ASTM C1360-17

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 nonuniform 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 nonlinear 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 (1) and STP 588 (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 (1), STP 588 (2), and Practice E739. Studies to determine the inf...
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.

General Information

• Status: Published
• Publication Date: 31-Jan-2017
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: C28 - Advanced Ceramics
• Drafting Committee: C28.07 - Ceramic Matrix Composites

Relations

• Replaces: ASTM C1360-10(2015) - Standard Practice for Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures
• Effective Date: 01-Feb-2017
• Refers: ASTM E1823-24a - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 15-Feb-2024
• Refers: ASTM E1823-24 - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 01-Feb-2024
• Refers: ASTM E1823-20 - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 01-Feb-2020
• Refers: ASTM D3878-19a - Standard Terminology for Composite Materials
• Effective Date: 15-Oct-2019
• Refers: ASTM C1145-19 - Standard Terminology of Advanced Ceramics
• Effective Date: 01-Jul-2019
• Refers: ASTM D3878-19 - Standard Terminology for Composite Materials
• Effective Date: 15-Apr-2019
• Refers: ASTM D3878-18 - Standard Terminology for Composite Materials
• Effective Date: 01-Apr-2018
• Refers: ASTM C1275-18 - Standard Test Method for Monotonic Tensile Behavior of Continuous Fiber-Reinforced Advanced Ceramics with Solid Rectangular Cross-Section Test Specimens at Ambient Temperature
• Effective Date: 01-Jan-2018
• Refers: ASTM C1275-16 - Standard Test Method for Monotonic Tensile Behavior of Continuous Fiber-Reinforced Advanced Ceramics with Solid Rectangular Cross-Section Test Specimens at Ambient Temperature
• Effective Date: 01-Dec-2016
• Refers: ASTM D3878-16 - Standard Terminology for Composite Materials
• Effective Date: 01-Aug-2016
• Refers: ASTM D3878-15 - Standard Terminology for Composite Materials
• Effective Date: 01-Jul-2015
• Refers: ASTM C1275-15 - Standard Test Method for Monotonic Tensile Behavior of Continuous Fiber-Reinforced Advanced Ceramics with Solid Rectangular Cross-Section Test Specimens at Ambient Temperature
• Effective Date: 01-Jul-2015
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014
• Refers: ASTM D3878-07(2013) - Standard Terminology for Composite Materials
• Effective Date: 01-May-2013

Overview

ASTM C1360-17, titled Standard Practice for Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures, establishes best practices and requirements for characterizing the tension-tension cyclic fatigue behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) at ambient temperatures. Developed by ASTM International, this standard builds upon established tensile testing methods for CFCCs, offering guidance on specimen preparation, test methods, data acquisition, and reporting, with a specific focus on constant-amplitude, uniaxial fatigue testing.

Continuous fiber-reinforced advanced ceramics exhibit properties highly sought after in structural applications requiring outstanding wear, corrosion resistance, and damage tolerance at elevated temperatures. ASTM C1360-17 facilitates reliable comparison, material development, quality control, and design data generation for these advanced materials.

Key Topics

• Applicable Materials:
  • Continuous fiber-reinforced ceramic matrix composites (uni-directional, bi-directional, tri-directional, or other multidirectional reinforcements)
  • Continuous fiber-reinforced glass matrix composites with similar reinforcement architecture
  • The standard is not explicitly intended for discontinuous fiber-, whisker-, or particulate-reinforced ceramics, though methods may be applicable in those cases.
• Test Types and Conditions:
  • Constant-amplitude, axial, tension-tension cyclic fatigue testing
  • Controlled environmental and operational parameters: temperature, humidity, testing frequency, and force ratios
  • Guidance on allowable specimen bending and necessary statistical sampling for probabilistic fatigue behavior evaluation
• Specimen Handling and Preparation:
  • Methods for specimen fabrication and handling to prevent introduction of random or severe flaws
  • Recommendations for test geometry, surface preparation, and pre-test storage to maintain consistency and reliability in test results
• Significance of Uniform Stress:
  • Emphasizes the importance of uniaxial tensile tests (as opposed to flexural tests) due to the uniform stress distribution and avoidance of ambiguity in interpreting fatigue behavior
• Cyclic Fatigue as a Probabilistic Phenomenon:
  • Recognizes the inherent variability in cyclic fatigue data and provides references for statistical analysis to ensure robust design and material characterization

