ASTM C1275-00

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Designation:C 1275–00
Standard Test Method for
Monotonic Tensile Behavior of Continuous Fiber-Reinforced
Advanced Ceramics with Solid Rectangular Cross-Section
Test Specimens at Ambient Temperature
This standard is issued under the fixed designation C 1275; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of tensile 2.1 ASTM Standards:
behavior including tensile strength and stress-strain response C1145 Terminology of Advanced Ceramics
under monotonic uniaxial loading of continuous fiber- C1239 Practice for Reporting Uniaxial Strength Data and
reinforcedadvancedceramicsatambienttemperature.Thistest Estimating Weibull Distribution Parameters for Advanced
method addresses, but is not restricted to, various suggested Ceramics
test specimen geometries as listed in the appendix. In addition, D3039/D3039M Test Method for Tensile Properties of
specimen fabrication methods, testing modes (force, displace- Polymer Matrix Composite Materials
ment, or strain control), testing rates (force rate, stress rate, D3379 Test Method for Tensile Strength and Young’s
displacement rate, or strain rate), allowable bending, and data Modulus for High-Modulus Single-Filament Materials
collection and reporting procedures are addressed. Note that D3878 Terminology of High-Modulus Reinforcing Fibers
tensile strength as used in this test method refers to the tensile and Their Composites
strength obtained under monotonic uniaxial loading where E4 Practices for Force Verification of Testing Machines
monotonic refers to a continuous nonstop test rate with no E6 Terminology Relating to Methods of Mechanical Test-
reversals from test initiation to final fracture. ing
1.2 This test method applies primarily to all advanced E83 Practice for Verification and Classification of Exten-
ceramic matrix composites with continuous fiber reinforce- someters
ment: uni-directional (1-D), bi-directional (2-D), and tri- E177 Practice for Use of the Terms Precision and Bias in
directional (3-D). In addition, this test method may also be ASTM Test Methods
usedwithglass(amorphous)matrixcompositeswith1-D,2-D, E337 Test Method for Measuring Humidity with Psy-
and 3-D continuous fiber reinforcement.This test method does chrometer (the Measurement of Wet- and Dry-Bulb Tem-
not address directly discontinuous fiber-reinforced, whisker- peratures)
reinforced or particulate-reinforced ceramics, although the test E380 PracticeforUseofInternationalSystemofUnits(SI)
methods detailed here may be equally applicable to these (the Modernized Metric System)
composites. E691 Practice for Conducting an Interlaboratory Study to
1.3 Values expressed in this test method are in accordance Determine the Precision of a Test Method
withtheInternationalSystemofUnits(SI)andPracticeE380. E1012 Practice for Verification of Specimen Alignment
1.4 This standard does not purport to address all of the Under Tensile Loading
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 3.1 Definitions—The definitions of terms relating to tensile
testingappearinginTerminologyE6applytothetermsusedin
bility of regulatory limitations prior to use. Specific hazard
statements are given in Section 7 and Note 1. this test method. The definitions of terms relating to advanced
Annual Book of ASTM Standards, Vol 15.01.
1 3
This practice is under the jurisdiction ofASTM Committee C-28 onAdvanced Annual Book of ASTM Standards, Vol 15.03.
Ceramicsand is the direct responsibility of Subcommittee C28.07 on Ceramic Annual Book of ASTM Standards, Vol 03.01.
Matrix Composites. Annual Book of ASTM Standards, Vol 14.02.
Current edition approved June 10, 2000. Published August 2000. Originally Annual Book of ASTM Standards, Vol 11.03.
published as C1275–94. Last previous edition C1275–95. Discontinued 1997—Replaced by IEEE/ASTM SI-10.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1275–00
ceramics appearing in Terminology C1145 apply to the terms 3.1.12 modulusoftoughness—strainenergyperunitvolume
used in this test method. The definitions of terms relating to required to stress the material from zero to final fracture
fiber reinforced composites appearing in Terminology D3878 indicating the ability of the material to absorb energy beyond
applytothetermsusedinthistestmethod.Pertinentdefinitions the elastic range (that is, damage tolerance of the material).
