ASTM C1341-13(2023)
(Test Method)Standard Test Method for Flexural Properties of Continuous Fiber-Reinforced Advanced Ceramic Composites
Standard Test Method for Flexural Properties of Continuous Fiber-Reinforced Advanced Ceramic Composites
SIGNIFICANCE AND USE
5.1 This test method is used for material development, quality control, and material flexural specifications. Although flexural test methods are commonly used to determine design strengths of monolithic advanced ceramics, the use of flexure test data for determining tensile or compressive properties of CFCC materials is strongly discouraged. The nonuniform stress distributions in the flexure test specimen, the dissimilar mechanical behavior in tension and compression for CFCCs, low shear strengths of CFCCs, and anisotropy in fiber architecture all lead to ambiguity in using flexure results for CFCC material design data (1-4).3 Rather, uniaxial-forced tensile and compressive tests are recommended for developing CFCC material design data based on a uniformly stressed test condition.
5.2 In this test method, the flexure stress is computed from elastic beam theory with the simplifying assumptions that the material is homogeneous and linearly elastic. This is valid for composites where the principal fiber direction is coincident/transverse with the axis of the beam. These assumptions are necessary to calculate a flexural strength value, but limit the application to comparative type testing such as used for material development, quality control, and flexure specifications. Such comparative testing requires consistent and standardized test conditions, that is, test specimen geometry/thickness, strain rates, and atmospheric/test conditions.
5.3 Unlike monolithic advanced ceramics which fracture catastrophically from a single dominant flaw, CFCCs generally experience “graceful” fracture from a cumulative damage process. Therefore, the volume of material subjected to a uniform flexural stress may not be as significant a factor in determining the flexural strength of CFCCs. However, the need to test a statistically significant number of flexure test specimens is not eliminated. Because of the probabilistic nature of the strength of the brittle matrices and of the ceramic...
SCOPE
1.1 This test method covers the determination of flexural properties of continuous fiber-reinforced ceramic composites in the form of rectangular bars formed directly or cut from sheets, plates, or molded shapes. Three test geometries are described as follows:
1.1.1 Test Geometry I—A three-point loading system utilizing center point force application on a simply supported beam.
1.1.2 Test Geometry IIA—A four-point loading system utilizing two force application points equally spaced from their adjacent support points, with a distance between force application points of one-half of the support span.
1.1.3 Test Geometry IIB—A four-point loading system utilizing two force application points equally spaced from their adjacent support points, with a distance between force application points of one-third of the support span.
1.2 This test method applies primarily to all advanced ceramic matrix composites with continuous fiber reinforcement: unidirectional (1D), bidirectional (2D), tridirectional (3D), and other continuous fiber architectures. In addition, this test method may also be used with glass (amorphous) matrix composites with continuous fiber reinforcement. However, flexural strength cannot be determined for those materials that do not break or fail by tension or compression in the outer fibers. This test method does not directly address discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics. Those types of ceramic matrix composites are better tested in flexure using Test Methods C1161 and C1211.
1.3 Tests can be performed at ambient temperatures or at elevated temperatures. At elevated temperatures, a suitable furnace is necessary for heating and holding the test specimens at the desired testing temperatures.
1.4 This test method includes the following:
Section
Scope
1
Referenced Documents
2
Terminology
3
Summary of Test Method
...
General Information
Relations
Standards Content (Sample)
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.
Designation: C1341 − 13 (Reapproved 2023)
Standard Test Method for
Flexural Properties of Continuous Fiber-Reinforced
Advanced Ceramic Composites
This standard is issued under the fixed designation C1341; 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
Referenced Documents 2
Terminology 3
1.1 This test method covers the determination of flexural
Summary of Test Method 4
properties of continuous fiber-reinforced ceramic composites Significance and Use 5
Interferences 6
in the form of rectangular bars formed directly or cut from
Apparatus 7
sheets, plates, or molded shapes. Three test geometries are
Precautionary Statement 8
described as follows: Test Specimens 9
Procedures 10
1.1.1 Test Geometry I—A three-point loading system utiliz-
Calculation of Results 11
ing center point force application on a simply supported beam.
