ASTM D4255/D4255M-83(1994)e1
(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
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.
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.
1.4 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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e1
Designation: D 4255/D 4255M – 83 (Reapproved 1994)
Standard Guide for Testing
In-plane Shear Properties of Composite Laminates
This standard is issued under the fixed designation D 4255/D 4255M; 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.
e NOTE—Section 12 was added and other editorial changes were made in December 1994.
1. Scope
1.1 The in-plane shear properties are determined by impos-
ing edgewise shear loads on the specimen using Method A, a
fixture consisting of two pairs of rails tensile loaded; or Method
B, a fixture consisting of three pairs of rails in tension or
compression loading.
1.2 Two methods are presented as follows:
1.2.1 Method A—Test of in-plane shear shall be made on
specimens clamped between two pairs of steel loading rails.
See Fig. 1. This fixture, when loaded in tension, introduces
shear forces in the specimen that produce failures across the
panel. With most composite sheet materials, failure is due to a
combination of diagonal tension and compression forces.
1.2.2 Method B—Test of in-plane shear shall be made on
specimens clamped securely on opposite edges and a load
applied to a third pair of steel rails in the center. See Fig. 2. The
center load of either tension or compression will produce a
shear load in each section of the specimen. With most
composite sheet materials, failure is due to a combination of
diagonal tension and compression forces.
NOTE 1—Strain gages at 645° have shown significantly different shear
strains on the same specimen. This may be due to differences in shear
behavior with a tensile force at one 45° angle and compression force at the
opposite 45° angle.
1.3 In-plane Shear—The shear associated with shear forces
applied to the edges of the laminate so that the resulting shear
deformations occur in the plane of the laminate rather than
FIG. 1 Method A Assembly Rail Shear Apparatus
through the thickness.
1.4 In-plane shear specimens normally fail by buckling out
shear properties of resin-matrix composites reinforced by
of plane. The measured values of ultimate shear strength and
continuous or discontinuous high-modulus, 20 GPa [3 3 10−6
shear modulus may be affected by sample dimensions or
psi] or greater, fibers. This includes the following:
physical constraints, or both, that cause the sample to resist this
1.5.1 Unidirectional—Continuous or discontinuous rein-
out-of-plane buckling. Because of the above, this method is a
forcing fibers, 0° and 90° properties.
standard guide instead of a standard method. Data obtained
1.5.2 Laminates of Symmetric, Orthotropic Construction
should be judged on this basis. For similar materials of the
(Note 2)—Continuous or discontinuous reinforcing fibers.
same sample dimensions in the same test system, consistent
results are possible.
NOTE 2—Difficulties may arise when using this method in conjunction
1.5 These methods cover the determination of the in-plane
with 6 45° angle-ply laminates. In particular, detailed stress analysis has
shown that a uniform state of shear is not attained for this orientation. Test
Method D 3518/D 3518M is recommended as an alternative.
This guide is under the jurisdiction of ASTM Committee D-30 on High
1.5.3 Random-oriented fibrous laminates.
Modulus Fibers and Their Composites and is the direct responsibility of Subcom-
1.6 This standard does not purport to address all of the
mittee D 30.04 on High-Performance Fibers and Composites.
safety concerns, if any, associated with its use. It is the
Current edition approved May 27, 1983. Published September 1983.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4255/D 4255M
bolts. A tensile force is applied to the rails which induces an
in-plane shear load on the specimen. If shear modulus is
required, a strain gage is mounted in the center of the specimen
at 45° to the specimen’s longitudinal axis. The load is applied
to failure. The failure strength, elastic shear strain, and failure
mode should be recorded. A typical two rail shear fixture is
shown in Figs. 1 and 3 with details in Figs. 4-6.
3.1.2 Method B—The test fixture consists of three pairs of
rails that are fastened to the test specimen usually by bolts. The
two outside pairs of rails are attached to a base plate which
rests on the test machine. A third pair of rails (middle rails) are
guided through a slot in the top of the base fixture. The unit
shown is loaded in compression. It would also be permissible
to tensile load the middle rails but this will require fastening
the base fixture to the test machine. If modulus values are
desired, the strain gage should be mounted in the center of both
test sections at 45° to the specimen’s longitudinal axis. The
load is applied to failure. The failure strength, elastic shear
strain, and failure mode should be recorded. A typical three rail
shear fixture is shown in Fig. 2, Fig. 7, and Fig. 8. Details are
shown in Figs. 9-11.
