ASTM C1292-00
(Test Method)Standard Test Method for Shear Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures
Standard Test Method for Shear Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures
SCOPE
1.1 This test method covers the determination of shear strength of continuous fiber-reinforced ceramic composites (CFCCs) at ambient temperature. The test methods addressed are (1) the compression of a double-notched specimen to determine interlaminar shear strength and (2) the Iosipescu test method to determine the shear strength in any one of the material planes of laminated composites. Specimen fabrication methods, testing modes (load or displacement control), testing rates (load rate or displacement rate), data collection, and reporting procedures are addressed.
1.2 This test method is used for testing advanced ceramic or glass matrix composites with continuous fiber reinforcement having uni-directional (1-D) or bi-directional (2-D) fiber architecture. This test method does not address composites with (3-D) fiber architecture or discontinous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics.
1.3 The values stated in SI units are to be regarded as the standard and are in accordance with Practice E380.
1.4 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. Specific hazard statements are given in 8.1 and 8.2.
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Designation:C 1292–00
Standard Test Method for
Shear Strength of Continuous Fiber-Reinforced Advanced
Ceramics at Ambient Temperatures
This standard is issued under the fixed designation C 1292; 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 D 3878 Terminology for High-Modulus Reinforcing Fibers
and Their Composites
1.1 This test method covers the determination of shear
D 5379/D 5379M Test Method for Shear Properties of
strength of continuous fiber-reinforced ceramic composites
Composite Materials by the V-Notched Beam Method
(CFCCs) at ambient temperature. The test methods addressed
E 4 Practices for Force Verification of Testing Machines
are (1) the compression of a double-notched specimen to
E 6 Terminology Relating to Methods of Mechanical Test-
determine interlaminar shear strength and (2) the Iosipescu test
ing
method to determine the shear strength in any one of the
E 122 Practice for Choice of Sample Size to Estimate a
material planes of laminated composites. Specimen fabrication
Measure of Quality for a Lot or Process
methods, testing modes (load or displacement control), testing
E 177 Practice for Use of the Terms Precision and Bias in
rates (load rate or displacement rate), data collection, and
ASTM Test Methods
reporting procedures are addressed.
E 337 Test Method for Measuring Humidity with Psy-
1.2 This test method is used for testing advanced ceramic or
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
glass matrix composites with continuous fiber reinforcement
peratures)
having uni-directional (1-D) or bi-directional (2-D) fiber archi-
E 380 Practice for Use of International System of Units
tecture. This test method does not address composites with
(SI)
(3-D) fiber architecture or discontinous fiber-reinforced,
E 691 Practice for Conducting an Interlaboratory Study to
whisker-reinforced, or particulate-reinforced ceramics.
Determine the Precision of a Test Method
1.3 The values stated in SI units are to be regarded as the
standard and are in accordance with Practice E 380.
3. Terminology
1.4 This standard does not purport to address all of the
3.1 Definitions—The definitions of terms relating to shear
safety concerns, if any, associated with its use. It is the
strength testing appearing in Terminology E 6 apply to the
responsibility of the user of this standard to establish appro-
terms used in this test method.The definitions of terms relating
priate safety and health practices and determine the applica-
to advanced ceramics appearing in Terminology C 1145 apply
bility of regulatory limitations prior to use. Specific hazard
to the terms used in this test method. The definitions of terms
statements are given in 8.1 and 8.2.
relating to fiber-reinforced composites appearing in Terminol-
2. Referenced Documents ogy D 3878 apply to the terms used in this test method.
Additional terms used in conjunction with this test method are
2.1 ASTM Standards:
defined in the following.
C 1145 Terminology of Advanced Ceramics
3.1.1 advanced ceramic—an engineered high-performance
D 695 Test Method for Compressive Properties of Rigid
predominately nonmetallic, inorganic, ceramic material having
Plastics
specific functional attributes.
D 3846 Test Method for In-Plane Shear Strength of Rein-
3.1.2 continuous fiber-reinforced ceramic matrix composite
forced Plastics
(CFCC)—a ceramic matrix composite in which the reinforcing
phase consists of a continuous fiber, continuous yarn, or a
This test method is under the jurisdiction of ASTM Committee C-28 on woven fabric.
Advanced Ceramics and is the direct responsibility of Subcommittee C28.07 on
Ceramic Matrix Composites.
Current edition approved April 10, 2000. Published July 2000. Originally
published as C 1292 – 95. Last previous edition C 1292 – 95a. Annual Book of ASTM Standards, Vol 15.03.