Report 12
Precision and Bias 13
1.1.2 Test Geometry IIA—A four-point loading system uti-
Keywords 14
lizing two force application points equally spaced from their
References
adjacent support points, with a distance between force appli-
CFCC Surface Condition and Finishing Annex A1
Conditions and Issues in Hot Loading of Test Annex A2
cation points of one-half of the support span.
Specimens into Furnaces
1.1.3 Test Geometry IIB—A four-point loading system uti-
Toe Compensation on Stress-Strain Curves Annex A3
lizing two force application points equally spaced from their
Corrections for Thermal Expansion in Flexural Annex A4
Equations
adjacent support points, with a distance between force appli-
Example of Test Report Appendix X1
cation points of one-third of the support span.
1.5 The values stated in SI units are to be regarded as the
1.2 This test method applies primarily to all advanced
standard in accordance with IEEE/ASTM SI 10.
ceramic matrix composites with continuous fiber reinforce-
1.6 This standard does not purport to address all of the
ment: unidirectional (1D), bidirectional (2D), tridirectional
safety concerns, if any, associated with its use. It is the
(3D), and other continuous fiber architectures. In addition, this
responsibility of the user of this standard to establish appro-
test method may also be used with glass (amorphous) matrix
priate safety, health, and environmental practices and deter-
composites with continuous fiber reinforcement. However,
mine the applicability of regulatory limitations prior to use.
flexural strength cannot be determined for those materials that
1.7 This international standard was developed in accor-
do not break or fail by tension or compression in the outer
dance with internationally recognized principles on standard-
fibers. This test method does not directly address discontinuous
ization established in the Decision on Principles for the
fiber-reinforced, whisker-reinforced, or particulate-reinforced
Development of International Standards, Guides and Recom-
ceramics. Those types of ceramic matrix composites are better
mendations issued by the World Trade Organization Technical
tested in flexure using Test Methods C1161 and C1211.
Barriers to Trade (TBT) Committee.
1.3 Tests can be performed at ambient temperatures or at
elevated temperatures. At elevated temperatures, a suitable
2. Referenced Documents
furnace is necessary for heating and holding the test specimens
2.1 ASTM Standards:
at the desired testing temperatures.
C1145 Terminology of Advanced Ceramics
1.4 This test method includes the following:
C1161 Test Method for Flexural Strength of Advanced
Section
Ceramics at Ambient Temperature
Scope 1
C1211 Test Method for Flexural Strength of Advanced
Ceramics at Elevated Temperatures
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2023. Published June 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2018 as C1341 – 13 (2018). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/C1341-13R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1341 − 13 (2023)
C1239 Practice for Reporting Uniaxial Strength Data and nature. These components are combined on a macroscale to
Estimating Weibull Distribution Parameters for Advanced form a useful engineering material possessing certain proper-
Ceramics ties or behavior not possessed by the individual constituents.
C1292 Test Method for Shear Strength of Continuous Fiber-
3.1.5 continuous fiber-reinforced ceramic composite
Reinforced Advanced Ceramics at Ambient Temperatures
(CFCC), n—ceramic matrix composite in which the reinforc-
D790 Test Methods for Flexural Properties of Unreinforced
ing phase consists of a continuous fiber, continuous yarn, or a
and Reinforced Plastics and Electrical Insulating Materi-
woven fabric.
als
−2
3.1.6 flexural strength [FL ], n—measure of the ultimate
D2344/D2344M Test Method for Short-Beam Strength of
strength of a specified beam in bending. C1161
Polymer Matrix Composite Materials and Their Laminates
D3878 Terminology for Composite Materials 3.1.7 four-point- ⁄3-point flexure, n—a configuration of flex-
ural strength testing where a test specimen is symmetrically
D6856/D6856M Guide for Testing Fabric-Reinforced “Tex-
tile” Composite Materials loaded at two locations that are situated one-third of the overall
span away from the outer two support bearings.
