ASTM C1361-96(2001)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: C 1361 – 96 (Reapproved 2001)
Standard Practice for
Constant-Amplitude, Axial, Tension-Tension Cyclic Fatigue
of Advanced Ceramics at Ambient Temperatures
This standard is issued under the fixed designation C 1361; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope C 1322 Practice for Fractography and Characterization of
Fracture Origins in Advanced Ceramics
1.1 This practice covers the determination of constant-
E 4 Practices for Force Verification of Testing Machines
amplitude, axial tension-tension cyclic fatigue behaviour and
E 6 Terminology Relating to Methods of Mechanical Test-
performance of advanced ceramics at ambient temperatures to
ing
establish “baseline” cyclic fatigue performance. This practice
E 83 Practice for Verification and Classification of Exten-
builds on experience and existing standards in tensile testing
someters
advanced ceramics at ambient temperatures and addresses
E 337 Test Method for Measured Humidity with Psychrom-
various suggested test specimen geometries, specimen fabrica-
eter (the Measurement of Wet-and Dry-Bulb Tempera-
tion methods, testing modes (load, displacement, or strain
tures)
control), testing rates and frequencies, allowable bending, and
E 380 Standard for Use of International System of Units
procedures for data collection and reporting. This practice does
(SI) (the Modern Metric System)
not apply to axial cyclic fatigue tests of components or parts
E 467 Practice for Verification of Constant Amplitude Dy-
(that is, machine elements with non uniform or multiaxial
namic Forcesin an Axial Fatigue Testing System
stress states).
E 468 Practice for Presentation of Constant Amplitude Fa-
1.2 This practice applies primarily to advanced ceramics
tigue Test Results for Metallic Materials
that macroscopically exhibit isotropic, homogeneous, continu-
E 739 Practice for Statistical Analysis of Linear or Linear-
ous behaviour. While this practice applies primarily to mono-
ized Stress-Life (S-N) and Strain-Life (e-N) Fatigue Data
lithic advanced ceramics, certain whisker- or particle-
E 1012 Practice for Verification of Specimen Alignment
reinforced composite ceramics as well as certain discontinuous
Under Tensile Loading
fibre-reinforced composite ceramics may also meet these
E 1150 Definitions of Terms Relating to Fatigue
macroscopic behaviour assumptions. Generally, continuous
2.2 Military Handbook:
fibre-reinforced ceramic composites (CFCCs) do not macro-
MIL-HDBK-790 Fractography and Characterization of
scopically exhibit isotropic, homogeneous, continuous behav-
Fracture Origins in Advanced Structural Ceramics
iour and application of this practice to these materials is not
recommended.
3. Terminology
1.3 The values stated in SI units are to be regarded as the
3.1 Definitions—Definitions of terms relating to advanced
standard and are in accordance with Practice E 380.
ceramics, cyclic fatigue, and tensile testing as they appear in
1.4 This standard does not purport to address all of the
Terminology C 1145, Definitions E 1150, and Terminology
safety concerns, if any, associated with its use. It is the
E 6, respectively, apply to the terms used in this practice.
responsibility of the user of this standard to establish appro-
Selected terms with definitions follow with the appropriate
priate safety and health practices and determine the applica-
source given in parenthesis. Additional terms are also defined
bility of regulatory limitations prior to use. Refer to Section 7
in 3.2.
for specific precautions.
3.2 Definitions of Terms Specific to This Standard:
2. Referenced Documents 3.2.1 advanced ceramic, n—a highly engineered, high per-
formance predominately non-metallic, inorganic, ceramic ma-
2.1 ASTM Standards:
2 terial having specific functional attributes. (See Terminology
C 1145 Terminology on Advanced Ceramics
C 1145.)
C 1273 Test Method for Tensile Strength of Monolithic
–1
3.2.2 axial strain [LL ], n—the average longitudinal
Advanced Ceramics at Ambient Temperatures
1 3
This practice is under the jurisdiction of ASTM Committee C28 on Advanced Annual Book of ASTM Standards, Vol 3.01.
Ceramics and is the direct responsibility of Subcommittee C28.01 on Properties and Annual Book of ASTM Standards, Vol 11.03.
Performance. Annual Book of ASTM Standards, Vol 14.02.