aslistedinPracticeE1012,TerminologyC1145,Terminology 3.1.13 Discussion— The modulus of toughness can also be
D3878, and Terminology E6 are shown in the following with referred to as the cumulative damage energy and as such is
the appropriate source given in parentheses. Additional terms regardedasanindicationoftheabilityofthematerialtosustain
used in conjunction with this test method are defined in the damage rather than as a material property. Fracture mechanics
following: methods for the characterization of CFCCs have not been
3.1.1 advanced ceramic, n—a highly engineered, high per- developed. The determination of the modulus of toughness as
provided in this test method for the characterization of the
formance predominantly nonmetallic, inorganic, ceramic ma-
terial having specific functional attributes. (See Terminology cumulative damage process in CFCCs may become obsolete
when fracture mechanics methods for CFCCs become avail-
C1145.)
able.
3.1.2 axial strain—the average longitudinal strains mea-
3.1.14 proportional limit stress— the greatest stress that a
sured at the surface on opposite sides of the longitudinal axis
material is capable of sustaining without any deviation from
of symmetry of the specimen by two strain-sensing devices
proportionality of stress to strain (Hooke’s law).
located at the mid length of the reduced section. (See Practice
3.1.15 Discussion—Many experiments have shown that
E1012.)
valuesobservedfortheproportionallimitvarygreatlywiththe
3.1.3 bending strain—the difference between the strain at
sensitivity and accuracy of the testing equipment, eccentricity
the surface and the axial strain. In general, the bending strain
of loading, the scale to which the stress-strain diagram is
variesfrompointtopointaroundandalongthereducedsection
plotted, and other factors. When determination of proportional
of the specimen. (See Practice E1012.)
limit is required, the procedure and sensitivity of the test
3.1.4 breaking force—the force at which fracture occurs.
equipment should be specified. (See Terminology E6.)
(See Terminology E6.)
3.1.16 percent bending—The bending strain times 100
3.1.5 ceramic matrix composite—a material consisting of
divided by the axial strain. (See Practice E1012.)
two or more materials (insoluble in one another), in which the
3.1.17 slow crack growth—subcritical crack growth (exten-
major,continuouscomponent(matrixcomponent)isaceramic,
sion) which may result from, but is not restricted to, such
whilethesecondarycomponent/s(reinforcingcomponent)may
mechanisms as environmentally-assisted stress corrosion or
be ceramic, glass-ceramic, glass, metal or organic in nature.
diffusive crack growth.
These components are combined on a macroscale to form a
3.1.18 tensilestrength—themaximumtensilestresswhicha
useful engineering material possessing certain properties or
material is capable of sustaining. Tensile strength is calculated
behavior not possessed by the individual constituents.
fromthemaximumloadduringatensiontestcarriedtorupture
3.1.6 continuous fiber-reinforced ceramic matrix composite
and the original cross-sectional area of the specimen. (See
(CFCC)—aceramicmatrixcompositeinwhichthereinforcing
Terminology E6.)
phase consists of a continuous fiber, continuous yarn, or a
woven fabric.
4. Significance and Use
3.1.7 gage length—the original length of that portion of the
4.1 Thistestmethodmaybeusedformaterialdevelopment,
specimen over which strain or change of length is determined.
material comparison, quality assurance, characterization, and
(See Terminology E6.)
design data generation.
3.1.8 matrix-cracking stress—the applied tensile stress at
4.2 Continuous fiber-reinforced ceramic matrix composites
whichthematrixcracksintoaseriesofroughlyparallelblocks
generally characterized by fine grain sized (<50 µm) matrices
normal to the tensile stress.
and ceramic fiber reinforcements are candidate materials for
3.1.9 Discussion—Insomecases,thematrixcrackingstress
structural applications requiring high degrees of wear and
may be indicated on the stress-strain curve by deviation from
corrosion resistance, and high-temperature inherent damage
linearity (proportional limit) or incremental drops in the stress
tolerance (that is, toughness). In addition, continuous fiber-
with increasing strain. In other cases, especially with materials
reinforced glass (amorphous) matrix composites are candidate
whichdonotpossessalinearportionofthestress-straincurve,
materials for similar but possibly less-demanding applications.
thematrixcrackingstressmaybeindicatedasthefirststressat
Although flexural test methods are commonly used to evaluate
which a permanent offset strain is detected in the unloading
strengths of monolithic advanced ceramics, the non-uniform
stress-strain (elastic limit).
