ASTM D4255/D4255M-01(2007)
(Guide)Standard Test Method for In-Plane Shear Properties of Polymer Matrix Composite Materials by the Rail Shear Method
Standard Test Method for In-Plane Shear Properties of Polymer Matrix Composite Materials by the Rail Shear Method
SIGNIFICANCE AND USE
These shear tests are designed to produce in-plane shear property data for material specifications, research and development, and design. Factors that influence the shear response and should therefore be reported include: 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 fiber volume reinforcement content. Properties that may be measured by this test method include:
5.1.1 In-plane shear stress versus shear strain response,
5.1.2 In-plane shear chord modulus of elasticity,
5.1.3 Offset shear stress, and
5.1.4 Maximum in-plane shear stress. In cases in which the strain at failure is greater than 5 %, the shear stress corresponding to 5 % shear strain should be reported.
SCOPE
1.1 This test method determines the in-plane shear properties of high-modulus fiber-reinforced composite materials by either of two procedures. In Procedure A, laminates clamped between two pairs of loading rails are tested. When loaded in tension the rails introduce shear forces in the specimen. In Procedure B, laminates clamped on opposite edges with a tensile or compressive load applied to a third pair of rails in the center are tested.
1.2 Application of this test method is limited to continuous-fiber or discontinuous-fiber-reinforced polymer matrix composites in the following material forms:
1.2.1 Laminates composed only of unidirectional fibrous laminae, with the fiber direction oriented either parallel or perpendicular to the fixture rails.
1.2.2 Laminates composed only of woven fabric filamentary laminae with the warp direction oriented either parallel or perpendicular to the fixture rails.
1.2.3 Laminates of balanced and symmetric construction, with the 0 direction oriented either parallel or perpendicular to the fixture rails.
1.2.4 Short-fiber-reinforced composites with a majority of the fibers being randomly distributed.Note 1
Additional test methods for determining in-plane shear properties of polymer matrix composites may be found in Test Methods D 5379/D 5379M and D 5448/D 5448M, and Practice D 3518/D 3518M.
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. Within the text the inch-pounds 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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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
Designation: D4255/D4255M − 01(Reapproved 2007)
Standard Test Method for
In-Plane Shear Properties of Polymer Matrix Composite
Materials by the Rail Shear Method
This standard is issued under the fixed designation D4255/D4255M; 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 each system are not exact equivalents; therefore, each system
must be used independently of the other. Combining values
1.1 This test method determines the in-plane shear proper-
from the two systems may result in nonconformance with the
ties of high-modulus fiber-reinforced composite materials by
standard.
either of two procedures. In Procedure A, laminates clamped
between two pairs of loading rails are tested. When loaded in
2. Referenced Documents
tension the rails introduce shear forces in the specimen. In
2.1 ASTM Standards:
Procedure B, laminates clamped on opposite edges with a
D792 Test Methods for Density and Specific Gravity (Rela-
tensile or compressive load applied to a third pair of rails in the
tive Density) of Plastics by Displacement
center are tested.
D883 Terminology Relating to Plastics
1.2 Application of this test method is limited to continuous-
D2584 Test Method for Ignition Loss of Cured Reinforced
fiber or discontinuous-fiber-reinforced polymer matrix com-
Resins
posites in the following material forms:
D2734 TestMethodsforVoidContentofReinforcedPlastics
1.2.1 Laminates composed only of unidirectional fibrous
D3171 Test Methods for Constituent Content of Composite
laminae, with the fiber direction oriented either parallel or
Materials
perpendicular to the fixture rails.
D3518/D3518M Test Method for In-Plane Shear Response
1.2.2 Laminatescomposedonlyofwovenfabricfilamentary
of Polymer Matrix Composite Materials byTensileTest of
laminae with the warp direction oriented either parallel or
a 645° Laminate
perpendicular to the fixture rails.
D3878 Terminology for Composite Materials
1.2.3 Laminates of balanced and symmetric construction,
D5229/D5229M Test Method for MoistureAbsorption Prop-
withthe0°directionorientedeitherparallelorperpendicularto
erties and Equilibrium Conditioning of Polymer Matrix
the fixture rails.
Composite Materials
1.2.4 Short-fiber-reinforced composites with a majority of
D5379/D5379M Test Method for Shear Properties of Com-
the fibers being randomly distributed.
posite Materials by the V-Notched Beam Method
D5448/D5448M Test Method for Inplane Shear Properties
NOTE 1—Additional test methods for determining in-plane shear
properties of polymer matrix composites may be found in Test Methods
of Hoop Wound Polymer Matrix Composite Cylinders
D5379/D5379M and D5448/D5448M, and Practice D3518/D3518M.
E4 Practices for Force Verification of Testing Machines
1.3 This standard does not purport to address all of the
E6 Terminology Relating to Methods of Mechanical Testing
safety concerns, if any, associated with its use. It is the E111 Test Method for Young’s Modulus, Tangent Modulus,
responsibility of the user of this standard to establish appro-
and Chord Modulus
priate safety and health practices and determine the applica- E122 Practice for Calculating Sample Size to Estimate,With
bility of regulatory limitations prior to use.
