ASTM D2344/D2344M-00e1
(Test Method)Standard Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their Laminates
Standard Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their Laminates
SCOPE
1.1 This test method determines the short-beam strength of high-modulus fiber-reinforced composite materials. The specimen is a short beam machined from a curved or a flat laminate up to 6.00 mm [0.25 in.] thick. The beam is loaded in three-point bending.
1.2 Application of this test method is limited to continuous- or discontinuous-fiber-reinforced polymer matrix composites, for which the elastic properties are balanced and symmetric with respect to the longitudinal axis of the beam.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and 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. The values stated in each system may not be 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
e1
Designation: D 2344/D 2344M – 00
Standard Test Method for
Short-Beam Strength of Polymer Matrix Composite Materials
and Their Laminates
This standard is issued under the fixed designation D 2344/D 2344M; 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.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—The title has been editorially corrected in November 2000.
1. Scope Composites by Matrix Digestion
D 3878 Terminology for High-Modulus Reinforcing Fibers
1.1 This test method determines the short-beam strength of
and Their Composites
high-modulus fiber-reinforced composite materials. The speci-
D 5229/D 5229M Test Method for Moisture Absorption
men is a short beam machined from a curved or a flat laminate
Properties and Equilibrium Conditioning of Polymer Ma-
up to 6.00 mm [0.25 in.] thick. The beam is loaded in
trix Composite Materials
three-point bending.
D 5687/D 5687M Guide for Preparation of Flat Composite
1.2 Application of this test method is limited to continuous-
Panels with Processing Guidelines for Specimen Prepara-
or discontinuous-fiber-reinforced polymer matrix composites,
tion
for which the elastic properties are balanced and symmetric
E 4 Practices for Force Verification of Testing Machines
with respect to the longitudinal axis of the beam.
E 6 Terminology Relating to Methods of Mechanical Test-
1.3 This standard does not purport to address all of the
ing
safety concerns, if any, associated with its use. It is the
E 18 Test Methods for Rockwell Hardness and Rockwell
responsibility of the user of this standard to establish appro-
Superficial Hardness of Metallic Materials
priate safety and health practices and determine the applica-
E 122 Practice for Choice of Sample Size to Estimate a
bility of regulatory limitations prior to use.
Measure of Quality for a Lot or Process
1.4 The values stated in either SI units or inch-pound units
E 177 Practice for Use of the Terms Precision and Bias in
are to be regarded separately as standard. The values stated in
ASTM Test Methods
each system may not be exact equivalents; therefore, each
E 456 Terminology Relating to Quality and Statistics
system must be used independently of the other. Combining
E 1309 Guide for Identification of Composite Materials in
values from the two systems may result in nonconformance
Computerized Material Property Databases
with the standard.
E 1434 Guide for Development of Standard Data Records
2. Referenced Documents for Computerization of Mechanical Test Data for High-
Modulus Fiber-Reinforced Composite Materials
2.1 ASTM Standards:
E 1471 Guide for Identification of Fibers, Fillers, and Core
D 792 TestMethodsforDensityandSpecificGravity(Rela-
Materials in Computerized Material Property Databases
tive Density) of Plastics by Displacement
D 883 Terminology Relating to Plastics
3. Terminology
D 2584 Test Method for Ignition Loss of Cured Reinforced
3.1 Definitions—Terminology D 3878 defines the terms re-
Resins
lating to high-modulus fibers and their composites. Terminol-
D 2734 Test Method for Void Content of Reinforced Plas-
ogy D 883 defines terms relating to plastics. Terminology E 6
tics
defines terms relating to mechanical testing. Terminology
D 3171 Test Method for Fiber Content of Resin-Matrix
E 456 and Practice E 177 define terms relating to statistics. In
the event of a conflict between definitions, Terminology
D 3878 shall have precedence over the other documents.
This test method is under the jurisdiction of ASTM Committee D-30 on
NOTE 1—If the term represents a physical quantity, its analytical
Composite Materials and is the direct responsibility of Subcommittee D30.04 on
Lamina and Laminate Test Methods.
Current edition approved March 10, 2000. Published June 2000. Originally
published as D 2344 – 65 T. Last previous edition D 2344 – 84 (1995). Annual Book of ASTM Standards, Vol 15.03.
2 5
Annual Book of ASTM Standards, Vol 08.01. Annual Book of ASTM Standards, Vol 03.01.