Applications

ASTM C1360-17 is essential for organizations and researchers working with advanced ceramic matrix composites in sectors including:

• Aerospace and Defense:
  Structural components subject to repeated mechanical loads, where lightweight, high-strength, and damage-tolerant materials are needed.
• Energy and Industrial Systems:
  Turbine, boiler, and heat exchanger components, where wear, corrosion resistance, and high-temperature performance are vital.
• Automotive and Transportation:
  Advanced engine components and brake systems demanding cyclic durability under mechanical stress.
• Material Development and Quality Assurance:
  Comparing new material formulations, assessing production consistency, and establishing design criteria based on reliable cyclic fatigue data.
• Research and Development:
  Academic or corporate materials labs generating fatigue data for theoretical modeling, failure prediction, or new composite systems.

The practice stipulated by ASTM C1360-17 ensures that data generated is consistent, statistically robust, and suitable for critical design decisions and comparative studies.

Related Standards

ASTM C1360-17 references and complements several other important ASTM standards and terminology documents, including:

• ASTM C1275: Test Method for Monotonic Tensile Behavior of Continuous Fiber-Reinforced Advanced Ceramics
• ASTM E4: Practices for Force Verification of Testing Machines
• ASTM E83: Practice for Verification and Classification of Extensometer Systems
• ASTM E467: Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
• ASTM E739: Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
• ASTM C1145, D3479/D3479M, D3878, E6, E1012, E1823: Key terminology and related testing methods for advanced ceramics and composite materials

For further reliability and comprehensive assessment, practitioners are encouraged to consult referenced documents and applicable sector-specific regulations. Compliance with ASTM C1360-17 helps ensure accuracy, repeatability, and industry acceptance of cyclic fatigue testing for advanced ceramic composites.