Specified Precision, the Average for a Characteristic of a
1.4 The values stated in either SI units or inch-pound units Lot or Process
are to be regarded separately as standard. Within the text the
E177 Practice for Use of the Terms Precision and Bias in
inch-pounds units are shown in brackets. The values stated in ASTM Test Methods
E251 Test Methods for Performance Characteristics of Me-
tallic Bonded Resistance Strain Gages
This test method is under the jurisdiction of ASTM Committee D30 on
Composite Materials and is the direct responsibility of Subcommittee D30.04 on
Lamina and Laminate Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2007. Published June 2007. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1983. Last previous edition approved in 2001 as D4255/D4255M – 01. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D4255_D4255M-01R07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4255/D4255M − 01 (2007)
to analytical dimensions when used with square brackets, as the symbols
E456 Terminology Relating to Quality and Statistics
may have other definitions when used without the brackets.
E1237 Guide for Installing Bonded Resistance Strain Gages
E1309 Guide for Identification of Fiber-Reinforced 3.2 Definitions of Terms Specific to This Standard:
Polymer-Matrix Composite Materials in Databases 3.2.1 in-plane shear, n—shear associated with shear forces
E1434 Guide for Recording Mechanical Test Data of Fiber- applied to the edges of the laminate so that the resulting shear
Reinforced Composite Materials in Databases deformations occur in the plane of the laminate rather than
E1471 Guide for Identification of Fibers, Fillers, and Core through the thickness.
Materials in Computerized Material Property Databases
3.2.2 offset shear stress [M/(LT )] ,n—the shear stress
2.2 ASTM Adjunct:
associated with an offset of the shear chord modulus of
Adjunct No. ADJD4255, Rail Shear Fixtures Machining
elasticity line along the strain axis (see 12.4).
Drawings
3.2.3 shear strength [M/(LT )],n—the shear stress carried
by a material at failure under a pure shear condition.
3. Terminology
3.2.4 transition region, n—a strain region of a stress-strain
3.1 Terminology D3878 defines terms relating to high-
or strain-strain curve over which a significant change in the
modulus fibers and their composites. Terminology D883 de-
slope of the curve occurs within a small strain range.
fines terms relating to plastics. Terminology E6 defines terms
3.2.4.1 Discussion—Many filamentary composite materials
relating to mechanical testing. Terminology E456 and Practice
exhibit a nonlinear response during loading, such as seen in
E177 define terms relating to statistics. In the event of a
plots of either longitudinal stress versus longitudinal strain or
conflict between terms, Terminology D3878 shall have prece-
transverse strain versus longitudinal strain. In certain cases, the
dence over the other terminology standards.
nonlinear response may be conveniently approximated by a
NOTE 2—If the term represents a physical quantity, its analytical
bilinear fit.There are several physical reasons for the existence
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
of a transition region. Common examples include matrix
fundamental dimension form, using the following ASTM standard sym-
cracking under tensile loading and ply delamination.
bology for fundamental dimensions, shown within square brackets: [M]
for mass, [L] for length, [T] for time, [θ] for thermodynamic temperature,
3.2.5 traveler, n—a small piece of the same material as, and
and [nd] for nondimensional quantities. Use of these symbols is restricted
processed similarly to, the test specimen, used for example to
measure moisture content as a result of conditioning. This is
3 also sometimes termed as a reference sample.
A copy of the detailed drawing for the construction of the fixtures shown in
Figs. 1 and 2 is available at a nominal cost from ASTM Headquarters. Request
3.3 Symbols: A = cross-sectional area of test specimen
Adjunct No. ADJD4255.
B = percent bending of specimen
y
CV = coefficient of variation statistic of a sample population
for a given property, %
o
F = offset shear stress, the value of the shear stress at the
intersection of the stress-strain plot with a line passing through
the offset strain value at zero stress and with a slope equal to
the shear chord modulus of elasticity
u
F = ultimate shear stress
G = shear modulus of elasticity
h = specimen thickness
l = specimen length, the dimension parallel to the rails in the
gage section
n = number of specimens
P = load carried by test specimen at ith data point
i
max
P = loadcarriedbyatestspecimenthatisthelesserof(1)
the maximum load before failure, (2) the load at 5 % shear
strain, or (3) the load at the bending limit (see 11.8.1)
s = sample standard deviation
n–1
x = measuredorderivedpropertyforanindividualspecimen
i
from the sample population
χ¯ = sample mean (average)
γ = shear strain
ε = indicated normal strain from strain transducer
-6 -6
µε=10 m/m (10 in./in.)
τ = shear stress at ith data point
i
4. Summary of Test Method
4.1 Procedure A: Two-Rail Shear Test—A flat panel with
FIG. 1 Procedure A Assembly Rail Shear Apparatus holes along opposing edges is clamped, usually by through
D4255/D4255M − 01 (2007)
FIG. 2 Procedure A Partially Assembled Typical Test Fixture
bolts,betweentwopairsofparallelsteelloadingrails,seeFigs.