2 6
Annual Book of ASTM Standards, Vol 15.01. Annual Book of ASTM Standards, Vol 03.01.
3 7
Annual Book of ASTM Standards, Vol 08.01. Annual Book of ASTM Standards, Vol 14.02.
4 8
Annual Book of ASTM Standards, Vol 08.02. Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1292
3.1.3 shear failure load—the maximum load required to
fracture a shear loaded test specimen.
3.1.4 shear strength—the maximum shear stress that a
material is capable of sustaining. Shear strength is calculated
from the shear fracture load and the shear loaded area.
4. Summary of Test Method
4.1 This test method addresses two methods to determine
the shear strength of CFCCs: (1) the compression of a
double-notched specimen test method to determine interlami-
nar shear strength and (2) the Iosipescu test method to
determine the shear strength in any one of the material planes
of laminated CFCCs.
4.1.1 Shear Test by Compression Loading of Double-
Notched Specimens—The interlaminar shear strength of
CFCCs, as determined by this method is measured by loading
in compression a double-notched specimen of uniform width.
Failure of the specimen occurs by shear between two centrally
located notches machined halfway through the thickness and
spaced a fixed distance apart on opposing faces. Schematics of
the test setup and the specimen are shown in Fig. 1 and Fig. 2.
4.1.2 Shear Test By the Iosipescu Method—The shear
strength of one of the different material shear planes of
laminated CFCCs may be determined by loading a coupon in
the form of a rectangular flat strip with symmetric centrally
located V-notches using a mechanical testing machine and a
four-point asymmetric fixture. The loading can be idealized as
asymmetric flexure by the shear and bending diagrams in Fig.
3. Failure of the specimen occurs by shear between the
V-notches. Different specimen configurations are addressed for
this test method. Schematics of the test setup and specimen are
shown in Fig. 4 and Fig. 5. The determination of shear
NOTE 1—All tolerances are in millimetres.
FIG. 2 Schematic of Double-Notched Compression Specimen
Whitney, J., M., “Stress Analysis of the Double Notch Shear Specimen,”
Proceedings of the American Society for Composites, 4th Technical Conference,
properties of polymer matrix composites by the Iosipescu
Blacksburg Virginia, Oct. 3–5, 1989, Technomic Publishing Co, pp. 325.
method has been presented in Test Method D 5379.
Iosipescu, N., “NewAccurate Procedure for ShearTesting of Metals,”Journal
of Materials, 2, 3, Sept. 1967, pp. 537–566.
5. Significance and Use
5.1 Continuous fiber-reinforced ceramic composites are
candidate materials for structural applications requiring high
degrees of wear and corrosion resistance, and damage toler-
ance at high temperatures.
5.2 Shear tests provide information on the strength and
deformation of materials under shear stresses.
5.3 This test method may be used for material development,
material comparison, quality assurance, characterization, and
design data generation.
5.4 For quality control purposes, results derived from stan-
dardized shear test specimens may be considered indicative of
the response of the material from which they were taken for
given primary processing conditions and post-processing heat
treatments.
6. Interferences
6.1 Test environment (vacuum, inert gas, ambient air, etc.)
including moisture content (for example, relative humidity)
FIG. 1 Schematic of Test Fixture for the Double-Notched
Compression Specimen may have an influence on the measured shear strength. In
C 1292
NOTE 1—The loads are depicted as being concentrated, whereas they
are actually distributed over an area.
FIG. 3 Idealized Force, Shear, and Moment Diagrams for
Asymmetric Four-Point Loading
NOTE 1—All tolerances are in millimetres.
FIG. 5 Schematic of the Iosipescu Specimen
slow crack growth effects. Conversely, testing can be con-
ducted in environments and testing modes and rates represen-
tative of service conditions to evaluate material performance
under those conditions. When testing is conducted in uncon-
trolled ambient air with the intent of evaluating maximum
strength potential, relative humidity and temperature must be
monitored and reported. Testing at humidity levels >65 % RH
is not recommended and any deviations from this recommen-
dation must be reported.
6.2 Preparation of test specimens, although normally not
considered a major concern with CFCCs, can introduce fabri-
cation flaws which may have pronounced effects on the
mechanical properties and behavior (for example, shape and
level of the resulting load-displacement curve and shear
strength). Machining damage introduced during specimen
preparation can be either a random interfering factor in the
determination of shear strength of pristine material, or an
inherent part of the strength characteristics to be measured.
