ASTM C1425-99
(Test Method)Standard Test Method for Interlaminar Shear Strength of 1-D and 2-D Continuous Fiber-Reinforced Advanced Ceramics at Elevated Temperatures
Standard Test Method for Interlaminar Shear Strength of 1-D and 2-D Continuous Fiber-Reinforced Advanced Ceramics at Elevated Temperatures
SCOPE
1.1 This test method addresses the compression of a double-notched specimen to determine interlaminar shear strength of continuous fiber-reinforced ceramic composites (CFCCs) at elevated temperatures. Specimen preparation methods and requirements, testing modes (load or displacement control), testing rates (load rate or displacement rate), data collection, and reporting procedures are addressed.
1.2 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. Specific precautionary statements are noted in 8.1 and 8.2.
1.3 This test method is used for testing advanced ceramic or glass matrix composites with continuous fiber reinforcement having a laminated structure such as in unidirectional (1-D) or bidirectional (2-D) fiber architecture (lay-ups of unidirectional plies or stacked fabric). This test method does not address composites with nonlaminated structures, such as (3-D) fiber architecture or discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics.
1.4 Values expressed in this test method are in accordance with the International System of Units (SI) and Practice E 380.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation:C1425–99
Standard Test Method for
Interlaminar Shear Strength of 1–D and 2–D Continuous
Fiber-Reinforced Advanced Ceramics at Elevated
Temperatures
This standard is issued under the fixed designation C 1425; 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 D 3878 Terminology of High-Modulus Reinforcing Fibers
and Their Composites
1.1 Thistestmethodaddressesthecompressionofadouble-
E4 Practices for Force Verification of Testing Machines
notched specimen to determine interlaminar shear strength of
E6 TerminologyelatingtoMethodsofMechanicalTesting
continuous fiber-reinforced ceramic composites (CFCCs) at
E 122 Practice for Choice of Sample Size to Estimate a
elevated temperatures. Specimen preparation methods and
Measure of Quality for a Lot Process
requirements, testing modes (load or displacement control),
E 220 Test Method for Calibration of Thermocouples by
testing rates (load rate or displacement rate), data collection,
Comparison Techniques
and reporting procedures are addressed.
E 230 Temperature-Electromotive Force (EMF) Tables for
1.2 This standard does not purport to address all of the
Standardized Thermocouples
safety concerns, if any, associated with its use. It is the
E 337 Test Method for Measuring Humidity with a Psy-
responsibility of the user of this standard to establish appro-
chrometer (the Measurement of Wet-Bulb and Dry-Bulb
priate safety and health practices and determine the applica-
Temperatures)
bility of regulatory limitations prior to use. Specific precau-
E 380 Practice for Use of International System of Units
tionary statements are noted in 8.1 and 8.2.
(SI)
1.3 This test method is used for testing advanced ceramic or
glass matrix composites with continuous fiber reinforcement
3. Terminology
having a laminated structure such as in unidirectional (1-D) or
3.1 Definitions—The definitions of terms relating to shear
bidirectional (2-D) fiber architecture (lay-ups of unidirectional
strength testing appearing in Terminology E6 apply to the
plies or stacked fabric). This test method does not address
terms used in this test method.The definitions of terms relating
composites with nonlaminated structures, such as (3-D) fiber
to advanced ceramics appearing in Terminology C 1145 apply
architecture or discontinuous fiber-reinforced, whisker-
to the terms used in this test method. The definitions of terms
reinforced, or particulate-reinforced ceramics.
relating to fiber-reinforced composites appearing in Terminol-
1.4 Values expressed in this test method are in accordance
ogy D 3878 apply to the terms used in this test method.
with the International System of Units (SI) and Practice E 380.
4. Summary of Test Method
2. Referenced Documents
4.1 This test method addresses the determination of the
2.1 ASTM Standards:
2 interlaminar shear strength of CFCCs at elevated temperatures.
C 1145 Terminology on Advanced Ceramics
The interlaminar shear strength of CFCCs, as determined by
C 1292 Test Method for Shear Strength of Continuous
2 this test method, is measured by loading in compression a
Fiber-Reinforced Ceramics at Ambient Temperatures
double-notched specimen of uniform width. Failure of the
D 695 Test Method for Compressive Properties of Rigid
specimen occurs by interlaminar shear between two centrally
Plastics
located notches machined halfway through the thickness of the
D 3846 Test Method for In-Plane Shear Strength of Rein-
specimen and spaced a fixed distance apart on opposing faces.
forced Plastics
Schematicsoftheloadingmodeandthespecimenareshownin
This test method is under the jurisdiction of ASTM Committee C-28 on
Advanced Ceramics and is the direct responsibility of Subcommittee C28.07 on Annual Book of ASTM Standards, Vol 15.03.