1 and 2. When loaded in tension, this fixture introduces shear
forces in the specimen that produce failures across the panel.
This test method is typical but not the only configuration
usable. The two-rail shear fixtures can also be compression
loaded. The load may be applied to failure.
4.1.1 If load-strain data are required, the specimen may be
instrumented with strain gages. Two three-element strain gage
rosettes are installed at corresponding locations on both faces
of the specimen.
4.2 Procedure B: Three-Rail Shear Test—A flat panel,
clamped securely between pairs of rails on opposite edges and
initscenter,isloadedbysupportingthesiderailswhileloading
the center rails. See Figs. 3-5.Aload on the center rail of either
tensionorcompressionproducesashearloadineachsectionof
the specimen. The load may be applied to failure.
4.2.1 The test fixture consists of three pairs of parallel rails
usually bolted to the test specimen by through bolts. The two
outside pairs of rails are attached to a base plate which rests on
the test machine. A third pair (middle rails) is guided through
a slot in the top of the base fixture.The unit is normally loaded
in compression. It is also permissible to load the middle rails in
tension, but this requires attaching the base fixture to the test
machine.
4.2.2 If load-strain data are required, the specimen may be
instrumented with strain gages. Three-element strain gage
rosettes are to be installed at corresponding locations on
FIG. 3 Procedure B Assembly Rail Shear Fixture
opposite faces of the specimen.
4.3 Detailed fixture drawings are available as ASTM Ad-
junct No. ADJD4255.
ronment of testing, specimen alignment and gripping, speed of
5. Significance and Use
testing, time at temperature, void content, and fiber volume
5.1 These shear tests are designed to produce in-plane shear
reinforcement content. Properties that may be measured by this
property data for material specifications, research and
test method include:
development, and design. Factors that influence the shear
5.1.1 In-plane shear stress versus shear strain response,
response and should therefore be reported include: material,
5.1.2 In-plane shear chord modulus of elasticity,
methods of material preparation and lay-up, specimen stacking
sequence, specimen preparation, specimen conditioning, envi- 5.1.3 Offset shear stress, and
D4255/D4255M − 01 (2007)
influenced by specimen buckling. Failure by buckling should
not be interpreted as indicating the maximum shear strength.
6.3.1 Ply delamination is another possible failure mode for
laminates containing a large number of 45° plies. This failure
reflects instability of 45° plies loaded in compression as
contrasted to the overall buckling failure previously described.
Differences in strain gage readings will not be noticeable, but
the failure can be identified by delaminated plies in contrast to
fiber breakage.
6.4 Gripping—Failure through bolt holes indicates inad-
equate gripping. Alternate gripping methods are discussed in
7.2.3.
6.5 End Effects—This test method assumes a state of pure
shear throughout the length of the specimen gage section.
However, the gage section ends have zero shear stress because
no traction and no constraints are applied there. A stress
transition region exists between the ends and interior portions
of the gage section. The length of this transition region
determines the error induced in the material shear data.
7. Apparatus
7.1 Micrometers—The micrometer(s) shall use a suitable
size diameter ball interface on irregular surfaces such as the
bag-side of a laminate and a flat anvil interface on machined
edges or very-smooth tooled surfaces. The accuracy of the
instruments shall be suitable for reading to within 1 % of the
sample length and thickness. For typical specimen geometries,
an instrument with an accuracy of 62.5 µm [60.0001 in.] is
desirable for thickness measurement, while an instrument with
an accuracy of 625 µm [60.001 in.] is desirable for length
measurement.
FIG. 4 Procedure B Assembled Typical Test Fixture
7.2 Rail Shear Fixtures
7.2.1 Two-Rail Shear—A two-rail shear fixture is shown in
5.1.4 Maximum in-plane shear stress. In cases in which the
Figs. 1 and 2. Detailed fixture drawings are available asASTM
strainatfailureisgreaterthan5 %,theshearstresscorrespond-
Adjunct No. ADJD4255. The test fixture consists of two pairs
ing to 5 % shear strain should be reported.
of rails which can clamp the test specimen with through bolts.
The rails are then attached to the test machine through pins, a
6. Interferences
load plate that also aligns the rails with each other, and a clevis
6.1 Therearenostandardtestmethodscapableofproducing
that connects directly to the test machine. This equipment is
a perfectly pure and uniform shear stress condition to failure
typical but not the only configuration usable. The two-rail
for every material, although some test methods can come
shear fixture can be compression loaded.Also see 7.2.3 for rail
acceptably close for a specific material for a given engineering
modifications.
purpose. The off-axis load of the two-rail method introduces a
7.2.2 Three-Rail Shear—A three-rail shear fixture is shown
comparatively small tensile load in the panel.
in Figs. 3-5. Detailed fixture drawings are available as ASTM
Adjunct ADJD4255. The test fixture consists of three pairs of
6.2 Material and Specimen Preparation—Poormaterialfab-
rails that clamp the test specimen with through bolts.
...
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