ASTM D5379/D5379M-98
(Test Method)Standard Test Method for Shear Properties of Composite Materials by the V-Notched Beam Method
Standard Test Method for Shear Properties of Composite Materials by the V-Notched Beam Method
SCOPE
1.1 This test method determines 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 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.3 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.
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Designation:D5379/D5379M–98
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method determines the shear properties of 2.1 ASTM Standards:
composite materials reinforced by high-modulus fibers. The D792 TestMethodsforDensityandSpecificGravity(Rela-
composite materials are limited to continuous-fiber or tive Density) of Plastics by Displacement
discontinuous-fiber-reinforcedcompositesinthefollowingma- D883 Terminology Relating to Plastics
terial forms: D2584 Test Method for Ignition Loss of Cured Reinforced
1.1.1 Laminates composed only of unidirectional fibrous Resins
laminae, with the fiber direction oriented either parallel or D2734 Test Method for Void Content of Reinforced Plas-
perpendicular to the loading axis. tics
1.1.2 Laminatescomposedonlyofwovenfabricfilamentary D3171 Test Method for Fiber Content of Resin-Matrix
laminae with the warp direction oriented either parallel or Composites by Matrix Digestion
perpendicular to the loading axis. D3878 Terminology for Composite Materials
1.1.3 Laminates composed only of unidirectional fibrous D5229/D5229M Test Method for Moisture Absorption
laminae, containing equal numbers of plies oriented at 0 and Properties and Equilibrium Conditioning of Polymer Ma-
90°inabalancedandsymmetricstackingsequence,withthe0° trix Composite Materials
directionorientedeitherparallelorperpendiculartotheloading E4 Practices for Force Verification of Testing Machines
axis. E6 Terminology Relating to Methods of Mechanical Test-
1.1.4 Short-fiber-reinforced composites with a majority of ing
the fibers being randomly distributed. E111 TestMethodforYoung’sModulus,TangentModulus,
and Chord Modulus
NOTE 1—This shear test concept was originally developed without
E122 Practice for Choice of Sample Size to Estimate a
referencetofiberdirectionforuseonisotropicmaterialssuchasmetalsor
Measure of Quality for a Lot or Process
ceramics.
E177 Practice for Use of the Terms Precision and Bias in
1.2 This standard does not purport to address all of the
ASTM Test Methods
safety concerns, if any, associated with its use. It is the
E251 Test Methods for Performance Characteristics of
responsibility of the user of this standard to establish appro-
Metallic Bonded Resistance Strain Gages
priate safety and health practices and determine the applica-
E456 Terminology Relating to Quality and Statistics
bility of regulatory limitations prior to use.
E 1237 Guide for Installing Bonded Resistance Strain
1.3 The values stated in either SI units or inch-pound units
Gages
are to be regarded separately as standard. Within the text the
2.2 Other Documents:
inch-pound units are shown in brackets. The values stated in
ANSI Y14.5M-1982
each system are not exact equivalents; therefore, each system
ANSI/ASME B 46.1-1985
must be used independently of the other. Combining values
2.3 ASTM Adjuncts:
from the two systems may result in nonconformance with the
standard.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 08.02.
1 4
This test method is under the jurisdiction of ASTM Committee D-30 on Annual Book of ASTM Standards, Vol 15.03.
Composite Materials and is the direct responsibility of Subcommittee D30.04 on Annual Book of ASTM Standards, Vol 03.01.
Lamina and Laminate Test Methods. Annual Book of ASTM Standards, Vol 14.02.
Current edition approved Dec. 10, 1998. Published April 1999. Originally Available from American National Standards Institute, 11 W. 42nd St., 13th
published as D5379/D5379M-93. Last previous edition D5379/D5379M-93. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5379/D5379M
V-Notched Beam Shear Fixture Machining Drawings 3.3 Symbols:
3.3.1 A—minimum cross-sectional area of a coupon.
3. Terminology
3.3.2 CV—coefficient of variation statistic of a sample
3.1 Definitions—Terminology D3878 defines terms relat-
population for a given property (in percent).
su
ing to high-modulus fibers and their composites. Terminology
3.3.3 F — ultimate shear strength in the test direction.
u
D883 defines terms relating to plastics. Terminology E6
3.3.4 F — ultimate strength in the test direction.
defines terms relating to mechanical testing. Terminology
3.3.5 F° (offset)— the value of the shear stress at the
E456 and Practice E177 define terms relating to statistics. In
intersection of the shear chord modulus of elasticity and the
the event of a conflict between terms, Terminology D3878
stress strain curve, when the modulus is offset along the shear
shall have precedence over the other standards.
strain axis from the origin by the reported strain offset value.
