ASTM C1469-00
(Test Method)Standard Test Method for Shear Strength of Joints of Advanced Ceramics at Ambient Temperature
Standard Test Method for Shear Strength of Joints of Advanced Ceramics at Ambient Temperature
SCOPE
1.1 This test method covers the determination of shear strength of joints in advanced ceramics at ambient temperature. Test specimen geometries, test specimen fabrication methods, testing modes (that is, force or displacement control), testing rates (that is, force or displacement rate), data collection, and reporting procedures are addressed.
1.2 This test method is used to measure shear strength of ceramic joints in test specimens extracted from larger joined pieces by machining. Test specimens fabricated in this way are not expected to warp due to the relaxation of residual stresses but are expected to be much straighter and more uniform dimensionally than butt-jointed test specimens prepared by joining two halves, which are not recommended. In addition, this test method is intended for joints, which have either low or intermediate strengths with respect to the substrate material to be joined. Joints with high strengths should not be tested by this test method because of the high probability of invalid tests resulting from fractures initiating at the reaction points rather than in the joint. Determination of the shear strength of joints using this test method is appropriate particularly for advanced ceramic matrix composite materials but also may be useful for monolithic advanced ceramic materials.
1.3 Values expressed in this test method are in accordance with the International System of Units (SI) and Practice E380.
This test method does not purport to address the safety problems associated with its use. It is the responsibility of the user of this test method 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.
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Designation:C1469–00
Standard Test Method for
Shear Strength of Joints of Advanced Ceramics at Ambient
Temperature
This standard is issued under the fixed designation C 1469; 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 Ceramics at Elevated Temperatures
C 1341 Test Method for Flexural Properties of Continuous
1.1 This test method covers the determination of shear
Fiber-Reinforced Advanced Ceramic Composites
strengthofjointsinadvancedceramicsatambienttemperature.
D 3878 Terminology of High-Modulus Reinforcing Fibers
Test specimen geometries, test specimen fabrication methods,
and Their Composites
testing modes (that is, force or displacement control), testing
D 5379/D 5379M Test Method for Shear Properties of
rates (that is, force or displacement rate), data collection, and
Composite Materials by the V-Notched Beam Method
reporting procedures are addressed.
E 4 Practices for Force Verification of Testing Machines
1.2 This test method is used to measure shear strength of
E 6 Terminology Relating to Methods of Mechanical Test-
ceramic joints in test specimens extracted from larger joined
ing
pieces by machining. Test specimens fabricated in this way are
E 122 Practice for Choice of Sample Size to Estimate the
not expected to warp due to the relaxation of residual stresses
Average Quality of a Lot Process
but are expected to be much straighter and more uniform
E 337 Test Method for Measuring Humidity with Psy-
dimensionally than butt-jointed test specimens prepared by
chrometer (the Measurement of Wet-Bulb and Dry-Bulb
joining two halves, which are not recommended. In addition,
Temperatures)
this test method is intended for joints, which have either low or
E 380 Practice for Use of International System of Units
intermediate strengths with respect to the substrate material to
(SI)
be joined. Joints with high strengths should not be tested by
this test method because of the high probability of invalid tests
3. Terminology
resulting from fractures initiating at the reaction points rather
3.1 Definitions—The definitions of terms relating to shear
than in the joint. Determination of the shear strength of joints
strength testing appearing in Terminology E 6, to advanced
using this test method is appropriate particularly for advanced
ceramicsappearinginTerminologiesC 1145andD 3878apply
ceramic matrix composite materials but also may be useful for
to the terms used in this test method.Additional terms used in
monolithic advanced ceramic materials.
conjunction with this test method are defined as follows.
1.3 Values expressed in this test method are in accordance
3.1.1 advanced ceramic, n—a highly-engineered, high-
with the International System of Units (SI) and Practice E 380.
performance predominately nonmetallic, inorganic, ceramic
1.4 This test method does not purport to address the safety
material having specific functional attributes. (C 1145)
problems associated with its use. It is the responsibility of the
3.1.2 breaking force [F], n—the force at which fracture
user of this test method to establish appropriate safety and
occurs.
health practices and determine the applicability of regulatory
3.1.3 ceramic matrix composite, n—a material consisting of
limitations prior to use. Specific precautionary statements are
two or more materials (insoluble in one another), in which the
noted in 8.1 and 8.2.
major, continuous component (matrix component) is a ceramic
2. Referenced Documents while the secondary component(s) may be ceramic, glass-
ceramic, glass, metal, or organic in nature. These components
2.1 ASTM Standards:
are combined on macroscale to form a useful engineering
C 1145 Terminology of Advanced Ceramics
material possessing certain properties or behaviour not pos-
C 1161 Test Method for Flexural Strength of Advanced
sessed by the individual constituents. (C 1275)
Ceramics at Ambient Temperatures
C 1211 Test Method for Flexural Strength of Advanced
Annual Book of ASTM Standards, Vol 15.03.