Current edition approved Dec. 10, 1996. Published December 1997. Available from Army Research Laboratory-Materials Directorate, Aberdeen
Annual Book of ASTM Standards, Vol 15.01 Proving Ground, MD 21005.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1361
strains measured at the surface on opposite sides of the used ratios (see Definitions E 1150):
longitudinal axis of symmetry of the specimen by two strain-
minimum load valley load
R 5 or R 5
sensing devices located at the mid length of the reduced
maximum load peak load
section. (See Practice E 1012.)
and:
–1
3.2.3 bending strain [LL ], n—the difference between the
load amplitude ~maximum load – minimum load!
strain at the surface and the axial strain. In general, the bending
A5 orA5
mean load ~maximum load 1 minimum load!
strain varies from point to point around and along the reduced
–2
section of the specimen. (See Practice E 1012.)
3.2.11 maximum stress, S [FL ], n—the maximum ap-
max
3.2.4 constant amplitude loading, n—in cyclic fatigue load-
plied stress during cyclic fatigue
–2
ing, a loading in which all peak loads are equal and all of the
3.2.12 mean stress, S [FL ], n—the average applied
max
valley loads are equal. (See Definitions E 1150.)
stress during cyclic fatigue such that
3.2.5 cyclic fatigue, n—the process of progressive localized
S 1 S
max min
S 5 (1)
permanent structural change occurring in a material subjected
m
to conditions that produce fluctuating stresses and strains at
–2
3.2.13 minimum stress, S [FL ], n—the minimum ap-
min
some point or points and that may culminate in cracks or
plied stress during cyclic fatigue
complete fracture after a sufficient number of fluctuations. (See
–2
3.2.14 modulus of elasticity [FL ], n—the ratio of stress to
Definitions E 1150.) See Fig. 1 for nomenclature relevant to
corresponding strain below the proportional limit. (See Termi-
cyclic fatigue testing.
nology E 6.)
3.2.5.1 Discussion—In glass technology static tests of con-
3.2.15 percent bending, n—the bending strain times 100
siderable duration are called static fatigue tests, a type of test
divided by the axial strain. (See Practice E 1012.)
generally designated as stress-rupture.
3.2.16 S-N diagram, n—a plot of stress versus the number
3.2.5.2 Discussion—Fluctuations may occur both in load
of cycles to failure. The stress can be maximum stress, S ,
max
and with time (frequency) as in the case of random vibration.
minimum stress, S , stress range, DS or S , or stress ampli-
min r
3.2.6 cyclic fatigue life, N —the number of loading cycles of
f
tude, S . The diagram indicates the S-N relationship for a
a
a specified character that a given specimen sustains before
specified value of S , A, R and a specified probability of
m
failure of a specified nature occurs. (See Definitions E 1150.)
–2
survival. For N, a log scale is almost always used, although a
3.2.7 cyclic fatigue limit, S , [FL ], n—the limiting value of
f
linear scale may also be used. For S, a linear scale is usually
the median cyclic fatigue strength as the cyclic fatigue life, N ,
f
6 7
used, although a log scale may also be used. (See Definitions
becomes very large. (for example, N>10 -10 ). (See Defini-
E 1150 and Practice E 468.)
tions E 1150)
3.2.17 slow crack growth, n—sub-critical crack growth
3.2.7.1 Discussion—Certain materials and environments
(extension) that may result from, but is not restricted to, such
preclude the attainment of a cyclic fatigue limit. Values
mechanisms as environmentally-assisted stress corrosion or
tabulated as cyclic fatigue limits in the literature are frequently
diffusive crack growth.
(but not always) values of S at 50 % survival at N cycles of
f f
–2
3.2.18 stress amplitude, S [FL ], n—the difference be-
a
stress in which the mean stress, S , equals zero.
m
–2
tween the mean stress and the maximum or minimum stress
3.2.8 cyclic fatigue strength S , [FL ], n—the limiting
N
such that
value of the median cyclic fatigue strength at a particular cyclic
S – S
fatigue life, N . (See Definitions E 1150.)
max min
f
S 5 5 S – S 5 S – S (2)
a max m m min
3.2.9 gage length, [L], n—the original length of that portion
of the specimen over which strain or change of length is
.
determined. (See Terminology E 6.)
–2
3.2.19 stress range, DSorS [FL ],, n—the difference
r
3.2.10 load ratio, n—in cyclic fatigue loading, the algebraic
between the maximum stress and the minimum stress such that
ratio of the two loading parameters of a cycle; the most widely
DS = S = S – S
r max min
–2
3.2.20 tensile strength [FL ], n—the maximum tensile
stress which a material is capable of sustaining. Tensile
strength is calculated from the maximum load during a tension
test carried to rupture and the original cross-sectional area of
the specimen. (See Terminology E 6.)
