ASTM C1292-22

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: C1292 − 16 C1292 − 22
Standard Test Method for
Shear Strength of Continuous Fiber-Reinforced Advanced
Ceramics at Ambient Temperatures
This standard is issued under the fixed designation C1292; 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.
1. 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 test 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. Test 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)unidirectional (1D) or bidirectional (2D) fiber architecture. This test method does not
address composites with (3-D)3D fiber architecture or discontinuous 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 IEEE/ASTM SI 10.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific hazard statements are given in 8.1 and 8.2.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C1145 Terminology of Advanced Ceramics
D695 Test Method for Compressive Properties of Rigid Plastics
D3846 Test Method for In-Plane Shear Strength of Reinforced Plastics
D3878 Terminology for Composite Materials
D5379/D5379M Test Method for Shear Properties of Composite Materials by the V-Notched Beam Method
E4 Practices for Force Calibration and Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
This test method is under the jurisdiction of ASTM Committee C28 on Advanced Ceramics and is the direct responsibility of Subcommittee C28.07 on Ceramic Matrix
Composites.
Current edition approved Jan. 15, 2016Feb. 1, 2022. Published February 2016February 2022. Originally approved in 1995. Last previous edition approved in 20102016
as C1292 – 10.C1292 – 16. DOI: 10.1520/C1292-16.10.1520/C1292-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1292 − 22
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E337 Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
IEEE/ASTM SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric
SystemMetric Practice
3. Terminology
3.1 Definitions:
3.1.1 The definitions of terms relating to shear strength testing appearing in Terminology E6 apply to the terms used in this test
method. The definitions of terms relating to advanced ceramics appearing in Terminology C1145 apply to the terms used in this
test method. The definitions of terms relating to fiber-reinforced composites appearing in Terminology D3878 apply to the terms
used in this test method. Additional terms used in conjunction with this test method are defined in the following.
3.1.2 advanced ceramic—engineered high-performance a highly engineered, high-performance, predominately nonmetallic,
inorganic, ceramic material having specific functional attributes.
3.1.3 continuous fiber-reinforced ceramic matrix composite (CFCC)—a ceramic matrix composite in which the reinforcing
phasephase(s) consists of a continuous fiber, continuousfilaments, fibers, yarn, braid, or a knitted or woven fabric.
3.1.4 shear breaking force (F)—maximum force required to fracture a shear-loaded test specimen.
3.1.5 shear strength (F/L )—maximum shear stress that a material is capable of sustaining. Shear strength is calculated from
breaking force in shear and shear area.
4. Summary of Test Method
4.1 This test method addresses two methods to determine the shear strength of CFCCs: (1) the compression test method to
determine interlaminar shear strength of a double-notched test specimen, 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 Test Specimens—The interlaminar shear strength of CFCCs, as
determined by this method, is measured by compressively loading in compression a double-notched test specimen of uniform
width. Failure of the test specimen occurs by shear between two centrally located notches notch tips machined halfway through
the thickness and spaced a fixed distance apart on opposing faces. Schematics of the test setup and the test specimen are shown
in Fig. 1Figs. 1 and 2 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 test specimen 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 test specimen occurs by shear between the V-notches. Different test
specimen configurations are addressed for this test method. Schematics of the test setup and test specimen are shown in Fig. 4Figs.
4 and 5 and Fig. 5. The determination of shear properties of polymer matrix composites by the Iosipescu method has been presented
in Test Method D5379/D5379M.
5. Significance and Use
5.1 Continuous fiber-reinforced ceramic composites are can be candidate materials for structural applications requiring high
degrees of wear and corrosion resistance, and damage tolerance at high temperatures.
5.2 Shear tests provide information on the strength and deformation of materials under shear stresses.
Whitney, J., M., “Stress Analysis of the Double Notch Shear Specimen,” Proceedings of the American Society for Composites, 4th Technical Conference, Blacksburg
Virginia, Oct. 3–5, 1989, Technomic Publishing Co, pp.Co., p. 325.
Iosipescu, N., “New Accurate Procedure for Shear Testing of Metals,” Journal of Materials, Vol 2, No. 3, Sept. 1967, pp. 537–566.
C1292 − 22
FIG. 1 Schematic of Test Fixture for the Double-Notched
Compression Test Specimen
NOTE 1—All tolerances are in millimeters.
FIG. 2 Schematic of Double-Notched Compression Test
Specimen
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NOTE 1—The forces 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
FIG. 4 Schematic of Test Fixture for the Iosipescu Test
5.3 This test method may be used for material development, material comparison, quality assurance, characterization, and design
data generation.
