ASTM C1360-10(2015)
(Practice)Standard Practice for Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures
Standard Practice for Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures
SIGNIFICANCE AND USE
4.1 This practice may be used for material development, material comparison, quality assurance, characterization, reliability assessment, and design data generation.
4.2 Continuous fiber-reinforced ceramic matrix composites are generally characterized by crystalline matrices and ceramic fiber reinforcements. These materials are candidate materials for structural applications requiring high degrees of wear and corrosion resistance, and high-temperature inherent damage tolerance (that is, toughness). In addition, continuous fiber-reinforced glass matrix composites are candidate materials for similar but possibly less-demanding applications. Although flexural test methods are commonly used to evaluate the mechanical behavior of monolithic advanced ceramics, the non-uniform stress distribution in a flexural test specimen in addition to dissimilar mechanical behavior in tension and compression for CFCCs leads to ambiguity of interpretation of test results obtained in flexure for CFCCs. Uniaxially-loaded tensile tests provide information on mechanical behavior for a uniformly stressed material.
4.3 The cyclic fatigue behavior of CFCCs can have appreciable non-linear effects (for example, sliding of fibers within the matrix) which may be related to the heat transfer of the specimen to the surroundings. Changes in test temperature, frequency, and heat removal can affect test results. It may be desirable to measure the effects of these variables to more closely simulate end-use conditions for some specific application.
4.4 Cyclic fatigue by its nature is a probabilistic phenomenon as discussed in STP 91A (Ref (1)) and STP 588 (Ref (2)).4 In addition, the strengths of the brittle matrices and fibers of CFCCs are probabilistic in nature. Therefore, a sufficient number of test specimens at each testing condition is required for statistical analysis and design, with guidelines for sufficient numbers provided in STP 91A (Ref (1)), STP 588 (Ref (2)), and Practice E739. St...
SCOPE
1.1 This practice covers the determination of constant-amplitude, axial tension-tension cyclic fatigue behavior and performance of continuous fiber-reinforced advanced ceramic composites (CFCCs) at ambient temperatures. This practice builds on experience and existing standards in tensile testing CFCCs at ambient temperatures and addresses various suggested test specimen geometries, specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates and frequencies, allowable bending, and procedures for data collection and reporting. This practice does not apply to axial cyclic fatigue tests of components or parts (that is, machine elements with nonuniform or multiaxial stress states).
1.2 This practice applies primarily to advanced ceramic matrix composites with continuous fiber reinforcement: uni-directional (1-D), bi-directional (2-D), and tri-directional (3-D) or other multi-directional reinforcements. In addition, this practice may also be used with glass (amorphous) matrix composites with 1-D, 2-D, 3-D, and other multi-directional continuous fiber reinforcements. This practice does not directly address discontinuous fiber-reinforced, whisker-reinforced or particulate-reinforced ceramics, although the methods detailed here may be equally applicable to these composites.
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 and health practices and determine the applicability of regulatory limitations prior to use. Refer to Section 7 for specific precautions.
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Designation: C1360 − 10 (Reapproved 2015)
Standard Practice for
Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue
of Continuous Fiber-Reinforced Advanced Ceramics at
Ambient Temperatures
This standard is issued under the fixed designation C1360; 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* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice covers the determination of constant-
C1145 Terminology of Advanced Ceramics
amplitude, axial tension-tension cyclic fatigue behavior and
C1275 Test Method for Monotonic Tensile Behavior of
performance of continuous fiber-reinforced advanced ceramic
Continuous Fiber-Reinforced Advanced Ceramics with
composites (CFCCs) at ambient temperatures. This practice
Solid Rectangular Cross-Section Test Specimens at Am-
builds on experience and existing standards in tensile testing
bient Temperature
CFCCs at ambient temperatures and addresses various sug-
D3479/D3479M Test Method for Tension-Tension Fatigue
gested test specimen geometries, specimen fabrication
of Polymer Matrix Composite Materials
methods,testingmodes(force,displacement,orstraincontrol),
D3878 Terminology for Composite Materials
testing rates and frequencies, allowable bending, and proce-
E4 Practices for Force Verification of Testing Machines
dures for data collection and reporting. This practice does not
E6 Terminology Relating to Methods of Mechanical Testing
apply to axial cyclic fatigue tests of components or parts (that
E83 Practice for Verification and Classification of Exten-
is, machine elements with nonuniform or multiaxial stress
someter Systems
states).