Ceramic Matrix Composites. Annual Book of ASTM Standards, Vol 03.01.
Current edition approved May 10, 1999. Published August 1999. Annual Book of ASTM Standards, Vol 14.02.
2 8
Annual Book of ASTM Standards, Vol 15.01. Annual Book of ASTM Standards, Vol 14.03.
3 9
Annual Book of ASTM Standards, Vol 08.01. Annual Book of ASTM Standards, Vol 11.03.
4 10
Annual Book of ASTM Standards, Vol 08.02. Annual Book of ASTM Standards, Vol 14.02.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
C1425–99
Fig. 1. The procedures in this test method are similar to those 5.4 This test method may be used for material development,
in Test Method C 1292 for the determination of the interlami- material comparison, quality assurance, characterization, and
nar shear strength of CFCCs at ambient temperature, except design data generation.
that the considerations for conducting the test at elevated 5.5 For quality control purposes, results derived from stan-
temperatures are addressed in this test method. dardized shear test specimens may be considered indicative of
the response of the material from which they were taken for
5. Significance and Use given primary processing conditions and post-processing heat
treatments.
5.1 Continuous fiber-reinforced ceramic composites are
candidate materials for structural applications requiring high
6. Interferences
degrees of wear and corrosion resistance, and damage toler-
6.1 Testenvironment(vacuum,inertgas,ambientair,andso
ance at high temperatures.
forth) including moisture content (for example, relative humid-
5.2 The 1-D and 2-D CFCCs are highly anisotropic and
ity) may have an influence on the measured interlaminar shear
their transthickness tensile and interlaminar shear strength are
strength. In particular, the behavior of materials susceptible to
lower than their in-plane tensile and in-plane shear strength,
slow crack growth fracture will be strongly influenced by test
respectively.
environment and testing rate.Testing to evaluate the maximum
5.3 Shear tests provide information on the strength and
strength potential of a material shall be conducted in inert
deformation of materials under shear stresses.
environmentsoratsufficientlyrapidtestingrates,orboth,soas
to minimize slow crack growth effects. Conversely, testing can
be conducted in environments and testing modes and rates
representative of service conditions to evaluate material per-
formance under those conditions.When testing is conducted in
uncontrolled ambient air with the objective of evaluating
maximumstrengthpotential,relativehumidityandtemperature
must be monitored and reported. Testing at humidity levels
>65 % RH is not recommended and any deviations from this
recommendation must be reported.
6.2 Preparation of test specimens, although normally not
considered a major concern with CFCCs, can introduce fabri-
cation flaws which may have pronounced effects on the
mechanical properties and behavior (for example, shape and
level of the resulting load-displacement curve and shear
strength). Machining damage introduced during specimen
preparation can be either a random interfering factor in the
determination of shear strength of pristine material, or an
inherent part of the strength characteristics to be measured.
Universal or standardized test methods of surface preparation
do not exist. Final machining steps may, or may not, negate
machining damage introduced during the initial machining.
Thus, specimen fabrication history may play an important role
in the measured strength distributions and shall be reported.
6.3 Bending in uniaxially loaded shear tests can cause or
promote nonuniform stress distributions that may alter the
desired state of stress during the test.
6.4 Fractures that initiate outside the gage section of a
specimen may be due to factors such as localized stress
concentrations, extraneous stresses introduced by improper
loading configurations, or strength-limiting features in the
microstructure of the specimen. Such non-gage section frac-
tures will normally constitute invalid tests.
6.5 For the evaluation of the interlaminar shear strength by
the compression of a double-notched specimen, the distance
between the notches has an effect on the maximum load and
11,12,13
therefore on the interlaminar shear strength . It has been
Whitney, J. M., “Stress Analysis of the Double Notch Shear Specimen,”
FIG. 1 Schematic of Compression of Double-Notched Specimen Proceedings of the American Society for Composites, 4th Technical Conference,
for the Determination of Interlaminar Shear Strength of CFCCs Blacksburg, VA, Technomic Publishing Co., Oct. 3-5, 1989, pp. 325.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
C1425–99
found that the stress distribution in the gage section of the meters, or electronic temperature controllers or readout units,
specimen is independent of the distance between the notches or combination thereof. Such measurements are subject to two
when the notches are far apart. However, when the distance types of error. Thermocouple calibration and instrument mea-
between the notches is such that the stress fields around the suring errors initially produce uncertainty as to the exact
notches interact, the measured interlaminar shear strength temperature. Secondly, both thermocouples and measuring
increases. Because of the complexity of the stress field around instruments may be subject to variations over time. Common
each notch and its dependence on the properties and homoge- errors encountered in the use of thermocouples to measure
neity of the material, conduct a series of tests on specimens temperatures include: calibration error, drift in calibration due
with different spacing between the notches to determine the to contamination or deterioration with use, lead-wire error,
effect of notch separation on the measured interlaminar shear errorarisingfrommethodofattachmenttothespecimen,direct