3 6
Annual Book of ASTM Standards, Vol 08.02. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 2344/D 2344M
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
fundamental dimension form, using the following ASTM standard sym-
bology for fundamental dimensions, shown within square brackets: [M]
for mass, [L] for length, [T] for time, [Q] for thermodynamic temperature,
and [nd] for nondimensional quantities. Use of these symbols is restricted
to analytical dimensions when used with square brackets, as the symbols
may have other definitions when used without the brackets.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 balanced laminate, n—a continuous fiber-reinforced
laminateinwhicheach+ulamina,measuredwithrespecttothe
laminate reference axis, is balanced by a –u lamina of the same
material (for example, [0/+45/–45/+45/–45/0]).
3.2.2 short-beam strength, n—the shear stress as calculated
in Eq 1, developed at the specimen mid-plane at the failure
event specified in 11.6.
3.2.2.1 Discussion—Althoughshearisthedominantapplied
loading in this test method, the internal stresses are complex
andavarietyoffailuremodescanoccur.Elasticitysolutionsby
Bergetal (1) , Whitney (2), and Sullivan and Van Oene (3)
have all demonstrated inadequacies in classical beam theory in
defining the stress state in the short-beam configuration. These
solutions show that the parabolic shear-stress distribution as
predicted by Eq 1 only occurs, and then not exactly, on planes
midway between the loading nose and support points. Away
fromtheseplanes,thestressdistributionsbecomeskewed,with
peak stresses occurring near the loading nose and support
points. Of particular significance is the stress state local to the
loading nose in which the severe shear-stress concentration
combined with transverse and in-plane compressive stresses
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/
ASM B46.1-1986.
has been shown to initiate failure. However, for the more
NOTE 2—Ply orientation tolerance 60.5° relative to –B–.
ductile matrices, plastic yielding may alleviate the situation
FIG. 1 Flat Specimen Configuration (SI)
under the loading nose (1) and allow other failure modes to
occur such as bottom surface fiber tension (2). Consequently,
two supports that allow lateral motion, the load being applied
unless mid-plane interlaminar failure has been clearly ob-
by means of a loading nose directly centered on the midpoint
served, the short-beam strength determined from this test
of the test specimen.
method cannot be attributed to a shear property, and the use of
Eq 1 will not yield an accurate value for shear strength.
5. Significance and Use
3.2.3 symmetric laminate, n—a continuous fiber-reinforced
5.1 In most cases, because of the complexity of internal
laminate in which each ply above the mid-plane is identically
stresses and the variety of failure modes that can occur in this
matched (in terms of position, orientation, and mechanical
specimen, it is not generally possible to relate the short-beam
properties) with one below the mid-plane.
strength to any one material property. However, failures are
3.3 Symbols:
normally dominated by resin and interlaminar properties, and
b—specimen width.
the test results have been found to be repeatable for a given
CV—sample coefficient of variation (in percent).
sbs specimen geometry, material system, and stacking sequence
F —short-beam strength.
(4).
h—specimen thickness.
5.2 Short-beam strength determined by this test method can
n—number of specimens.
be used for quality control and process specification purposes.
P —maximum load observed during the test.
m
It can also be used for comparative testing of composite
x—measuredorderivedpropertyforanindividualspecimen
i
materials, provided that failures occur consistently in the same
from the sample population.
mode (5).
x¯—sample mean (average).
5.3 This test method is not limited to specimens within the
range specified in Section 8, but is limited to the use of a
4. Summary of Test Method
loading span length-to-specimen thickness ratio of 4.0 and a
4.1 The short-beam test specimens (Figs. 1-4) are center-
minimum specimen thickness of 2.0 mm [0.08 in.].
loaded as shown in Figs. 5 and 6. The specimen ends rest on
6. Interferences
6.1 Accurate reporting of observed failure modes is essen-
tial for meaningful data interpretation, in particular, the detec-
Boldface numbers in parentheses refer to the list of references at the end of this
standard. tion of initial damage modes.
D 2344/D 2344M
7.4 Conditioning Chamber, when conditioning materials at
nonlaboratory environments, a temperature/vapor-level-
controlledenvironmentalconditioningchamberisrequiredthat
shall be capable of maintaining the required temperature to
within 63°C (65°F) and the required vapor level to within
63 %. Chamber conditions shall be monitored either on an
automated continuous basis or on a manual basis at regular
intervals.
7.5 Environmental Test Chamber, an environmental test
chamber is required for test environments other than ambient
testing laboratory conditions. This chamber shall be capable of
maintaining the test specimen at the required test environment
during the mechanical test method.
8. Sampling and Test Specimens
8.1 Sampling—Test at least five specimens per test condi-
tion unless valid results can be gained through the use of fewer
specimens, as in the case of a designed experiment. For
statistically significant data, consult the procedures outlined in
Practice E 122. Report the method of sampling.