3.2 Definitions of Terms Specific to This Standard:
3.3.6 G—shear modulus of elasticity in the test direction.
NOTE 2—If the term represents a physical quantity, its analytical 3.3.7 h—coupon thickness.
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
3.3.8 n—number of coupons per sample population.
fundamental dimension form, using the following ASTM standard sym-
3.3.9 P—load carried by test coupon.
bology for fundamental dimensions, shown within square brackets: [M]
f
3.3.10 P— load carried by test coupon at failure.
formass,[L]forlength,[T]fortime,[Q]forthermodynamictemperature,
max
3.3.11 P — maximum load carried by test coupon before
and[nd]fornondimensionalquantities.Useofthesesymbolsisrestricted
to analytical dimensions when used with square brackets, as the symbols failure.
may have other definitions when used without the brackets.
3.3.12 s —standard deviation statistic of a sample popu-
n−1
lation for a given property.
3.2.1 in-planeshear,n—anyoftheshearpropertiesdescrib-
3.3.13 w—coupon width.
ing the response resulting from a shear load or deformation
3.3.14 x— test result for an individual coupon from the
applied to the 1-2 material plane. (See also material coordinate
i
system.) sample population for a given property.
3.2.2 interlaminar shear, n—any of the shear properties 3.3.15 x¯—mean or average (estimate of mean) of a sample
describing the response resulting from a shear load or defor- population for a given property.
mation applied to the 1-3 or 2-3 material planes. (See also 3.3.16 g—shear strain.
material coordinate system.)
3.3.17 e—general symbol for strain, whether normal strain
3.2.3 materialcoordinatesystem,n—aCartesiancoordinate
or shear strain.
system describing the principal material coordinate system,
3.3.18 e—indicated normal strain from strain transducer or
using 1, 2, and 3 for the axes, as shown in Fig. 1.
extensometer.
3.2.4 nominal value, n— a value, existing in name only,
3.3.19 s—normal stress.
assigned to a measurable property for the purpose of conve-
3.3.20 t—shear stress.
nient designation. Tolerances may be applied to a nominal
3.3.21 u—ply orientation angle.
value to define an acceptable range for the property.
3.2.5 shear strength, n—the shear stress carried by a mate-
4. Summary of Test Method
rial at failure under a pure shear condition.
4.1 Amaterial coupon in the form of a rectangular flat strip
3.2.5.1 Discussion—Therearenostandardtestmethodsthat
withsymmetricalcentrallylocatedv-notches,shownschemati-
arecapableofproducingaperfectlypureshearstresscondition
cally in Fig. 2, is loaded in a mechanical testing machine by a
to failure for every material, although some test methods can
special fixture (shown schematically in Fig. 3 and in more
come acceptably close for a specific material for a given
detail in the machining drawings of ASTM Adjunct
engineering purpose.
ADJD5379).
4.2 The specimen is inserted into the fixture with the notch
AvailablefromASTMHeadquarters,100BarrHarborDr.,POBoxC700,West
located along the line of action of loading by means of an
Conshohocken, PA 19428–2959. Order Adjunct ADJD5379.
alignmenttoolthatreferencesthefixture.Thetwohalvesofthe
fixture are compressed by a testing machine while monitoring
load. The relative displacement between the two fixture halves
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.
The specimen and fixture are based upon work at the University of Wyoming
Composite Materials Research Group (1,2), and were subsequently modified by the
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
historical perspectives are given in Refs (1,17)). The boldface numbers in paren-
FIG. 1 Material Coordinate System theses refer to the list of references at the end of this standard.
D5379/D5379M
Nominal Specimen Dimensions
d 5 20.0 mm [0.75 in.]
d 5 4.0 mm [0.15 in.]
h 5 as required
L 5 76.0 mm [3.0 in.]
r 5 1.3 mm [0.05 in.]
w 5 12.0 mm [0.45 in.]