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NOTE 1—All tolerances are in millimeters.
FIG. 5 Schematic of the Iosipescu Specimen
5.4 For quality control purposes, results derived from standardized 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.)etc.), including moisture content (for example, relative
humidity)humidity), may have an influence on the measured shear strength. In particular, the behavior of materials susceptible to
slow crack growth fracture will be strongly influenced by test environment and testing rate. Testing to evaluate the maximum
strength potential of a material shall be conducted in inert environments or at sufficiently rapid testing rates, or both, so as to
minimize slow crack growth effects. Conversely, testing can be conducted in environments and testing modes and rates
representative of service conditions to evaluate material performance under those conditions. When testing is conducted in
uncontrolled 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 recommendation
must be reported.
6.2 Preparation of test specimens, although normally not considered a major concern with CFCCs, can introduce fabrication flaws
which may have pronounced effects on the mechanical properties and behavior (for example, shape and level of the resulting
force-displacement curve and shear strength). Machining damage introduced during test 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 do not exist. Final machining steps
may,may or may not negate machining damage introduced during the initial machining. Thus, test specimen fabrication history
may play an important role in the measured strength distributions and shall be reported.
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6.3 Bending in uniaxially loaded shear tests can cause or promote nonuniform stress distributions that may alter the desired
uniform state of stress during the test.
6.4 Fractures that initiate outside the uniformly stressed gauge section of a test specimen may be due to factors such as localized
stress concentrations, extraneous stresses introduced by improper loading configurations, or strength-limiting features in the
microstructure of the specimen. Such non-gauge section fractures will normally constitute invalid tests.
6.5 For the conduction of the Iosipescu test, thin test specimens (width to thickness ratio of more than ten) may suffer from
splitting and instabilities rendering in turn invalid test results.
6.6 For the evaluation of the interlaminar shear strength by the compression of a double-notched test specimen, the distance
between the notches in the specimen has an effect on the maximum force and therefore on the shear strength. It has been found
that the stress distribution in the test specimen is independent of the distance between the notches when the notches are far apart.
However, when the distance between the notches is such that the stress fields around the notches interact, the measured interlaminar
shear strength increases. Because of the complexity of the stress field around each notch and its dependence on the properties and
homogeneity of the material, it is recommended to conduct a series of tests on test specimens with different spacing between the
notches to determine their effect on the measured interlaminar shear strength.
6.7 For the evaluation of the interlaminar shear strength by the compression of a double-notched test specimen, excessive
clamping force with the jaws will reduce the stress concentration around the notches and therefore artificially increase the
measured interlaminar shear strength. Because the purpose of the jaws is to maintain the specimen in place and to prevent buckling,
avoid overtightening the jaws.
6.8 Most test fixtures incorporate an alignment mechanism in the form of a guide rod and a linear roller bearing. Excessive free
play or excessive friction in this mechanism may introduce spurious moments that will alter the ideal loading conditions.
7. Apparatus
7.1 Testing Machines—The testing machine shall be in conformance with Practices E4. The forces used in determining shear
strength shall be accurate within 61 % at any force within the selected force range of the testing machine as defined in Practices
E4.
7.2 Data Acquisition—At the minimum, autographic records of applied force and cross-head displacement versus time shall be
obtained. Either analog chart recorders or Either digital data acquisition systems or analog chart recorders may be used for this
purposeas recording devices, although a digital record is recommended for ease of later data analysis. Ideally, an analog chart
recorder or plotter shall be used in conjunction with the digital data acquisition system to provide an immediate record of the test
as a supplement to the digital record. Recording devices must be accurate to 61 % of full scale and shall have a minimum data
acquisition rate of 10 Hz, with a response of 50 Hz deemed more than sufficient.
7.3 Dimension-Measuring Devices—Micrometers and other devices used for measuring linear dimensions must be accurate and
precise to at least 0.01 mm.
7.4 Test Fixtures:
7.4.1 Double-notchedDouble-Notched Compression Test Specimen—The test fixture consists of a stationary element mounted on
a base plate, an element that attaches to the crosshead of the testing machine, and two jaws to fix the test specimen in position.
A schematic description of the test fixture is shown in Fig. 1. A supporting jig conforming to the geometry of that shown in Fig.
1Figure 1 of Test Method D3846 or Fig. 4Figure 4 of Test Method D695 may also be used.