E337 Test Method for Measuring Humidity with a Psy-
1.2 This practice applies primarily to advanced ceramic
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
matrix composites with continuous fiber reinforcement: uni-
peratures)
directional(1-D),bi-directional(2-D),andtri-directional(3-D)
E467 Practice for Verification of Constant Amplitude Dy-
or other multi-directional reinforcements. In addition, this
namic Forces in an Axial Fatigue Testing System
practice may also be used with glass (amorphous) matrix
E468 Practice for Presentation of Constant Amplitude Fa-
composites with 1-D, 2-D, 3-D, and other multi-directional
tigue Test Results for Metallic Materials
continuousfiberreinforcements.Thispracticedoesnotdirectly
E739 PracticeforStatisticalAnalysisofLinearorLinearized
address discontinuous fiber-reinforced, whisker-reinforced or
Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
particulate-reinforced ceramics, although the methods detailed
E1012 Practice for Verification of Testing Frame and Speci-
here may be equally applicable to these composites.
men Alignment Under Tensile and Compressive Axial
Force Application
1.3 The values stated in SI units are to be regarded as the
E1150 Definitions of Terms Relating to Fatigue (Withdrawn
standard and are in accordance with IEEE/ASTM SI 10 .
1996)
1.4 This standard does not purport to address all of the
E1823 TerminologyRelatingtoFatigueandFractureTesting
safety concerns, if any, associated with its use. It is the
IEEE/ASTM SI 10 Standard for Use of the International
responsibility of the user of this standard to establish appro-
System of Units (SI) (The Modern Metric System)
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Refer to Section 7 3. Terminology
for specific precautions.
3.1 Definitions:
1 2
This practice is under the jurisdiction of ASTM Committee C28 on Advanced For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Ceramics and is the direct responsibility of Subcommittee C28.07 on Ceramic contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Matrix Composites. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved July 1, 2015. Published September 2015. Originally the ASTM website.
approved in 1996. Last previous edition approved in 2010 as C1360 – 10. DOI: The last approved version of this historical standard is referenced on
10.1520/C1360-10R15. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1360 − 10 (2015)
3.1.1 Definitions of terms relating to advanced ceramics,
fiber-reinforced composites, tensile testing, and cyclic fatigue
as they appear in Terminology C1145, Terminology D3878,
Terminology E6, and Terminology E1823, respectively, apply
to the terms used in this practice. Selected terms with defini-
tions non specific to this practice follow in 3.2 with the
appropriate source given in parenthesis. Terms specific to this
practice are defined in 3.3.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 advanced ceramic, n—A highly engineered, high per-
formance predominately non-metallic, inorganic, ceramic ma-
terial having specific functional attributes. (See Terminology
C1145.)
–1
3.2.2 axial strain [LL ], n—theaveragelongitudinalstrains
measured at the surface on opposite sides of the longitudinal
FIG. 1 Cyclic Fatigue Nomenclature and Wave Forms
axis of symmetry of the test specimen by two strain-sensing
devices located at the mid length of the reduced section. (See
Practice E1012.)