stress distribution of the flexure specimen in addition to
3.1.10 modulus of elasticity—the ratio of stress to corre-
dissimilar mechanical behavior in tension and compression for
spondingstrainbelowtheproportionallimit.(SeeTerminology
CFCCs lead to ambiguity of interpretation of strength results
E6.)
obtained from flexure tests for CFCCs. Uniaxial-loaded tensile
3.1.11 modulus of resilience—strain energy per unit vol- strength tests provide information on mechanical behavior and
ume required to elastically stress the material from zero to the strength for a uniformly-stressed material.
proportional limit indicating the ability of the material to 4.3 Unlike monolithic advanced ceramics which fracture
absorb energy when deformed elastically and return it when catastrophicallyfromasingledominantflaw,CFCCsgenerally
unloaded. experience “graceful” fracture from a cumulative damage
C 1275–00
process. Therefore, the volume of material subjected to a >65% relative humidity (RH) is not recommended and any
uniform tensile stress for a single uniaxially-loaded tensile test deviations from this recommendation must be reported.
may not be as significant a factor in determining the ultimate 5.2 Surface preparation of test specimens, although nor-
strengths of CFCCs. However, the need to test a statistically mallynotconsideredamajorconcerninCFCCs,canintroduce
significant number of tensile specimens is not obviated.There- fabrication flaws that may have pronounced effects on tensile
fore, because of the probabilistic nature of the strength distri- mechanical properties and behavior (for example, shape and
butionsofthebrittlematricesofCFCCs,asufficientnumberof level of the resulting stress-strain curve, tensile strength and
specimens at each testing condition is required for statistical strain, proportional limit stress and strain, etc.). Machining
analysisanddesign.Studiestodeterminetheexactinfluenceof damage introduced during specimen preparation can be either
specimenvolumeonstrengthdistributionsforCFCCshavenot a random interfering factor in the determination of ultimate
been completed. It should be noted that tensile strengths strength of pristine material (that is, increased frequency of
obtained using different recommended tensile specimens with surface initiated fractures compared to volume initiated frac-
different volumes of material in the gage sections may be tures), or an inherent part of the strength characteristics to be
different due to these volume differences. measured.Surfacepreparationcanalsoleadtotheintroduction
of residual stresses. Universal or standardized test methods of
4.4 Tensile tests provide information on the strength and
surface preparation do not exist. It should be understood that
deformation of materials under uniaxial tensile stresses. Uni-
final machining steps may, or may not negate machining
form stress states are required to effectively evaluate any
damage introduced during the initial machining. Thus, speci-
non-linear stress-strain behavior which may develop as the
men fabrication history may play an important role in the
result of cumulative damage processes (for example, matrix
measured strength distributions and should be reported. In
cracking, matrix/fiber debonding, fiber fracture, delamination,
addition, the nature of fabrication used for certain composites
etc.) which may be influenced by testing mode, testing rate,
(for example, chemical vapor infiltration or hot pressing) may
processing or alloying effects, or environmental influences.
require the testing of test specimens in the as-processed
Some of these effects may be consequences of stress corrosion
condition (that is, it may not be possible to machine the
or subcritical (slow) crack growth that can be minimized by
specimen faces).
testingatsufficientlyrapidratesasoutlinedinthistestmethod.
5.3 Bending in uniaxial tensile tests can cause or promote
4.5 The results of tensile tests of test specimens fabricated
non-uniformstressdistributionswithmaximumstressesoccur-
to standardized dimensions from a particular material or
ring at the specimen surface leading to non-representative
selected portions of a part, or both, may not totally represent
fracturesoriginatingatsurfacesorneargeometricaltransitions.
the strength and deformation properties of the entire, full-size
In addition, if deformations or strains are measured at surfaces
end product or its in-service behavior in different environ-
where maximum or minimum stresses occur, bending may
ments.
introduce over or under measurement of strains depending on
4.6 For quality control purposes, results derived from stan-
the location of the strain-measuring device on the specimen.
dardizedtensiletestspecimensmaybeconsideredindicativeof
Similarly, fracture from surface flaws may be accentuated or
the response of the material from which they were taken for,
suppressed by the presence of the non-uniform stresses caused
given primary processing conditions and post-processing heat
by bending.
treatments.
5.4 Fractures that initiate outside th
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