry of the test coupon is broken down into
the following three levels, which are discussed further in each appropriate section:
Purpose Degree of Geometry Definition
8.2.1 General Requirements Mandatory Shape and Tolerances
8.2.2 Specific Recommendations Nonmandatory Suggested Dimensions
8.2.3 Detailed Examples Nonmandatory Typical Practices
8.2.1 General Requirements:
8.2.1.1 Shape, Dimensions, and Tolerances—The complete list of requirements for specimen shape, dimensions, and tolerances
is shown in Table 1.
8.2.1.2 Use of Tabs—Tabs are not required. The key factor in the selection of specimen tolerances and gripping methods is the
successful introduction of force into the specimen and the prevention of premature failure as a result of a significant discontinuity.
Therefore, determine the need to use tabs, and specification of the major tab design parameters, by the end result: acceptable failure
mode and location. If acceptable failure modes occur with reasonable frequency, then there is no reason to change a given gripping
method.
8.2.2 Specific Recommendations:
8.2.2.1 Width, Thickness, and Length—Select the specimen width and thickness to promote failure in the gage section and assure
that the specimen contains a sufficient number of fibers in the cross section to be statistically representative of the bulk material.
The specimen length should normally be substantially longer than the minimum requirement to minimize bending stresses caused
by minor grip eccentricities. Keep the gage section as far from the grips as reasonably possible and provide a significant amount
of material under stress and therefore produce a more statistically significant result. The minimum requirements for specimen
design shown in Table 1 are by themselves insufficient to create a properly dimensioned and toleranced coupon drawing. Therefore,
recommendations on other important dimensions are provided for typical material configurations in Table 2. These geometries have
been found by a number of testing laboratories to produce acceptable failure modes on a wide variety of material systems, but use
of them does not guarantee success for every existing or future material system.
8.2.2.2 Gripping/Use of Tabs—There are many material configurations, such as multidirectional laminates, fabric-based
materials, or randomly reinforced sheet-molding compounds, which can be successfully tested without tabs. However, tabs are
strongly recommended when testing unidirectional materials (or strongly unidirectionally dominated laminates) to failure in the
fiber direction. Tabs may also be required when testing unidirectional materials in the matrix direction to prevent gripping damage.
8.2.2.3 Tab Geometry—Recommendations on important dimensions are provided for typical material configurations in Table 2.
These dimensions have been found by a number of testing laboratories to produce acceptable failure modes on a wide variety of
material systems, but use of them does not guarantee success for every existing or future material system. The selection of a tab
configuration that can successfully produce a gage section tensile failure is dependent upon the coupon material, coupon ply
orientation, and the type of grips being used. When pressure-operated nonwedge grips are used with care, squared-off 90° tabs have
been used successfully. Wedge-operated grips have been used most successfully with tabs having low bevel angles (7 to 10°) and
a feathered smooth transition into the coupon. For alignment purposes, it is essential that the tabs be of matched thickness.
8.2.2.4 Friction Tabs—Tabs need not always be bonded to the material under test to be effective in introducing the force into
the specimen. Friction tabs, essentially nonbonded tabs held in place by the pressure of the grip, and often used with emery cloth
TABLE 1 Tensile Specimen Geometry Requirements
Parameter Requirement
Coupon Requirements:
shape constant rectangular cross-section
minimum length gripping + 2 times width + gage length
A
specimen width as needed
specimen width tolerance ±1 % of width
specimen thickness as needed
specimen thickness tolerance ±4 % of thickness
specimen flatness flat with light finger pressure
Tab Requirements (if used):
tab material as needed
fiber orientation (composite tabs) as needed
tab thickness as needed
tab thickness variation between ±1 % tab thickness
tabs
tab bevel angle 5 to 90°, inclusive
tab step at bevel to specimen feathered without damaging specimen
A
See 8.2.2 or Table 2 for recommendations.
D3039/D3039M − 17
A
TABLE 2 Tensile Specimen Geometry Recommendations
Fiber Width, Overall Length, Thickness, Tab Length, Tab Thickness, Tab Bevel
Orientation mm [in.] mm [in.] mm [in.] mm [in.] mm [in.] Angle,°
0° unidirectional 15 [0.5] 250 [10.0] 1.0 [0.040] 56 [2.25] 1.5 [0.062] 7 or 90
90° unidirectional 25 [1.0] 175 [ 7.0] 2.0 [0.080] 25 [1.0] 1.5 [0.062] 90
balanced and symmetric 25 [1.0] 250 [10.0] 2.5 [0.100] emery cloth — —
random-discontinuous 25 [1.0] 250 [10.0] 2.5 [0.100] emery cloth — —
A
Dimensions in this table and the tolerances of Fig. 2 or Fig. 3 are recommendations only and may be varied so long as the requirements of Table 1 are met.
or some other light abrasive between the tab and the coupon, have been successfully used in some applications. In specific cases,
lightly serrated wedge grips (see Note 2) have been successfully used with only emery cloth as the interface between the grip and
the coupon. However, the abrasive used must be able to withstand significant compressive forces. Some types of emery cloth have
been found ineffective in this application because of disintegration of the abrasive.
8.2.2.5 Tab Material—The most consistently used bonded tab material has been continuous E-glass fiber-reinforced polymer
matrix materials (woven or unwoven) in a [0/90]ns laminate configuration. The tab material is commonly
...