1 4
This test method is under the jurisdiction of ASTM Committee C-28 on Annual Book of ASTM Standards, Vol 03.01.
Advanced Ceramics and is the direct responsibility of Subcommittee C-28. Annual Book of ASTM Standards, Vol 14.02.
Current edition approved May 10, 2000. Published September 2000. Annual Book of ASTM Standards, Vol 11.03.
2 7
Annual Book of ASTM Standards, Vol 15.01. 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.
C1469–00
3.1.4 joining, n—controlled formation of chemical, or me- specimens of the same cross-section and using a standard
chanical bond, or both, between similar or dissimilar materials. four-point flexural strength test, for example, Test Method
3.1.5 shear strength [F/L ], n—the maximum shear stress C 1161 for monolithic advanced ceramic base material and
which a material is capable of sustaining. Shear strength is Test Method C 1341 for composite advanced ceramic base
calculated from the shear fracture force and the shear stressed material. If the joint flexural strength is low (that is, <25 % of
area. the flexural strength of the base material), the recommended
test specimen geometry for shear strength testing of the joint is
4. Summary of Test Method
the uniform test specimen shown in Fig. 1a. If the joint flexural
4.1 This test method describes an asymmetrical four-point strength is moderate (that is, 25 to 50 % of the flexural strength
flexure test method to determine shear strengths of advanced of the base material), the recommended test specimen geom-
ceramic joints. Test specimens and test setup are shown etry for shear strength testing of the joint is the straight- or
schematicallyinFig.1andFig.2,respectively.Selectionofthe V-notched test specimen shown in Fig. 1b and Fig. 1c,
test specimen geometry depends on the bond strength of the respectively. If the joint flexural strength is high (>50 % of the
joint, which may be determined by preparing longer test flexural strength of the base material) this test method should
NOTE 1—The width of the joint, which varies between 0.05 and 0.20 mm, based on the joining method used, is smaller than that of the notch in b).
All dimensions are given in mm.
FIG. 1 Schematics of Test Specimen Geometries: a) Uniform, b) Straight-Notched and c) V-Notched
C1469–00
FIG. 2 Schematic of Test Fixture
not be used to measure shear strength of advanced ceramic
joints because very high contact stresses at the reaction points
willprovideahighprobabilityofinvalidtests(thatis,fractures
not at the joint).
4.2 The testing arrangement of this test method is asym-
metrical flexure, as illustrated by the force, shear and moment
diagramsinFig.3a,Fig.3b,andFig.3c,respectively.Notethat
the greatest shear exists over a region of 6 S/2 around the
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centerline of the joint (see Fig. 3b). In addition, while the
moment is zero at the centerline of the joint, the maximum
moments occur at the inner reaction points (see Fig. 3c). The
pointsofmaximummomentsarewherethegreatestprobability
of fracture of the base material may occur if the joint flexural
strength, and therefore, joint shear strength is too high.
5. Significance and Use
5.1 Advanced ceramics are candidate materials for struc-
tural applications requiring high degrees of wear and corrosion
resistance, often at elevated temperatures.
5.2 Joints are produced to enhance the performance and
applicability of materials. While the joints between similar
materials are generally made for manufacturing complex parts
and repairing components, those involving dissimilar materials
usually are produced to exploit the unique properties of each
constituent in the new component. Depending on the joining
process, the joint region may be the weakest part of the
FIG. 3 Idealized a) Force, b) Shear, and c) Moment Diagrams for
component. Since under mixed-mode and shear loading, the
Asymmetric Four-point Flexure, Where S and S Are the Outer
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loadtransferacrossthejointrequiresreasonableshearstrength,
and Inner Reaction Span Distances, Respectively, and P is the
it is important that the quality and integrity of joint under
Applied Force
in-plane shear forces be quantified. Shear strength data are also
needed to monitor the development of new and improved
joining techniques. 5.4 This test method may be used for material development,
5.3 Shear tests provide information on the strength and material comparison, quality assurance, characterization, and
deformation of materials under shear stresses. design data generation.