–1
3.2.9.1 Discussion—Certain materials and environments
3.2.3 bending strain [LL ], n—the difference between the
preclude the attainment of a cyclic fatigue limit. Values
strainatthesurfaceandtheaxialstrain.Ingeneral,thebending
tabulated as “fatigue limits” in the literature are frequently (but
strain varies from point to point around and along the reduced
not always) values of S at 50 % survival at N cycles of stress
section of the test specimen. (See Practice E1012.)
f f
in which the mean stress, S , equals zero.
m
3.2.4 ceramic matrix composite, n—a material consisting of
two or more materials (insoluble in one another), in which the 3.2.10 cyclic fatigue strength S , [FL ], n—the limiting
N
valueofthemediancyclicfatiguestrengthataparticularcyclic
major,continuouscomponent(matrixcomponent)isaceramic,
while the secondary component(s) (reinforcing component) fatigue life, N (See Terminology E1823).
f
may be ceramic, glass-ceramic, glass, metal or organic in
3.2.11 gage length, [L], n—the original length of that
nature. These components are combined on a macroscale to
portion of the test specimen over which strain or change of
form a useful engineering material possessing certain proper-
length is determined. (See Terminology E6.)
ties or behavior not possessed by the individual constituents.
3.2.12 force ratio, n—incyclicfatigueloading,thealgebraic
(See Test Method C1275.)
ratio of the two loading parameters of a cycle; the most widely
3.2.5 continuous fiber-reinforced ceramic matrix composite
used ratios (See Terminology E1150, E1823):
(CFCC), n—a ceramic matrix composite in which the reinforc-
minimum force valley force
ing phase consists of a continuous fiber, continuous yarn, or a
R 5 or R 5
maximum force peak force
woven fabric. (See Terminology C1145.)
and
3.2.6 constant amplitude loading, n—in cyclic fatigue
force amplitude maximum force 2 minimum force
~ !
loading, a loading in which all peak loads are equal and all of
A 5 or A 5
mean force ~maximum force1minimum force!
the valley loads are equal. (See Terminology E1823.)
–2
3.2.7 cyclic fatigue, n—the process of progressive localized 3.2.13 matrix-cracking stress [FL ], n—The applied ten-
sile stress at which the matrix cracks into a series of roughly
permanent structural change occurring in a material subjected
to conditions that produce fluctuating stresses and strains at parallel blocks normal to the tensile stress. (See Test Method
C1275.)
some point or points and that may culminate in cracks or
3.2.13.1 Discussion—In some cases, the matrix-cracking
completefractureafterasufficientnumberoffluctuations. (See
stress may be indicated on the stress-strain curve by deviation
Terminology E1823.) See Fig. 1 for nomenclature relevant to
from linearity (proportional limit) or incremental drops in the
cyclic fatigue testing.
stress with increasing strain. In other cases, especially with
3.2.7.1 Discussion—In glass technology static tests of con-
materialsthatdonotpossessalinearportionofthestress-strain
siderable duration are called “static fatigue” tests, a type of test
curve, the matrix cracking stress may be indicated as the first
generally designated as stress-rupture.
stress at which a permanent offset strain is detected in the
3.2.7.2 Discussion—Fluctuations may occur both in force
unloading stress-strain curve (elastic limit).
andwithtime(frequency)asinthecaseof“randomvibration.”
–2
3.2.14 modulus of elasticity [FL ], n—The ratio of stress to
3.2.8 cyclic fatigue life, N—thenumberofloadingcyclesof
f
a specified character that a given test specimen sustains before corresponding strain below the proportional limit. (See Termi-
nology E6.)
failure of a specified nature occurs. (See Terminology E1823.)
–2
–2
3.2.9 cyclic fatigue limit, S [FL ], n—the limiting value of 3.2.15 proportional limit stress [FL ], n—the greatest
f
the median cyclic fatigue strength as the cyclic fatigue life, N, stress that a material is capable of sustaining without any
f
6 7
becomes very large, (for example, Nf 10 –10 ). (See deviationfromproportionalityofstresstostrain(Hooke’slaw).
Terminology E1823.) (See Terminology E6.)