Universal or standardized test methods of surface preparation
FIG. 4 Schematic of Test Fixture for the Iosipescu Test
do not exist. Final machining steps may, or may not negate
machining damage introduced during the initial machining.
particular, the behavior of materials susceptible to slow crack Thus, specimen fabrication history may play an important role
growthfracturewillbestronglyinfluencedbytestenvironment in the measured strength distributions and shall be reported.
and testing rate. Testing to evaluate the maximum strength 6.3 Bending in uniaxially loaded shear tests can cause or
potential of a material shall be conducted in inert environments promote nonuniform stress distributions that may alter the
or at sufficiently rapid testing rates, or both, so as to minimize desired uniform state of stress during the test.
C 1292
6.4 Fractures that initiate outside the uniformly stressed element that attaches to the crosshead of the testing machine,
gage section of a specimen may be due to factors such as and two jaws to fix the specimen in position. A schematic
localized stress concentrations, extraneous stresses introduced description of the test fixture is shown in Fig. 1. Asupporting
by improper loading configurations, or strength-limiting fea- jig conforming to the geometry of that shown in Fig. 1 of Test
tures in the microstructure of the specimen. Such non-gage Method D 3846 or Fig. 4 of Test Method D 695 may also be
section fractures will normally constitute invalid tests. used.
6.5 For the conduction of the Iosipescu test, thin test 7.4.2 Iosipescu Specimen—The fixture shall be a four-point
specimens (width to thickness ratio of more than ten) may asymmetric flexure fixture shown schematically in Fig.
suffer from splitting and instabilities rendering in turn invalid 4. This fixture consists of a stationary element mounted on a
test results. base plate, and a movable element capable of vertical transla-
6.6 For the evaluation of the interlaminar shear strength by tion guided by a stiff post.The movable element attaches to the
the compression of a double-notched specimen, the distance cross-head of the testing machine. Each element clamps half of
between the notches in the specimen has an effect on the the test specimen into position with a wedge action grip able to
maximum load and therefore on the shear strength. It has been compensate for minor specimen width variations.Aspan of 13
foundthatthestressdistributioninthespecimenisindependent mm is left unsupported between fixture halves. An alignment
of the distance between the notches when the notches are far tool is recommended to ensure that the specimen notch is
apart. However, when the distance between the notches is such aligned with the line-of-action of the loading fixture.
that the stress fields around the notches interact, the measured
8. Hazards
interlaminar shear strength increases. Because of the complex-
ity of the stress field around each notch and its dependence on
8.1 During the conduct of this test method, the possibility of
the properties and homogeneity of the material, it is recom- flying fragments of broken test material may be high. The
mended to conduct a series of tests on specimens with different
brittle nature of advanced ceramics and the release of strain
spacing between the notches to determine their effect on the energy contribute to the potential release of uncontrolled
measured interlaminar shear strength.
fragments upon fracture. Means for containment and retention
6.7 For the evaluation of the interlaminar shear strength by of these fragments for later fractographic reconstruction and
the compression of a double-notched specimen, excessive
analysis is highly recommended.
clamping force with the jaws will reduce the stress concentra- 8.2 Exposed fibers at the edges of CFCC specimens present
tion around the notches and therefore artificially increase the
a hazard due to the sharpness and brittleness of the ceramic
measured interlaminar shear strength. Because the purpose of fiber. All persons required to handle these materials shall be
the jaws is to maintain the specimen in place and to prevent
well informed of these conditions and the proper handling
buckling, avoid overtightening the jaws. techniques.
6.8 Most fixtures incorporate an alignment mechanism in
9. Test Specimens
the form of a guide rod and a linear roller bearing. Excessive
freeplayorexcessivefrictioninthismechanismmayintroduce
9.1 Test Specimen Geometry:
spurious moments that will alter the ideal loading conditions.
9.1.1 Double-Notched Compression Specimen—The test
specimens shall conform to the shape and tolerances shown in
7. Apparatus
Fig. 2. The specimen consists of a rectangular plate with
7.1 Testing Machines—The testing machine shall be in
notches machined on both sides.The depth of the notches shall
conformancewithPracticesE 4.Theloadsusedindetermining
be at least equal to one half of the specimen thickness, and the
shearstrengthshallbeaccuratewithin 61 %atanyloadwithin
distance between the notches shall be determined considering
the selected load range of the testing machine as defined in
the requirements to produce shear failure in the gage section.
Practices E 4.
Furthermore, because the measured interlaminar shear strength
7.2 Data Acquisition—At the minimum, autographic
may be dependent on the notch separation, it is recommended
records of applied load and cross-head displacement versus
to conduct tests with different values of notch separation to
time shall be obtained. Either analog chart recorders or digital
determine this dependence. The e
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