FIG. 2 V-Notched Beam Test Coupon Schematic
NOTE 1—The value of the dimension b is not critical to the concept.
FIG. 4 Idealized Force, Shear, and Moment Diagrams
5. 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,
FIG. 3 V-Notched Beam Test Fixture Schematic
depending upon the orientation of the material coordinate
system relative to the loading axis. Factors that influence the
4.3 The loading can be idealized as asymmetric flexure, as
shear response and should therefore be reported include the
shownbytheshearandbendingmomentdiagramsofFig.4. .
following: material, methods of material preparation and lay-
The notches influence the shear strain along the loading
up, specimen stacking sequence, specimen preparation, speci-
direction, making the distribution more uniform than would be
men conditioning, environment of testing, specimen alignment
seen without the notches. While the degree of uniformity is a
and gripping, speed of testing, time at temperature, void
function of material orthotropy, the best overall results, when
content, and volume percent reinforcement.
testing in the 1-2 plane, have been obtained on [0/90]ns-type
5.2 In anisotropic materials, properties may be obtained in
laminates.
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
While the idealization indicates constant shear loading and zero bending
evaluated for any given specimen. Properties, in the test
momentinthespecimenatthenotches,theactualloadapplicationisdistributedand
direction, which may be obtained from this test method,
imperfect, which contributes to asymmetry in the shear strain distribution and to a
component of normal stress that is particularly deleterious to [90]n specimens (16). include the following:
D5379/D5379M
5.2.1 Shear stress/strain response, result of material orthotropy. Recommendations for notch
5.2.2 Ultimate strength, dimensions versus degree of material orthotropy are still being
5.2.3 Ultimate strain, developed. In the interim, and in order to minimize the
5.2.4 Shear chord modulus of elasticity, and complexity of this test method, a single standard geometry has
5.2.5 Transition strain. been adopted. However, variations to the notch angle, depth,
and radius for the purpose of optimizing the specimen perfor-
mance for a particular material are acceptable when the
6. Interferences
variations are clearly noted in the report.
6.1 Material and Specimen Preparation—Poor material
6.6 Determination of Failure:
fabrication practices, lack of control of fiber alignment, and
6.6.1 [0]n Materials—In [0]n specimens tested in the 1-2
damage induced by improper coupon machining are known
plane, a visible crack typically develops at the notch root,
causes of high material data scatter in composites.
causing a small drop in load before ultimate failure, as shown
6.2 Materials and Coarse Structure—Oneofthefundamen-
in Fig. 5. The small load drop accompanying the notch root
tal assumptions of this test method is that the material must be
crack is not considered the failure load; rather the load that
relatively homogeneous with respect to the size of the test
accompanies failure in the test section shall be used as the
section. Materials that have relatively coarse features with
failure load.
respect to the test section dimensions, such as fabrics using
6.6.2 [90]n Materials—In[90]nspecimenstestedinthe2-1
large filament count tows (such as tows of 12000 filaments or
plane, the ultimate failure load is clearly defined by the
more) or certain braided structures, should not be tested with
maximum load attained on the load-deflection curve.
this specimen size. Scale-up of the specimen and the fixturing
6.6.3 [0/90]ns, SMC, Toughened Materials—For [0/90]ns,
to accommodate such materials is possible, but is beyond the
SMC, or toughened materials, the shear failure load may be
scope of this test method.
lower than the maximum load attainable during the test. In
6.3 Elastic Modulus Measurement—Thecalculationsinthis
such materials, the fibers may reorient following shear failure,
test method assume a uniform shear stress state between the
subsequentlyallowingthefiberstocarryamajorportionofthe
notches. The actual degree of uniformity varies with the level
load. This reorientation is more likely to occur in composites
of material orthotropy and the direction of loading. Both
with tough matrix materials that are very nonlinear in shear or
analysis and full-field experimental strain measurement have
in laminates containing off-axis fibers. In such cases, the shear
shownthatwhentestinginthe1-2plane,[0]nspecimensresult
failure load can often be determined by correlating visual
in an elastic modulus estimate that is too high (about 10% too
observation of failure in the test section with a load drop or by
high for carbon/epoxy), while [90]n specimens of the same
a significant change in the slope of the load-displacement plot,
material result
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