C1360 − 10 (2015)
3.2.15.1 Discussion—Many experiments have shown that 4. Significance and Use
values observed for the proportional limit vary greatly with the
4.1 This practice may be used for material development,
sensitivity and accuracy of the testing equipment, eccentricity
material comparison, quality assurance, characterization, reli-
of loading, the scale to which the stress-strain diagram is
ability assessment, and design data generation.
plotted, and other factors. When determination of proportional
4.2 Continuous fiber-reinforced ceramic matrix composites
limit is required, specify the procedure and sensitivity of the
are generally characterized by crystalline matrices and ceramic
test equipment.
fiber reinforcements. These materials are candidate materials
3.2.16 percent bending, n—the bending strain times 100
for structural applications requiring high degrees of wear and
divided by the axial strain. (See Practice E1012.)
corrosion resistance, and high-temperature inherent damage
3.2.17 S-N diagram, n—aplotofstressversusthenumberof
tolerance (that is, toughness). In addition, continuous fiber-
cycles to failure. The stress can be maximum stress, S , reinforced glass matrix composites are candidate materials for
max
minimum stress, S , stress range, ∆S or S , or stress
similar but possibly less-demanding applications. Although
min r
amplitude, S . The diagram indicates the S-N relationship for a flexural test methods are commonly used to evaluate the
a
specified value of S , Α , R and a specified probability of mechanical behavior of monolithic advanced ceramics, the
m
survival. For N, a log scale is almost always used, although a non-uniform stress distribution in a flexural test specimen in
linear scale may also be used. For S, a linear scale is usually addition to dissimilar mechanical behavior in tension and
used, although a log scale may also be used. (See Terminology compression for CFCCs leads to ambiguity of interpretation of
E1150 and Practice E468.) test results obtained in flexure for CFCCs. Uniaxially-loaded
tensile tests provide information on mechanical behavior for a
3.2.18 slow crack growth, n—sub-critical crack growth
uniformly stressed material.
(extension) that may result from, but is not restricted to, such
mechanisms as environmentally-assisted stress corrosion or
4.3 The cyclic fatigue behavior of CFCCs can have appre-
diffusive crack growth (See Test Method C1275). ciable non-linear effects (for example, sliding of fibers within
–2
the matrix) which may be related to the heat transfer of the
3.2.19 tensile strength [FL ], n—the maximum tensile
specimen to the surroundings. Changes in test temperature,
stress which a material is capable of sustaining. Tensile
frequency, and heat removal can affect test results. It may be
strengthiscalculatedfromthemaximumforceduringatension
desirable to measure the effects of these variables to more
test carried to rupture and the original cross-sectional area of
closely simulate end-use conditions for some specific applica-
the test specimen. (See Terminology E6.)
tion.
3.3 Definitions of Terms Specific to This Standard:
–2 4.4 Cyclic fatigue by its nature is a probabilistic phenom-
3.3.1 fracture strength [FL ], n—the tensile stress that the
enonasdiscussedinSTP91A(Ref (1))andSTP588(Ref (2)).
material sustains at the instant of fracture. Fracture strength is
In addition, the strengths of the brittle matrices and fibers of
calculated from the force at fracture during a tension test
CFCCs are probabilistic in nature. Therefore, a sufficient
carried to rupture and the original cross-sectional area of the
number of test specimens at each testing condition is required
test specimen.
for statistical analysis and design, with guidelines for sufficient
3.3.1.1 Discussion—In some cases, the fracture strength
numbers provided in STP 91A (Ref (1)), STP 588 (Ref (2)),
may be identical to the tensile strength if the force at fracture
and Practice E739. Studies to determine the influence of test
is the maximum for the test.
specimen volume or surface area on cyclic fatigue strength
–2
3.3.2 maximum stress, S [FL ], n—themaximumapplied
min distributions for CFCCs have not been completed. The many
stress during cyclic fatigue.
different tensile test specimen geometries available for cyclic
–2
fatigue testing may result in variations in the measured cyclic
3.3.3 mean stress,S [FL ], n—the difference between the
a
fatigue behavior of a particular material due to differences in
mean stress and the maximum or minimum stress such that
the volume of material in the gage section of the test speci-
S 1S
max min
mens.
S 5 (1)
m
4.5 Tensile cyclic fatigue tests provide information on the
–2]
3.3.4 minimum stress, S [FL ,n—the minimum applied
min
material response under fluctuating uniaxial tensile stresses.
stress during cyclic fatigue.