3.2.21 time to failure, tf [t], n—total elapsed time from test
initiation to test termination required to reach the number of
cycles to failure.
4. Significance and Use
4.1 This practice may be used for material development,
material comparison, quality assurance, characterization, reli-
ability assessment, and design data generation.
4.2 High-strength, monolithic advanced ceramic materials
FIG. 1 Cyclic Fatigue Nomenclature and Wave Forms are generally characterized by small grain sizes (<50 μm) and
C 1361
bulk densities near the theoretical density. These materials are 4.8 The cyclic fatigue behavior of an advanced ceramic is
candidates for load-bearing structural applications requiring dependent on its inherent resistance to fracture, the presence of
high degrees of wear and corrosion resistance, and high- flaws, or damage accumulation processes, or both. There can
temperature strength. Although flexural test methods are com- be significant damage in the specimen without any visual
monly used to evaluate strength of advanced ceramics, the non evidence such as the occurrence of a macroscopic crack. This
uniform stress distribution in a flexure specimen limits the can result in a specific loss of stiffness and retained strength.
volume of material subjected to the maximum applied stress at Depending on the purpose for which the test is being con-
fracture. Uniaxially-loaded tensile strength tests may provide ducted, rather than final fracture, a specific loss in stiffness or
information on strength-limiting flaws from a greater volume retained strength may constitute failure. In cases where fracture
of uniformly stressed material. occurs, analysis of fracture surfaces and fractography, though
4.3 Cyclic fatigue by its nature is a probabilistic phenom- beyond the scope of this practice, are recommended.
enon as discussed in STP 91A and STP 588.(1,2) In addition,
5. Interferences
the strengths of advanced ceramics are probabilistic in nature.
5.1 Test environment (vacuum, inert gas, ambient air, etc.)
Therefore, a sufficient number of specimens at each testing
including moisture content (for example, relative humidity)
condition is required for statistical analysis and design, with
may have an influence on the measured cyclic fatigue behavior.
guidelines for sufficient numbers provided in STP 91A, (1)
In particular, the behavior of materials susceptible to slow
STP 588, (2) and Practice E 739. The many different tensile
crack growth fracture will be strongly influenced by test
specimen geometries available for cyclic fatigue testing may
environment and testing rate. Conduct tests to evaluate the
result in variations in the measured cyclic fatigue behavior of
mechanical cyclic fatigue behaviour of a material in inert
a particular material due to differences in the volume or surface
environments to minimize slow crack growth effects. Con-
area of material in the gage section of the specimens.
versely, conduct tests in environments or at test modes and
4.4 Tensile cyclic fatigue tests provide information on the
rates representative of service conditions to evaluate material
material response under fluctuating uniaxial tensile stresses.
performance under use conditions, or both. Regardless of
Uniform stress states are required to effectively evaluate any
whether testing is conducted in uncontrolled ambient air or
non-linear stress-strain behavior which may develop as the
controlled environments, monitor and report relative humidity
result of cumulative damage processes (for example, microc-
and temperature at a minimum at the beginning and end of each
racking, cyclic fatigue crack growth, etc.).
test, and hourly if the test duration is greater than 1 h. Testing
4.5 Cumulative damage processes due to cyclic fatigue may
at humidity levels greater than 65 % relative humidity (RH) is
be influenced by testing mode, testing rate (related to fre-
not recommended.
quency), differences between maximum and minimum load (R
5.2 While cyclic fatigue in ceramics is sensitive to environ-
or A), effects of processing or combinations of constituent
ment at any stress level (4) environment has been shown to
materials, or environmental influences, or both. Other factors
have a greater influence on cyclic fatigue at higher loads (that
that influence cyclic fatigue behaviour are: void or porosity
is, loads greater than the threshold for static fatigue (5)). In this
content, methods of specimen preparation or fabrication, speci-
regime, the number of cycles to failure may be influenced by
men conditioning, test environment, load or strain limits during
test frequency and wave form. Tests performed at low fre-
cycling, wave shapes (that is, sinusoidal, trapezoidal, etc.), and
quency with wave forms having plateaus may decrease the
failure mode. Some of these effects may be consequences of
cycles to failure since the material is subject to maximum
stress corrosion or sub critical (slow) crack growth which can
tensile stresses (that is, similar to static fatigue) for longer
be difficult to quantify. In addition, surface or near-surface
periods of time during each cycle. Conversely, at lower stress
flaws introduced by the specimen fabrication process (machin-
levels the cycles to failure are usually not influenced by
ing) may or may not be quantifiable by convention
...