strength. radiation of heat to the bead, heat conduction along thermo-
6.6 For the evaluation of the interlaminar shear strength by couple wires, and so forth.
the compression of a double-notched specimen, excessive
7.3.2 Temperature measurements shall be made with ther-
clamping forces will reduce the stress concentration around the
mocouples of known calibration. Representative thermo-
notches and, therefore, artificially increase the measured inter-
couples shall be calibrated from each lot of wires used for
laminar shear strength. Excessive clamping might occur if
making noble-metal (for example, platinum or rhodium) ther-
interference between the fixture and the specimen results from
mocouples.Exceptforrelativelylowtemperaturesofexposure,
mismatch in their thermal expansion. Paragraph 7.6 provides
noble-metalthermocouplesareeventuallysubjecttoerrorupon
guidance to prevent this problem.
reuse. Oxidized noble-metal thermocouples shall not be reused
6.7 The interlaminar shear strength of 1-D and 2-D CFCCs
without clipping back to remove wire exposed to the hot zone,
is controlled either by the matrix-rich interlaminar regions or
re-welding, and annealing. Any reuse of noble-metal thermo-
by the weakest of the fiber-matrix interfaces. Whether
couples after relatively low-temperature use without this pre-
interlaminar-shear failure initiates at the matrix-rich interlami-
caution shall be accompanied by re-calibration data demon-
nar region or at the weakest of the fiber/matrix interfaces
strating that calibration was not unduly affected by the
depends on the location of the root of the notch, where the
conditions of exposure.
interlaminar shear stress is largest, with respect to the inter-
7.3.3 Measurement of the drift in calibration of thermo-
laminar microstructural features.
couples during use is difficult. When drift is a problem during
tests, a method shall be devised to check the readings of the
7. Apparatus
thermocouples monitoring the specimen temperature during
7.1 Testing Machines—The testing machine shall be in
the test. For reliable calibration of thermocouples after use, the
conformancewithPracticesE4.Theloadsusedindetermining
temperature gradient of the test furnace must be reproduced
shearstrengthshallbeaccuratewithin 61 %atanyloadwithin
during the re-calibration.
the selected load range of the testing machine as defined in
7.3.4 Temperature-measuring,controlling,andrecordingin-
PracticesE4.
struments shall be calibrated against a secondary standard,
7.2 Heating Apparatus—The apparatus for, and method of,
such as precision potentiometer, optical pyrometer, or black-
heating the specimens shall provide the temperature control
body thyristor. Lead-wire error shall be checked with the lead
necessary to satisfy the requirement of 10.2.
wires in place as they normally are used. For thermocouple
7.2.1 Heating can be by indirect electrical resistance (heat-
calibration procedures refer to Test Method E 220 and Tables
ingelements),indirectinductionthroughasusceptor,orradiant
E 230.
lamp with the specimen in ambient air at atmospheric pressure
7.4 Data Acquisition—At a minimum, autographic records
unless other environments are specifically applied and re-
of applied load and cross-head displacement versus time shall
ported. Note that direct resistance heating is not recommended
be obtained. Either analog chart recorders or digital data
for heating CFCCs due to possible differences of the electrical
acquisition systems may be used for this purpose although a
resistance of the constituent materials which may produce
digital record is recommended for ease of later data analysis.
nonuniform heating of the specimen.
Ideally, an analog chart recorder or plotter shall be used in
7.3 Temperature-Measuring Apparatus—The method of
conjunction with the digital data acquisition system to provide
temperature measurement shall be sufficiently sensitive and
an immediate record of the test as a supplement to the digital
reliabletoensurethatthetemperatureofthespecimeniswithin
record. Recording devices must be accurate to 61 % of full
the limits specified in 10.2.
scale and shall have a minimum data acquisition rate of 10 Hz
7.3.1 Primary temperature measurement shall be made with
with a response of 50 Hz deemed more than sufficient.
thermocouples in conjunction with potentiometers, millivolt-
7.5 Dimension-Measuring Devices—Micrometers and other
devices used for measuring linear dimensions mu
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