Uniform stress states are required to effectively evaluate any
–2]
3.3.5 stress amplitude, S [FL ,n—the difference between
a nonlinear stress-st
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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
of the standard as published by ASTM is to be considered the official document.
Designation: C1360 − 10 C1360 − 10 (Reapproved 2015)
Standard Practice for
Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue
of Continuous Fiber-Reinforced Advanced Ceramics at
Ambient Temperatures
This standard is issued under the fixed designation C1360; 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 practice covers the determination of constant-amplitude, axial tension-tension cyclic fatigue behavior and performance
of continuous fiber-reinforced advanced ceramic composites (CFCCs) at ambient temperatures. This practice builds on experience
and existing standards in tensile testing CFCCs at ambient temperatures and addresses various suggested test specimen geometries,
specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates and frequencies, allowable
bending, and procedures for data collection and reporting. This practice does not apply to axial cyclic fatigue tests of components
or parts (that is, machine elements with nonuniform or multiaxial stress states).
1.2 This practice applies primarily to advanced ceramic matrix composites with continuous fiber reinforcement: uni-directional
(1-D), bi-directional (2-D), and tri-directional (3-D) or other multi-directional reinforcements. In addition, this practice may also
be used with glass (amorphous) matrix composites with 1-D, 2-D, 3-D, and other multi-directional continuous fiber reinforcements.
This practice does not directly address discontinuous fiber-reinforced, whisker-reinforced or particulate-reinforced ceramics,
although the methods detailed here may be equally applicable to these composites.
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 and health practices and determine the applicability of regulatory
limitations prior to use. Refer to Section 7 for specific precautions.
2. Referenced Documents
2.1 ASTM Standards:
C1145 Terminology of Advanced Ceramics
C1275 Test Method for Monotonic Tensile Behavior of Continuous Fiber-Reinforced Advanced Ceramics with Solid
Rectangular Cross-Section Test Specimens at Ambient Temperature
D3479/D3479M Test Method for Tension-Tension Fatigue of Polymer Matrix Composite Materials
D3878 Terminology for Composite Materials
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E83 Practice for Verification and Classification of Extensometer Systems
E337 Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)
E467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
E468 Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic Materials
E739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
E1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial Force
Application
E1150 Definitions of Terms Relating to Fatigue (Withdrawn 1996)
This practice 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 July 15, 2010July 1, 2015. Published August 2010September 2015. Originally approved in 1996. Last previous edition approved in 20072010
as C1360 – 01C1360 – 10. (2007). DOI: 10.1520/C1360-10.10.1520/C1360-10R15.
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.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1360 − 10 (2015)
E1823 Terminology Relating to Fatigue and Fracture Testing
IEEE/ASTM SI 10 Standard for Use of the International System of Units (SI) (The Modern Metric System)
3. Terminology
3.1 Definitions:
3.1.1 Definitions of terms relating to advanced ceramics, fiber-reinforced composites, tensile testing, and cyclic fatigue as they
appear in Terminology C1145, Terminology D3878, Terminology E6, and Terminology E1823, respectively, apply to the terms
used in this practice. Selected terms with definitions non specific to this practice follow in 3.2 with the appropriate source given
in parenthesis. Terms specific to this practice are defined in 3.3.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 advanced ceramic, n—A highly engineered, high performance predominately non-metallic, inorganic, ceramic material
having specific functional attributes. (See Terminology C1145.)
–1
3.2.2 axial strain [LL ], n—the average longitudinal strains measured at the surface on opposite sides of the longitudinal axis
of symmetry of the test specimen by two strain-sensing devices located at the mid length of the reduced section. (See Practice
E1012.)
–1
3.2.3 bending strain [LL ], n—the difference between the strain at the surface and the axial strain. In general, the bending strain
varies from point to point around and along the reduced section of the test specimen. (See Practice E1012.)