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: C1360 − 17
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 [e-mail]. For Annual Book of ASTM
Matrix Composites. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Feb. 1, 2017. Published February 2017. Originally the ASTM website.
approved in 1996. Last previous edition approved in 2015 as C1360 – 10 (2015). The last approved version of this historical standard is referenced on
DOI: 10.1520/C1360-17. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1360 − 17
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 not 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 Terminology C1145.)
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, N 10 –10 ). (See Termi- deviationfromproportionalityofstresstostrain(Hooke’slaw).
f
nology E1823.) (See Terminology E6.)
C1360 − 17
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 nonuniform 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—subcritical crack growth (ex-
uniformly stressed material.
tension) 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 Terminology C1145.) ciable nonlinear 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
enon as discussed in STP 91A (1) and STP 588 (2). In
material sustains at the instant of fracture. Fracture strength is
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 (1), STP 588 (2), and Practice
may be identical to the tensile strength if the force at fracture
E739. Studies to determine the influence of test specimen
is the maximum for the test.
volume or surface area on cyclic fatigue strength distributions
–2
3.3.2 maximum stress, S [FL ], n—the maximum ap-
max for CFCCs have not been completed. The many different
plied stress during cyclic fatigue.
tensile test specimen geometries available for cyclic fatigue
–2
testing may result in variations in the measured cyclic fatigue
3.3.3 mean stress, S [FL ], n—the difference between the
m
behavior of a particular material due to differences in the
mean stress and the maximum or minimum stress such that
volume of material in the gage section of the test specimens.
S 1S
max min
S 5 (1)
m
4.5 Tensile cyclic fatigue tests provide information on the
material response under fluctuating uniaxial tensile stresses.
–2
3.3.4 minimum stress, S [FL ], n—the minimum applied
min
Uniform stress states are required to effectively evaluate any
stress during cyclic fatigue.
nonlinear stress-strain behavior which may develop as the
–2
3.3.5 stress amplitude, S [FL ], n—the difference between
a result of cumulative damage processes (for example, matrix
the mean stress and the maximum stress such that
microcracking, fiber/matrix debonding, delamination, cyclic
fatigue crack growth, etc.)
S 2 S
max min
S 5 5 S 2 S 5 S 2 S (2)
a max m m min
4.6 Cumulative damage due to cyclic fatigue may be influ-
–2
enced by testing mode, testing rate (related to frequency),
3.3.6 stress range, ∆SorS [FL ], n—the difference be-
r
differences between maximum and minimum force (R or Α),
tween the maximum stress and the minimum stress such that
effects of processing or combinations of constituent materials,
∆S 5 S 5 S 2 S (3)
r max min
3.3.7 time to cyclic fatigue failure, t [t], n—total elapsed
f
timefromtestinitiationtotestterminationrequiredtoreachthe
The boldface numbers in parentheses refer to a list of references at the end of
number of cycles to failure. this standard.
C1360 − 17
environmental influences (including test environment and pre- composite leading to rapid cyclic fatigue failures. Conversely,
test conditioning), or combinations thereof. Some of these low testing rates (that is, low frequency or wave forms with
effects may be consequences of stress corrosion or subcritical plateaus) may serve to promote environmental degradation as
(slow) crack growth which can be difficult to quantify. Other the material is exposed to maximum tensile stresses for longer
factorswhichmayinfluencecyclicfatiguebehaviorare:matrix periods of time.
or fiber material, void or porosity content, methods of test
5.3 In many materials, amplitude of the cyclic wave form is
specimen preparation or fabrication, volume percent of the
a primary contributor to the cyclic fatigue behavior. Thus,
reinforcement, orientation and stacking of the reinforcement,
choice of force ratio, R or Α, can have a pronounced effect on
test specimen conditioning, test environment, force or strain
the cyclic fatigue behavior of the material.Aforce ratio of R =
limits during cycling, wave shapes (that is, sinusoidal,
1 (that is, maximum equal to minimum) constitutes a constant
trapezoidal, etc.), and failure mode of the CFCC.
force test with no fluctuation of force over time. A force ratio
4.7 The results of cyclic fatigue tests of test specimens
of R = 0 (that is, minimum force equal to zero) constitutes the
fabricated to standardized dimensions from a particular mate-
maximum amplitude (that is, amplitude equal to one-half the
rial or selected portions of a part, or both, may not totally
maximum) for tension-tension cyclic fatigue.Aforce ratio of R
represent the cyclic fatigue behavior of the entire, full-size end
= 0.1 is often chosen for tension-tension cyclic fatigue so as to
product or its in-service behavior in different environments.
impose maximum amplitudes while minimizing the possibility
of a “slack” (that is, loose and non-tensioned) load train. The
4.8 However, for quality control purposes, results derived
choice of R or Α is dictated by the final use of the test result.
from standardized tensile test specimens may be considered
indicativeoftheresponseofthematerialfromwhichtheywere
5.4 Surface preparation of test specimens, although nor-
taken for given primary processing conditions and post-
mally not considered a major concern in CFCCs, can introduce
processing heat treatments.
fabrication flaws which may have pronounced effects on cyclic
fatigue behavior (for example, shape and level of the resulting