E4 Practices for Force Calibration and Verification of Test-
ing Machines
3.1.8 four-point- ⁄4-point flexure, n—a configuration of flex-
E6 Terminology Relating to Methods of Mechanical Testing
ural strength testing where a test specimen is symmetrically
E122 Practice for Calculating Sample Size to Estimate, With
loaded at two locations that are situated one-quarter of the
Specified Precision, the Average for a Characteristic of a
overall span away from the outer two support bearings. C1161
Lot or Process
−2
3.1.9 fracture strength [FL ], n—the calculated flexural
E177 Practice for Use of the Terms Precision and Bias in
stress at the breaking force.
ASTM Test Methods
−2
3.1.10 modulus of elasticity [FL ], n—the ratio of stress to
E220 Test Method for Calibration of Thermocouples By
corresponding strain below the proportional limit. E6
Comparison Techniques
−2
E337 Test Method for Measuring Humidity with a Psy-
3.1.11 proportional limit stress [FL ], n—greatest stress
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
that a material is capable of sustaining without any deviation
peratures)
from proportionality of stress to strain (Hooke’s law).
E691 Practice for Conducting an Interlaboratory Study to
3.1.11.1 Discussion—Many experiments have shown that
Determine the Precision of a Test Method
values observed for the proportional limit vary greatly with the
IEEE/ASTM SI 10 American National Standard for Use of
sensitivity and accuracy of the testing equipment, eccentricity
the International System of Units (SI): The Modern Metric
of force application, the scale to which the stress-strain
System
diagram is plotted, and other factors. When determination of
proportional limit is required, the procedure and sensitivity of
3. Terminology
the test equipment shall be specified. E6
3.1 Definitions:
3.1.12 slow crack growth, n—subcritical crack growth (ex-
3.1.1 The definitions of terms relating to flexure testing
tension) that may result from, but is not restricted to, such
appearing in Terminology E6 apply to the terms used in this
mechanisms as environmentally assisted stress corrosion or
test method. The definitions of terms relating to advanced
diffusive crack growth.
ceramics appearing in Terminology C1145 apply to the terms
3.1.13 span-to-depth ratio [nd], n—for a particular test
used in this test method. The definitions of terms relating to
specimen geometry and flexure test configuration, the ratio
fiber-reinforced composites appearing in Terminology D3878
(L/d) of the outer support span length (L) of the flexure test
apply to the terms used in this test method. Pertinent definitions
specimen to the thickness/depth (d) of test specimen (as used
as listed in Test Method C1161, Test Methods D790, Termi-
and described in Test Methods D790).
nology C1145, Terminology D3878, and Terminology E6 are
shown in the following, with the appropriate source given in 3.1.14 three-point flexure, n—a configuration of flexural
strength testing where a test specimen is loaded at a location
brackets. Additional terms used in conjunction with this test
method are also defined in the following. midway between two support bearings. C1161
3.1.2 advanced ceramic, n—highly engineered, high-
performance, predominately nonmetallic, inorganic, ceramic 4. Summary of Test Method
material having specific functional attributes. C1145
4.1 A bar of rectangular cross section is tested in flexure as
3.1.3 breaking force [F], n—the force at which fracture
a beam as in one of the following three geometries:
occurs. (In this test method, fracture consists of breakage of the
4.1.1 Test Geometry I—The bar rests on two supports and
test bar into two or more pieces or a loss of at least 20 % of the
force is applied by means of a loading roller midway between
maximum force carrying capacity.) E6
the supports (see Fig. 1).