3.2.4 ceramic matrix composite, n—a material consisting of two or more materials (insoluble in one another), in which the
major, continuous component (matrix component) is a ceramic, while the secondary component(s) (reinforcing component) may
be ceramic, glass-ceramic, glass, metal or organic in nature. These components are combined on a macroscale to form a useful
engineering material possessing certain properties or behavior not possessed by the individual constituents. (See Test Method
C1275.)
3.2.5 continuous fiber-reinforced ceramic matrix composite (CFCC), n—a ceramic matrix composite in which the reinforcing
phase consists of a continuous fiber, continuous yarn, or a woven fabric. (See Terminology C1145.)
3.2.6 constant amplitude loading, n—in cyclic fatigue loading, a loading in which all peak loads are equal and all of the valley
loads are equal. (See Terminology E1823.)
3.2.7 cyclic fatigue, n—the process of progressive localized permanent structural change occurring in a material subjected to
conditions that produce fluctuating stresses and strains at some point or points and that may culminate in cracks or complete
fracture after a sufficient number of fluctuations. (See Terminology E1823.) See Fig. 1 for nomenclature relevant to cyclic fatigue
testing.
3.2.7.1 Discussion—
In glass technology static tests of considerable duration are called “static fatigue” tests, a type of test generally designated as
stress-rupture.
3.2.7.2 Discussion—
Fluctuations may occur both in force and with time (frequency) as in the case of “random vibration.”
FIG. 1 Cyclic Fatigue Nomenclature and Wave Forms
C1360 − 10 (2015)
3.2.8 cyclic fatigue life, N —the number of loading cycles of a specified character that a given test specimen sustains before
f
failure of a specified nature occurs. (See Terminology E1823.)
–2
3.2.9 cyclic fatigue limit, S [FL ], n—the limiting value of the median cyclic fatigue strength as the cyclic fatigue life, N ,
f f
6 7
becomes very large, (for example, Nf 10 – 10 ). (See Terminology E1823.)
3.2.9.1 Discussion—
Certain materials and environments preclude the attainment of a cyclic fatigue limit. Values tabulated as “fatigue limits” in the
literature are frequently (but not always) values of S at 50 % survival at N cycles of stress in which the mean stress, S , equals
f f m
zero.
3.2.10 cyclic fatigue strength S , [FL ], n—the limiting value of the median cyclic fatigue strength at a particular cyclic fatigue
N
life, N (See Terminology E1823).
f
3.2.11 gage length, [L], n—the original length of that portion of the test specimen over which strain or change of length is
determined. (See Terminology E6.)
3.2.12 force ratio, n—in cyclic fatigue loading, the algebraic ratio of the two loading parameters of a cycle; the most widely
used ratios (See Terminology E1150, E1823):
minimum force valley force
R 5 or R 5
maximum force peak force
and
force amplitude maximum force 2 minimum force
~ !
A 5 or A 5
mean force maximum force1minimum force
~ !
– 2
3.2.13 matrix-cracking stress [FL ], n—The applied tensile stress at which the matrix cracks into a series of roughly parallel
blocks normal to the tensile stress. (See Test Method C1275.)
3.2.13.1 Discussion—
In some cases, the matrix-cracking stress may be indicated on the stress-strain curve by deviation from linearity (proportional limit)
or incremental drops in the stress with increasing strain. In other cases, especially with materials that do not possess a linear portion
of the stress-strain curve, the matrix cracking stress may be indicated as the first stress at which a permanent offset strain is detected
in the unloading stress-strain curve (elastic limit).
–2
3.2.14 modulus of elasticity [FL ], n—The ratio of stress to corresponding strain below the proportional limit. (See
Terminology E6.)
–2
3.2.15 proportional limit stress [FL ], n—the greatest stress that a material is capable of sustaining without any deviation from
proportionality of stress to strain (Hooke’s law). (See Terminology E6.)
3.2.15.1 Discussion—
Many experiments have shown that values observed for the proportional limit vary greatly with the sensitivity and accuracy of the
testing equipment, eccentricity of loading, the scale to which the stress-strain diagram is plotted, and other factors. When
determination of proportional limit is required, specify the procedure and sensitivity of the test equipment.