4.9 The cyclic fatigue behavior of a CFCC is dependent on
stress-strain curves, cyclic fatigue limits, etc.). Machining
its inherent resistance to fracture, the presence of flaws, or
damage introduced during test specimen preparation can be
damage accumulation processes, or both. There can be signifi-
eitherarandominterferingfactorinthedeterminationofcyclic
cant damage in the CFCC test specimen without any visual
fatigue or ultimate strength of pristine material (that is, more
evidence such as the occurrence of a macroscopic crack. This
frequent occurrence of surface-initiated fractures compared to
can result in a loss of stiffness and retained strength. Depend-
volume-initiated fractures), or an inherent part of the strength
ing on the purpose for which the test is being conducted, rather
characteristics to be measured. Surface preparation can also
than final fracture, a specific loss in stiffness or retained
lead to the introduction of residual stresses. Universal or
strength may constitute failure. In cases where fracture occurs,
standardized methods for surface preparation do not exist. In
analysis of fracture surfaces and fractography, though beyond
addition, the nature of fabrication used for certain composites
the scope of this practice, is recommended.
(for example, chemical vapor infiltration or hot pressing) may
require the testing of specimens in the as-processed condition
5. Interferences
(that is, it may not be possible to machine the test specimen
5.1 Test environment (for example, vacuum, inert gas,
faces without compromising the in-plane fiber architecture).
ambient air, etc.) including moisture content (for example,
Note that final machining steps may, or may not, negate
relative humidity) may have an influence on the measured
machining damage introduced during the initial machining.
cyclic fatigue behavior. In particular, the behavior of materials
Thus, report test specimen fabrication history since it may play
susceptible to slow crack growth fracture will be strongly
an important role in the cyclic fatigue behavior.
influenced by test environment and testing rate. Conduct tests
5.5 Bending in uniaxial tensile tests can cause or promote
to evaluate the maximum strength potential of a material in
nonuniform stress distributions with maximum stresses occur-
inert environments or at sufficiently rapid testing rates, or both,
ring at the test specimen surface leading to nonrepresentative
to minimize slow crack growth effects. Conversely, conduct
fracturesoriginatingatsurfacesorneargeometricaltransitions.
tests in environments or at test modes, or both, and rates
In addition, if deformations or strains are measured at surfaces
representative of service conditions to evaluate material per-
where maximum or minimum stresses occur, bending may
formance under use conditions. Regardless of whether testing
introduce over or under measurement of strains depending on
is conducted in uncontrolled ambient air or controlled
the location of the strain-measuring device on the test speci-
environments, monitor and report relative humidity and tem-
men.Similarly,fracturefromsurfaceflawsmaybeaccentuated
perature at a minimum at the beginning and end of each test,
or suppressed by the presence of the nonuniform stresses
and hourly (if possible) if the test duration is greater than 1 h.
caused by bending.
Testing at humidity levels greater than 65 % relative humidity
(RH) is not recommended.
5.6 Fractures that initiate outside the uniformly stressed
5.2 RateeffectsinmanyCFCCsmayplayimportantrolesin gage section of a test specimen may be due to factors such as
degrading cyclic fatigue performance. In particular, high test- stress concentrations or geometrical transitions, extraneous
ing rates (that is, high frequency) may cause localized heating stresses introduced by gripping, or strength-limiting features in
due to frictional sliding of debonded fibers within the matrix. the microstructure of the test specimen. Such non-gage section
Such sliding may accelerate mechanical degradation of the fractures will normally constitute invalid tests. In addition, for
C1360 − 17
face-forced geometries, gripping pressure is a key variable in analog chart recorder or plotter in conjunction with the digital
the initiation of fracture. Insufficient pressure can shear the data acquisition system to provide an immediate record of the
outer plies in laminated CFCCs, while too much pressure can test as a supplement to the digital record. Recording devices
cause local crushing of the CFCC and may initiate fracture in shallbeaccurateto1.0%oftherecordingrangeandshallhave
the vicinity of the grips. minimum data sampling and acquisition rates sufficient to
adequately describe the loading cycle (for example, ;100 data
6. Apparatus
points per cycle).
6.1 Tensile Testing Machines—Machines used for determin-
6.7 Dimension-Measuring Devices—Micrometers and other
ing proportional limit stress, ultimate strength or other “static”
devices used for measuring linear dimensions shall be accurate
material properties shall conform to Practices E4. Machines
and precise to at least one-half the smallest unit to which the
used for cyclic fatigue testing may be either nonresonant
individual dimension is required to be measured. Measure
mechanical, hydraulic, or magnetic systems or resonant type
cross-sectional dimensions to within 0.02 mm using
using forced vibration excited by magnetic or centrifugal force
dimension-measuring devices with accuracies of 0.01 mm.
and shall conform to Practice E467.
6.8 Temperature Measurement—Cyclic fatigue tests may be
6.2 Gripping Devices—Devices used to grip the test speci-
run at high cyclic frequencies (>50 Hz) that can cause internal
mens may be of the types discussed in 6.2 of Test Method
heating of the test specimen thereby affecting the cyclic fatigue
C1275 as long as they meet the requirements of this practice
life especially in the case of debonded and sliding fibers
...