C1469–00
5.5 For quality control purposes, results derived from stan- reaction points. Depending on this relative strength, it may be
dardized shear test specimens may be considered indicative of necessary to conduct preliminary tests to establish the appro-
the response of the material from which they were taken for priate S and S distances for the fixture to be used.
o i
given primary processing conditions and post-processing heat 6.4 The accuracy of insertion and alignment of the test
treatments. specimen with respect to the fixture is critical; therefore,
preparations for testing should be done carefully to minimize
6. Interferences
thebendingmomentatthejoint,whichstronglydependsonthe
6.1 Fractures that initiate outside of the joint region may be
inner and outer reaction spans, as seen in Fig. 3c. See details in
due to factors, such as localized stress concentrations, extra- 10.4.
neous stresses introduced by improper force transfer. Such
6.5 Test environment (vacuum, inert gas, ambient air, etc.)
fractures will constitute invalid tests. including moisture content, for example, relative humidity,
6.2 Since the joint width is typically small, that is, 0.05 to
may have an influence on the measured shear strength. Con-
0.20 mm, the proper machining of the notches at the joint versely, testing can be conducted in environments and testing
region is very critical (see Fig. 1). Improper machining of the
modes and rates representative of service conditions to evalu-
notches can lead to undesired fracture at the reaction points. ate material performance under those conditions. When testing
Furthermore, nonsymmetrical machining of the nothces can be is conducted in uncontrolled ambient air with the objective of
decisive as to how the fracture occurs between the nothces. evaluating maximum strength potential, relative humidity and
temperature must be monitored and reported. Testing at hu-
NOTE 1—Finite element stress analysis of nonsymmetrical nothces
midity levels >65 % RH is not recommended and any devia-
showed that when there is a misalignment between the notches and the
tions from this recommendation shall be reported.
mid-plane of the joint, spurious normal (s ) tensile stresses are generated
x
at the notches which tend to “tear” the joint and would artificially affect
(reduce) the magnitude of shear strength measured from the joint. The 7. Apparatus
magnitude of these tensile stresses could be significant depending on the
7.1 Testing Machines—The testing machine shall be in
material system being investigated. Based on this analysis, it is recom-
conformance with Practice E 4.The forces used in determining
mended that the ratio of misalignment between the notch root and
shear strength shall be accurate within 61 % at any force
mid-plane of the joint, d, and the distance between the notches, h, should
within the selected force range of the testing machine as
be kept to less than 0.0125. (See Fig. 4.)
defined in Practice E 4.
6.3 In this test method, the shear force required to cause
7.2 Data Acquisition—At a minimum, autographic records
fracture in the joint region depends on the span lengths of S
o
of applied force and cross-head displacement versus time shall
and S inthefixture (seeFig.3).Theselengthsandthestrength
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be obtained. Either analog chart recorders or digital data
of the joint relative to that of the base material determine
acquisition systems may be used for this purpose although a
whether fracture takes place at the joint region or at the
digital record is recommended for ease of later data analysis.
Ideally, an analog chart recorder or plotter should be used in
8 conjunction with the digital data acquisition system to provide
J.M. Slepetz, T.F. Zagaeski, and R.F. Novello, “In-Plane Shear Test for
Composite Materials”, AMMRC-TR-78-30, Army Materials and Mechanics Re- an immediate record of the test as a supplement to the digital
search Center, Watertown, MA, July 1978.
record. Recording devices shall be accurate to 6 1 % of full
scale and shall have a minimum data acquisition rate of 10 Hz
with a response of 50 Hz deemed more than sufficient.
7.3 Dimension-Measuring Devices—Micrometers and other
devices used for measuring linear dimensions must be accurate
and precise to at least 0.01 mm.
7.4 Combination Square—Used to draw perpendicular lines
to specimen axis at the locations of inner loading points. The
tolerance must be within 0.5°.
7.5 Test Fixture—Thetestfixtureconsistsoftopandbottom
sections, reaction-pins, and a force transfer ball, as shown
schematically in Fig. 2. The bottom section is placed on a
stationary base, for example, a compression platen. The test
specimen is positioned between the top and bottom sections of
thefixture.Theforceistransmittedfromthetestmachinetothe
fixture by the force transfer ball; however, a pin also can be
used in place of the force transfer ball. Table 1 contains
symbols, nomenclature, and recommended dimensions for the
test fixture (Fig. 2), where the tolerances for S and S after
o i
NOTE 1—It is recommended that d/h ratio in both notch types is less
than 0.0125.
Ö. Ünal, I.E.Anderson, and S.I. Maghsoodi, “ATest Method to Measure Shear
FIG. 4 Schematic of Misalignment, d, between the Joint Line and Strength of Ceramic Joints at High Temperatures,” J. Am. Ceram. Soc., 80, 1281
Notch Root Shown for Straight—Notched Specimen (1997).
C1469–00
TABLE 1 Recommended Dimensions for Test Fixture TABLE 2 Recommended Dimensions for Test Specimens
Dimension Description Nominal Value Tolerance Dimension Description Nominal Value Tolerance
S Inner span 4.0 mm 6 0.2 mm L Test specimen length 36.0 mm 60.5
i
S Outer span 30.0 mm 6 0.2 mm H Test specimen height 4.0 mm 6 0.1
o
Force transfer ball 7.5 mm 6 0.1 mm B Test specime
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