4. Significance and Use
4.1 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
properties and should therefore be reported are: material, fiber
orientation, fiber form (continuous or chopped), stacking
FIG. 2 Method B Assembly Rail Shear Fixture
sequence, methods of material and specimen preparation,
specimen conditioning, environment of testing, void content,
responsibility of the user of this standard to establish appro-
volume percent reinforcement, specimen dimensions, and test
priate safety and health practices and determine the applica-
method chosen.
bility of regulatory limitations prior to use.
1.7 The values stated in either SI or inch-pound units are to
5. Apparatus
be regarded separately as standard. Within the text the inch-
5.1 Gages, suitable for reading to within 1 % of the sample
pound units are shown in brackets. The values stated in each
length and thickness.
system are not exact equivalents; therefore each system must
5.2 Testing Machine, comprised of the following:
be used independently of the other. Combining values from the
5.2.1 Fixed Member—A fixed or essentially stationary
two systems may result in nonconformance with the standard.
member supporting the load fixture.
2. Referenced Documents
5.2.2 Movable Member, capable of applying a compressive
2.1 ASTM Standards: or tensile load to the test fixture.
5.2.3 Drive Mechanism—A drive for imparting to the mov-
D 618 Practice for Conditioning Plastics and Electrical
Insulating Materials for Testing able member a controlled velocity with respect to the stationary
member.
D 3518/D 3518M Test Method for In-Plane Shear Response
of Polymer Matrix Composite Materials by Tensile Test of 5.2.4 Load Indicator—A suitable load-indicating mecha-
nism shall be provided that is capable of showing the total
a 645° Laminate
E 4 Practices for Force Verification of Testing Machines compressive or tensile load carried by the test fixture. This
mechanism should indicate the load with an accuracy of 1 % or
E 83 Practice for Verification and Classification of Exten-
someters better of the true value. The accuracy of the testing machine
shall be verified in accordance with Practices E 4.
3. Summary of Methods
5.2.5 Strain Recording—A suitable strain-recording system
3.1 A flat rectangular plate is tested in a rail shear fixture as
is required for modulus determinations.
follows: 5.3 Rails—Rails are shown in Fig. 4, Fig. 9, Fig. 10, and
3.1.1 Method A—The test fixture consists of two pairs of
Fig. 11 for clamping the test specimen. Drilled holes should be
rails which can be fastened to the test specimen usually by oversized to prevent stress risers when the bolts are tightened.
Hole tolerances will depend on the material tested and gripping
methods.
Annual Book of ASTM Standards, Vol 08.01.
5.3.1 The following modifications have been used to grip
Annual Book of ASTM Standards, Vol 15.03.
Annual Book of ASTM Standards, Vol 03.01. the specimens:
D 4255/D 4255M
* Surface finish to specification
Dimension mm in. Dimension mm in.
A 60.1 2.38 H 3.2 0.125
B 15.9 0.625 I 9.5 0.375
C 22.2 0.875 J 6.5 0.25
D 209.6 8.25 K 28.6 1.125
E 25.0 1.0 L 12.7 0.50
F 51.0 2.0 M 47.6 1.875
G 19.0 0.75 N 9.7 0.38
FIG. 4 Rails for Method A
Detail Two Rail Shear Rails
Four Required Two This Way
Two Reversed
Not to Scale
D 4255/D 4255M
Dimension mm in.
Dimension mm in.
A 25 1 ⁄8
A 33.0 to 3.5 1 ⁄4 to 12
B 12 ⁄2
B 38.0 1 ⁄2
C 22 ⁄8
C 13.0 ⁄2
1 D 67 2 ⁄8
D 6.0 ⁄4
E 98 3 ⁄8
E 24.0 ⁄16
9 F 25 1
F 7.0 ⁄32
G 48 1 ⁄8
G 76.0 3
H 128.5 5 ⁄16
FIG. 6 Load Plate for Method A
I 41.3 1 ⁄8
Two Required—Cold-Rolled Steel
J 25.0 1
K 51.0 2
specimen usually by bolts. The rails are then attached to the test
FIG. 5 Tensile Head for Method A
machine through pins, a plate that acts as an aligning fixture,
Two Required—Cold-Rolled Steel
and a clevis that connects directly to the test machine. This
5.3.1.1 Abrasive paper or cloth adhered to the rails, equipment is typical but not the only configuration usable.
5.3.1.2 Machining V grooves in the rails, Note that earlier tests have been run where the two rail shear
5.3.1.3 Center punching rails in random order, fixtures were compression loaded. Also see 5.3.1 for rail
5.3.1.4 Changing number of bolt holes from three up to modifications.
eight per rail associated with smaller holes, 5.4.2 Method B—A typical three-rail shear fixture is shown
5.3.1.5 Soft metal shims, and in Fig. 2, Fig. 7, and Fig. 8. Details are shown in Figs. 9-11.
5.3.1.6 Tabbing specimens in rail areas. The test fixture consists of three pairs of rails that are fastened
5.3.2 The above list is not inclusive but was typical of to the test specimen usually by bolts. The two outside pairs of
methods used by various laboratories to meet the requirements rails are attached to a base plate that rests on the test machine.