8.2 Geometry:
8.2.1 Laminate Configurations—Both multidirectional and
pure unidirectional laminates can be tested, provided that there
are at least 10 % 0° fibers in the span direction of the beam
(preferably well distributed through the thickness), and that the
laminates are both balanced and symmetric with respect to the
span direction of the beam.
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/
ASME B46.1-1986.
8.2.2 Specimen Configurations—Typical configurations for
NOTE 2—Ply orientation tolerance 60.5° relative to –B–.
the flat and curved specimens are shown in Figs. 1-4. For
FIG. 2 Flat Specimen Configuration (Inch Pound)
specimen thicknesses other than those shown, the following
geometries are recommended:
Specimen length = thickness 3 6
7. Apparatus
Specimen width, b = thickness 3 2.0
7.1 Testing Machine, properly calibrated, which can be
NOTE 2—Analysis reported by Lewis and Adams (6) has shown that a
operated at a constant rate of crosshead motion, and which the
width-to-thickness ratio of greater than 2.0 can result in a significant
error in the loading system shall not exceed 61 %. The
width-wise shear-stress variation.
load-indicating mechanism shall be essentially free of inertia
8.2.2.1 For curved beam specimens, it is recommended that
lag at the crosshead rate used. Inertia lag may not exceed 1 %
the arc should not exceed 30°. Also, for these specimens, the
ofthemeasuredload.Theaccuracyofthetestingmachineshall
specimen length is defined as the minimum chord length.
be verified in accordance with Practices E 4.
8.3 Specimen Preparation—Guide D 5687/D 5687M pro-
7.2 Loading Nose and Supports, as shown in Figs. 5 and 6,
vides recommended specimen preparation practices and should
shallbe6.00-mm(0.250-in.)and3.00-mm(0.125-in.)diameter
be followed where practical.
cylinders, respectively, with a hardness of 60 to 62 HRC, as
8.3.1 Laminate Fabrication—Laminates may be hand-laid,
specified in Test Methods E 18, and shall have finely ground
filament-wound or tow-placed, and molded by any suitable
surfaces free of indentation and burrs with all sharp edges
laminating means, such as press, bag, autoclave, or resin
relieved.
transfer molding.
7.3 Micrometers—For width and thickness measurements,
8.3.2 Machining Methods—Specimen preparation is impor-
the micrometers shall use a 4- to 5-mm (0.16- to 0.2-in.)
tant for these specimens. Take precautions when cutting
nominal diameter ball interface on an irregular surface such as
specimens from the rings or plates to avoid notches, undercuts,
thebagsideofalaminateandaflatanvilinterfaceonmachined
rough or uneven surfaces, or delaminations as a result of
edges or very smooth tooled surfaces.Amicrometer or caliper
inappropriate machining methods. Obtain final dimensions by
with flat anvil faces shall be used to measure the length of the
water-lubricated precision sawing, milling, or grinding. The
specimen. The accuracy of the instrument(s) shall be suitable
use of diamond tooling has been found to be extremely
forreadingtowithin1 %ofthesampledimensions.Fortypical
effective for many material systems. Edges should be flat and
section geometries, an instrument with an accuracy of 60.002
parallel within the specified tolerances.
mm (60.0001 in.) is desirable for thickness and width mea-
surement, while an instrument with an accuracy of 60.1 mm 8.3.3 Labeling—Label the specimens so that they will be
(60.004 in.) is adequate for length measurement. distinct from each other and traceable back to the raw material,
D 2344/D 2344M
NOTE 1—Drawing interpretation per ANSI Y14.5-1982 and ANSI/ASM B46.1-1986.
NOTE 2—Ply orientation tolerance 60.5° relative to –A–.
FIG. 3 Curved Specimen Configuration (SI)
in a manner that will both be unaffected by the test method and 11. Procedure
not influence the test method.
11.1 Parameters to Be Specified Before Test:
11.1.1 The specimen sampling method and coupon geom-
9. Calibration
etry.
9.1 The accuracy of all measuring equipment shall have
11.1.2 The material properties and data-reporting format
certified calibrations that are current at the time of use of the
desired.
equipment.
NOTE 3—Determine specific material property, accuracy, and data-
10. Conditioning
reporting requirements before test for proper selection of instrumentation
and data-recording equipment. Estimate operating stress levels to aid in
10.1 Standard Conditioning Procedure—Unless a different
calibration of equipment and determination of equipment settings.
environment is specified as part of the test method, condition
the test specimens in accordance with Procedure C of Test 11.1.3 The environmental conditioning test parameters.
Method D 5229/D 5229M, and store and test at standard 11.1.4 If performed, the sampling test me
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.