3.1.4 ceramic matrix composite, n—material consisting of 4.1.2 Test Geometry IIA—The bar rests on two supports and
two or more materials (insoluble in one another) in which the force is applied at two points (by means of two inner rollers),
major, continuous component (matrix component) is a ceramic, each an equal distance from the adjacent outer support point.
while the secondary component(s) (reinforcing component) The inner support points are situated one-quarter of the overall
may be ceramic, glass-ceramic, glass, metal, or organic in span away from the outer two support bearings. The distance
C1341 − 13 (2023)
FIG. 1 Flexure Test Geometries and Force Diagram
between the inner rollers (that is, the load span) is one-half of material design data (1-4). Rather, uniaxial-forced tensile and
the support span (see Fig. 1). compressive tests are recommended for developing CFCC
4.1.3 Test Geometry IIB—The bar rests on two supports and material design data based on a uniformly stressed test condi-
force is applied at two points (by means of two loading rollers), tion.
situated one-third of the overall span away from the outer two
5.2 In this test method, the flexure stress is computed from
support bearings. The distance between the inner rollers (that
elastic beam theory with the simplifying assumptions that the
is, the inner support span) is one-third of the outer support span
material is homogeneous and linearly elastic. This is valid for
(see Fig. 1).
composites where the principal fiber direction is coincident/
4.2 The test specimen is deflected until rupture occurs in the transverse with the axis of the beam. These assumptions are
outer fibers or until there is a 20 % decrease from the peak necessary to calculate a flexural strength value, but limit the
force. application to comparative type testing such as used for
material development, quality control, and flexure specifica-
4.3 The flexural properties of the test specimen (flexural
tions. Such comparative testing requires consistent and stan-
strength and strain, fracture strength and strain, modulus of
dardized test conditions, that is, test specimen geometry/
elasticity, and stress-strain curves) are calculated from the
thickness, strain rates, and atmospheric/test conditions.
force and deflection using elastic beam equations.
5.3 Unlike monolithic advanced ceramics which fracture
5. Significance and Use
catastrophically from a single dominant flaw, CFCCs generally
experience “graceful” fracture from a cumulative damage
5.1 This test method is used for material development,
process. Therefore, the volume of material subjected to a
quality control, and material flexural specifications. Although
uniform flexural stress may not be as significant a factor in
flexural test methods are commonly used to determine design
determining the flexural strength of CFCCs. However, the need
strengths of monolithic advanced ceramics, the use of flexure
to test a statistically significant number of flexure test speci-
test data for determining tensile or compressive properties of
mens is not eliminated. Because of the probabilistic nature of
CFCC materials is strongly discouraged. The nonuniform
the strength of the brittle matrices and of the ceramic fiber in
stress distributions in the flexure test specimen, the dissimilar
mechanical behavior in tension and compression for CFCCs,
low shear strengths of CFCCs, and anisotropy in fiber archi-
The boldface numbers in parentheses refer to a list of references at the end of
tecture all lead to ambiguity in using flexure results for CFCC this standard.
C1341 − 13 (2023)
CFCCs, a sufficient number of test specimens at each testing geometry of the test specimen must be chosen so that shear
condition is required for statistical analysis, with guidelines for stresses are kept low relative to the tension and compression
sufficient numbers provided in 9.7. Studies to determine the stresses. This is done by maintaining a high ratio between the
exact influence of test specimen volume on strength distribu- support span (L) and the thickness/depth (d) of the test
tions for CFCCs are not currently available. specimen. This L/d ratio is generally kept at values of ≥16 for
three-point testing and ≥30 for four-point testing. If the
5.4 The four-point loading geometries (Geometries IIA and
span-to-depth ratio is too low, the test specimen may fail in
IIB) are preferred over the three-point loading geometry
shear, invalidating the test. If the desired mode of failure is
(Geometry I). In the four-point loading geometry, a larger
shear, then an appropriate shear test method should be used,
portion of the test specimen is subjected to the maximum
such as Test Method C1292 or D2344/D2344M.
tensile and compressive stresses, as compared to the three-
...
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