of specific materials. Items that work for one material may be
The third pair of rails (middle rails) are guided through a slot
unacceptable for another. If these modifications are to be used in the top of the base fixture. The unit shown is loaded in
as part of a specification, it is important that the rail grip system
compression. It would also be permissible to tensile load the
be completely specified and these modifications noted in the middle rails, but this will require fastening the base fixture to
test report. the test machine. This equipment is typical but not the only
5.4 Test Fixtures: configuration that is usable. Also see 5.3.1 for rail modifica-
5.4.1 Method A—A typical two-rail shear fixture is shown in tions.
Fig. 1 and Fig. 3 with details in Figs. 4-6. The test fixture 5.5 Strain—Where load-strain data are desired, the speci-
consists of two pairs of rails which can be fastened to the test men may be instrumented with strain gages.
D 4255/D 4255M
be supported by rails dimensioned in Fig. 4. Note that while the
sample outer dimensions are uniform, many variations of hole
patterns and tabbed edges have been used. See 5.3.1.
NOTE 4—It is recommended that laminates be 1.27 to 3.17 mm [0.050
to 0.125 in.] thick. Thin laminates tend to exhibit buckling at low loads
while thicker laminates can have shear strengths in excess of the
rail-clamping capacity.
6.1.2 Method B—The test specimen shall conform to the
dimensions shown in Fig. 13 (Note 4) and shall be supported
by rails dimensioned in Figs. 9-11.
6.2 The straight edges of the specimen may have coarse tool
marks from the machining operation; however, the holes
should be drilled and reamed if minor delamination occurs.
The holes shown are oversize to the bolts, although press fit
bolts have been used with success, particularly with tabbed
specimens.
6.3 Number of Specimens—At least five specimens shall be
tested for each sample.
6.4 Health and Safety—When fabricating composite speci-
mens by machining operations, a fine dust consisting of
particles of fibers or the matrix material, or both, may be
formed. These fine dusts can be a serious health or safety, or
both, hazard. Adequate protection should be afforded operating
personnel and equipment. This may require adequate ventila-
tion or dust collecting, or both, facilities at a minimum.
7. Conditioning
7.1 Standard Conditioning Procedure—The test specimen
shall be conditioned and tested in a room or enclosed space
maintained at 23 6 2°C [73.4 6 3.6°F] and 50 6 5 % relative
humidity in accordance with Procedure A of Practice D 618.
FIG. 7 Method B Assembled Typical Test Fixture
8. Procedure
5.5.1 Location—The strain gages should be located at the
8.1 Method A:
center of the specimen at a 45° angle to the rails as illustrated
8.1.1 Speed of Testing, shall be determined by the specifi-
in Fig. 1 and Fig. 6. The gages, surface preparation, and
cations for the material being tested or by agreement between
bonding agents should be chosen to provide for adequate
those concerned. However, when the speed of testing is not
performance on the subject material, and suitable automatic-
specified, a speed of 1 to 1.5 mm/min [0.04 to 0.06 in./min]
strain recording equipment shall be employed. Some laborato-
should be used.
ries have found it necessary to reduce the rail size in the
8.1.2 Measure the least length between the rails to the
strain-gage area to have sufficient space for the strain gages and
nearest 0.25 mm [0.01 in.] and several thicknesses along the
wire leads.
length of the specimen to the nearest 0.025 mm [0.001 in.].
5.5.2 For initial trials of the equipment, modification of
Record the minimum cross-sectional area.
equipment, or a new material, it is recommended that strain
8.1.3 Place the specimen between the pairs of rails. Align
rosettes of 0 and 645° be used. Using this method, it is
the rails with the specimen. Place a 12.5-mm [ ⁄2-in.] spacer
possible to see if the major shear strains are at 645° and if they
between opposite pairs of rails. Ensure that there is no bearing
are equal. If the major shear strains are not at 645°, it is
contact, in the direction of loading, between the 9.5-mm
possible to rotate the strains with use of the 0° data. Equations 3 1
[ ⁄8-in.] diameter bolts and the 12.5-mm [ ⁄2-in.] diameter holes.
to rotate strains are available from several references, including
Orient the rail guides and apply a torque of 7 to 70 N·m [5 to
most strain-gage manufacturers li
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