Lara-Curzio, E., “Properties of Continuous Fiber-Reinforced Ceramic Matrix Composites for Gas Turbine Applications,” Chapter 22,22 in Ceramic Gas Turbine Design
and Test Experience: Progress in Ceramic Gas Turbine Development, Vol.Vol 2, Ed. M. van Roode, M. K. Ferber, and D. W. Richerson. ASME Richerson, Eds., ASME, 2003,
pp. 441–491.
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TABLE 1 Recommended Dimensions for Double-Notched
Compression Specimen
Dimension Description Value, mm
L Specimen length 30.00
h Distance between notches 6.00
h Distance between notches 6.00
W Specimen width 15.00
d Notch width 0.50
d Notch width 0.50
t Specimen thickness . . .
7.4.2 Iosipescu Test Specimen—The test fixture shall be a four-point asymmetric flexure fixture shown schematically in Fig. 4.
This test fixture consists of a stationary element mounted on a base plate,plate and a movable element capable of vertical translation
guided by a stiff post. The movable element attaches to the cross-headcrosshead of the testing machine. Each element clamps half
of the test specimen into position with a wedge action grip able to compensate for minor width variations of the test specimen.
A span of 13 mm is left unsupported between test fixture halves. An alignment tool is recommended to ensure that the test specimen
notch is aligned with the line-of-action of the loading fixture.
8. Hazards
8.1 During the conduct of this test method, the possibility of flying fragments of broken test material may be high. The brittle
nature of advanced ceramics and the release of strain energy contribute to the potential release of uncontrolled fragments upon
fracture. Means for containment and retention of these fragments for later fractographic reconstruction and analysis is highly
recommended.
8.2 Exposed fibers at the edges of CFCC test specimens present a hazard due to the sharpness and brittleness of the ceramic fiber.
All persons required to handle these materials shall be well informed of these conditions and the proper handling techniques.
9. Test Specimens
9.1 Test Specimen Geometry:
9.1.1 Double-Notched Compression Test Specimen—The test specimens shall conform to the shape and tolerances shown in Fig.
2. The specimen consists of a rectangular plate with notches machined on both sides. The depth of the notches shall be at least
equal to one half of the test specimen thickness, and the distance between the notches shall be determined considering the
requirements to produce shear failure in the gauge section. Furthermore, because the measured interlaminar shear strength may be
dependent on the notch separation, it is recommended to conduct tests with different values of notch separation to determine this
dependence. The edges of the test specimens shall be smooth, but not rounded or beveled. Table 1 contains recommended values
for the dimensions associated with the test specimen shown in Fig. 2.
9.1.2 The Iosipescu Test Specimen—The required test specimen shape and tolerances are shown in Fig. 5, while Table 2 contains
recommended values for the test specimen dimensions. If required, the specimen dimensions, particularly the notch angle, notch
depth, and notch radius, may be adjusted to meet special material requirements, but any deviation from the recommended values
contained in Table 2 shall be reported with the test results, although the standard tolerances shown in Fig. 5 still apply. The shear
strength in any one of the principal shear planes of laminated CFCCs,CFCCs may be obtained by orienting the testing plane of
the test specimen with the desired composite material plane as indicated in Fig. 6 for example. End-tabs, adhesively bonded to both
faces of the test specimen away from the test section, are recommended to avoid local crushing failure and test specimen twisting
in the fixture.
9.1.2.1 Due to limitations in material processing, in some instances it may be difficult to produce thick sections to conform with
the dimensions and geometry shown in Table 2 and contained in Fig. 5 respectively,respectively; the test specimen geometry may
be modified in order to obtain appropriate results. This may be true if the interlaminar shear strength is sought by using the
Iosipescu test for example. In this case, adhesively bonded end-tabs may be used, and the depth and angle of the notches must be
selected to promote shear failure between the V-notches. Fig. 7 shows an example of this situation.
Available from several commercial test fixture suppliers or testing equipment companies.
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TABLE 2 Recommended Dimensions for Iosipescu Test
Specimen
Dimension Description Value
L Test Specimen length 76.00 mm
h Distance between notches 11.00 mm
W Test Specimen width 19.00 mm
R Notch radius 1.30 mm
R Notch radius 1.30 mm
θ Notch angle 90.0°
θ Notch angle 90.0°
t Test Specimen thickness . . .
t Test Specimen thickness . . .
FIG. 6 Orientation of Material Planes to Obtain the Strength of Any One of the Three Shear Planes of Laminated
...