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 (Reapproved 2015) C1360 − 17
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*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 1, 2015Feb. 1, 2017. Published September 2015February 2017. Originally approved in 1996. Last previous edition approved in 20102015
as C1360 – 10.C1360 – 10 (2015). DOI: 10.1520/C1360-10R15.10.1520/C1360-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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 − 17
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 nonnot 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
Terminology C1275C1145.)
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 − 17
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, NfN 10 – 10 ). (See Terminology E1823.)
f
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
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
~ !
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-criticalsubcritical crack growth (extension) that may result from, but is not restricted to, such
mechanisms as environmentally-assisted environmentally assisted stress corrosion or diffusive crack growthgrowth. (See Test
Method Terminology C1275C1145).)
C1360 − 17
–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:
–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.
minmax
–2
3.3.3 mean stress,Sstress, S [FL ], n—the difference between the mean stress and the maximum or minimum stress such that
am
S 1S
max min
S 5 (1)
m
–2]–2
3.3.4 minimum stress, S [FL ,], n—the minimum applied stress during cyclic fatigue.
min
–2]–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] –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 less demanding applications. Although flexural
test methods are commonly used to evaluate the mechanical behavior of monolithic advanced ceramics, the non-
uniformnonuniform 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
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-linearnonlinear 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, 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. Studies to determine the influence of test specimen volume or
surface area on cyclic fatigue strength distributions for CFCCs have not been completed. The many different tensile test specimen
geometries available for cyclic fatigue testing may result in variations in the measured cyclic fatigue behavior of a particular
material due to differences in the volume of material in the gage section of the test specimens.
4.5 Tensile cyclic fatigue tests provide information on the material response under fluctuating uniaxial tensile stresses. Uniform
stress states are required to effectively evaluate any nonlinear stress-strain behavior which may develop as the result of cumulative
damage processes (for example, matrix microcracking, fiber/matrix debonding, delamination, cyclic fatigue crack growth, etc.)
4.6 Cumulative damage due to cyclic fatigue may be influenced by testing mode, testing rate (related to frequency), differences
between maximum and minimum force(force (R or Α), effects of processing or combinations of constituent materials, and/or
The boldface numbers in parentheses refer to a list of references at the end of this standard.
C1360 − 17
environmental influences (including test environment and pre-test conditioning), or both. combinations thereof. Some of these
effects may be consequences of stress corrosion or sub critical subcritical (slow) crack growth which can be difficult to quantify.
Other factors which may influence cyclic fatigue behavior are: matrix or fiber material, void or porosity content, methods of test
specimen preparation or fabrication, volume percent of the reinforcement, orientation and stacking of the reinforcement, test
specimen conditioning, test environment, force or strain limits during cycling, wave shapes (that is, sinusoidal, trapezoidal, etc.),
and failure mode of the CFCC.
4.7 The results of cyclic fatigue tests of test specimens fabricated to standardized dimensions from a particular material or
selected portions of a part, or both, may not totally represent the cyclic fatigue behavior of the entire, full-size end product or its
in-service behavior in different environments.
4.8 However, for quality control purposes, results derived from standardized tensile 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.
4.9 The cyclic fatigue behavior of a CFCC is dependent on its inherent resistance to fracture, the presence of flaws, or damage
accumulation processes, or both. There can be significant damage in the CFCC test specimen without any visual evidence such
as the occurrence of a macroscopic crack. This can result in a loss of stiffness and retained strength. Depending on the purpose
for which the test is being conducted, rather than final fracture, a specific loss in stiffness or retained strength may constitute failure.
In cases where fracture occurs, analysis of fracture surfaces and fractography, though beyond the scope of this practice, is
recommended.
5. Interferences
5.1 Test environment (vacuum, (for example, vacuum, inert gas, ambient air, etc.) including moisture content (for example,
relative humidity) may have an influence on the measured cyclic fatigue behavior. In particular, the behavior of materials
susceptible to slow crack growth fracture will be strongly influenced by test environment and testing rate. Conduct tests to evaluate
the maximum strength potential of a material in inert environments or at sufficiently rapid testing rates, or both, to minimize slow
crack growth effects. Conversely, conduct tests in environments or at test modes, or both, and rates representative of service
conditions to evaluate material performance under use conditions. Regardless of whether testing is conducted in uncontrolled
ambient air or controlled environments, monitor and report relative humidity and temperature at a minimum at the beginning and