3.2.16 percent bending, n—the bending strain times 100 divided by the axial strain. (See Practice E1012.)
3.2.17 S-N diagram, n—a plot of stress versus the number of cycles to failure. The stress can be maximum stress, S ,
max
minimum stress, S , stress range, ΔS or S , or stress amplitude, S . The diagram indicates the S-N relationship for a specified
min r a
value of S , Α , R and a specified probability of survival. For N, a log scale is almost always used, although a linear scale may
m
also be used. For S, a linear scale is usually used, although a log scale may also be used. (See Terminology E1150 and Practice
E468.)
3.2.18 slow crack growth, n—sub-critical crack growth (extension) that may result from, but is not restricted to, such
mechanisms as environmentally-assisted stress corrosion or diffusive crack growth (See Test Method C1275).
–2
3.2.19 tensile strength [FL ], n—the maximum tensile stress which a material is capable of sustaining. Tensile strength is
calculated from the maximum force during a tension test carried to rupture and the original cross-sectional area of the test
specimen. (See Terminology E6.)
3.3 Definitions of Terms Specific to This Standard:
C1360 − 10 (2015)
–2
3.3.1 fracture strength [FL ], n—the tensile stress that the material sustains at the instant of fracture. Fracture strength is
calculated from the force at fracture during a tension test carried to rupture and the original cross-sectional area of the test
specimen.
3.3.1.1 Discussion—
In some cases, the fracture strength may be identical to the tensile strength if the force at fracture is the maximum for the test.
–2
3.3.2 maximum stress, S [FL ], n—the maximum applied stress during cyclic fatigue.
min
–2
3.3.3 mean stress,S [FL ], n—the difference between the mean stress and the maximum or minimum stress such that
a
S 1S
max min
S 5 (1)
m
–2]
3.3.4 minimum stress, S [FL , n—the minimum applied stress during cyclic fatigue.
min
–2]
3.3.5 stress amplitude, S [FL , n—the difference between the mean stress and the maximum stress such that
a
S 2 S
max min
S 5 5 S 2 S 5 S 2 S (2)
a max m m min
–2]
3.3.6 stress range, ΔS or S [FL , n—the difference between the maximum stress and the minimum stress such that
r
ΔS 5 S 5 S 2 S (3)
r max min
3.3.7 time to cyclic fatigue failure, t [t], n—total elapsed time from test initiation to test termination required to reach the
f
number of cycles to failure.
4. Significance and Use
4.1 This practice may be used for material development, material comparison, quality assurance, characterization, reliability
assessment, and design data generation.
4.2 Continuous fiber-reinforced ceramic matrix composites are generally characterized by crystalline matrices and ceramic fiber
reinforcements. These materials are candidate materials for structural applications requiring high degrees of wear and corrosion
resistance, and high-temperature inherent damage tolerance (that is, toughness). In addition, continuous fiber-reinforced glass
matrix composites are candidate materials for similar but possibly less-demanding applications. Although flexural test methods are
commonly used to evaluate the mechanical behavior of monolithic advanced ceramics, the non-uniform stress distribution in a
flexural test specimen in addition to dissimilar mechanical behavior in tension and compression for CFCCs leads to ambiguity of
interpretation of test results obtained in flexure for CFCCs. Uniaxially-loaded tensile tests provide information on mechanical
behavior for a uniformly stressed material.
4.3 The cyclic fatigue behavior of CFCCs can have appreciable non-linear effects (for example, sliding of fibers within the
matrix) which may be related to the heat transfer of the specimen to the surroundings. Changes in test temperature, frequency, and
heat removal can affect test results. It may be desirable to measure the effects of these variables to more closely simulate end-use
conditions for some specific application.
4.4 Cyclic fatigue by its nature is a probabilistic phenomenon as discussed in STP 91A (Ref (1)) and STP 588 (Ref (2)). In
addition,
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