end of each test, and hourly (if possible) if the test duration is greater than 1 h. Testing at humidity levels greater than 65 % relative
humidity (RH) is not recommended.
5.2 Rate effects in many CFCCs may play important roles in degrading cyclic fatigue performance. In particular, high testing
rates (that is, high frequency) may cause localized heating due to frictional sliding of debonded fibers within the matrix. Such
sliding may accelerate mechanical degradation of the composite leading to rapid cyclic fatigue failures. Conversely, low testing
rates (that is, low frequency or wave forms with plateaus) may serve to promote environmental degradation as the material is
exposed to maximum tensile stresses for longer periods of time.
5.3 In many materials, amplitude of the cyclic wave form is a primary contributor to the cyclic fatigue behavior. Thus, choice
of force ratio, R or Α, can have a pronounced effect on the cyclic fatigue behavior of the material. A force ratio of R = 1 (that is,
maximum equal to minimum) constitutes a constant force test with no fluctuation of force over time. A force ratio of R = 0 (that
is, minimum force equal to zero) constitutes the maximum amplitude (that is, amplitude equal to one half one-half the maximum)
for tension-tension cyclic fatigue. A force ratio of R = 0.1 is often chosen for tension-tension cyclic fatigue so as to impose
maximum amplitudes while minimizing the possibility of a “slack” (that is, loose and non-tensioned) forceload train. The choice
of R or Α is dictated by the final use of the test result.
5.4 Surface preparation of test specimens, although normally not considered a major concern in CFCCs, can introduce
fabrication flaws which may have pronounced effects on cyclic fatigue behavior (for example, shape and level of the resulting
stress-strain curves, cyclic fatigue limits, etc.). Machining damage introduced during test specimen preparation can be either a
random interfering factor in the determination of cyclic fatigue or ultimate strength of pristine material (that is, more frequent
occurrence of surface-initiated fractures compared to volume-initiated fractures), or an inherent part of the strength characteristics
to be measured. Surface preparation can also lead to the introduction of residual stresses. Universal or standardized methods for
surface preparation do not exist. In addition, the nature of fabrication used for certain composites (for example, chemical vapor
infiltration or hot pressing) may require the testing of specimens in the as-processed condition (that is, it may not be possible to
machine the test specimen faces without compromising the in-plane fiber architecture). Note that final machining steps may, or may
not, negate machining damage introduced during the initial machining. Thus, report test specimen fabrication history since it may
play an important role in the cyclic fatigue behavior.
5.5 Bending in uniaxial tensile tests can cause or promote non-uniformnonuniform stress distributions with maximum stresses
occurring at the test specimen surface leading to non-representativenonrepresentative fractures originating at surfaces or near
geometrical transitions. In addition, if deformations or strains are measured at surfaces where maximum or minimum stresses
occur, bending may introduce over or under measurement of strains depending on the location of the strain-measuring device on
C1360 − 17
the test specimen. Similarly, fracture from surface flaws may be accentuated or suppressed by the presence of the
non-uniformnonuniform stresses caused by bending.
5.6 Fractures that initiate outside the uniformly-stressed uniformly stressed gage section of a test specimen may be due to factors
such as stress concentrations or geometrical transitions, extraneous stresses introduced by gripping, or strength-limiting features
in the microstructure of the test specimen. Such non-gage section fractures will normally constitute invalid tests. In addition, for
face-forced geometries, gripping pressure is a key variable in the initiation of fracture. Insufficient pressure can shear the outer plies
in laminated CFCCs;CFCCs, while too much pressure can cause local crushing of the CFCC and may initiate fracture in the
vicinity of the grips.
6. Apparatus
6.1 Tensile Testing Machines—Machines used for determining proportional limit stress, ultimate strength or other “static”
material properties shall conform to Practices E4. Machines used for cyclic fatigue testing may be either nonresonant mechanical,
hydraulic, or magnetic systems or resonant type using forced vibration excited by magnetic or centrifugal force and shall conform
to Practice E467.
6.2 Gripping Devices—Devices used to grip the test specimens may be of the types discussed in 6.2 of Test Method C1275 as
long as they meet the requirements of this practice and Test Method C1275.
6.3 Load Train Couplers—Devices used to align the load train and to act as an interface between the gripping devices and the
testing machine may be of the types discussed in 6.3 of Test Method C1275 as long as they meet the requirements of this practice
and Test Method C1275.
6.4 Strain Measurement—Determine strain by means of either a suitable extensometer or strain gages as discussed in Test
Method C1275. Extensometers shall satisfy Practice E83, Class B-1 requirements and are recommended instead of strain gages
for test specimens with gage lengths of ≥25 mm. Calibrate extensometers periodically in accordance with Practice E83.
6.5 Allowable Bending—Analytical and empirical studies of the effect of bending on the cyclic fatigue behaviourbehavior of
CFCCs do not exist. Until such information is forthcoming for CFCCs, this practice adopts the recommendations of Test Method
C1275. However, note that unless all test specimens are properly strain gaged and percent bending is monitored during testing,
there will be no record of percent bending for each test specimen. Therefore, verify the testing s
...