1、Designation: C1323 10Standard Test Method forUltimate Strength of Advanced Ceramics with DiametrallyCompressed C-Ring Specimens at Ambient Temperature1This standard is issued under the fixed designation C1323; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of ultimatestrength under monotonic
3、loading of advanced ceramics intubular form at ambient temperatures. The ultimate strength asused in this test method refers to the strength obtained undermonotonic compressive loading of C-ring specimens such asshown in Fig. 1 where monotonic refers to a continuousnonstop test rate with no reversal
4、s from test initiation to finalfracture. This method permits a range of sizes and shapes sincetest specimens may be prepared from a variety of tubularstructures. The method may be used with microminiature testspecimens.1.2 The values stated in SI units are to be regarded asstandard. No other units o
5、f measurement are included in thisstandard.1.2.1 Values expressed in this test method are in accordancewith the International System of Units (SI) and IEEE/ASTM SI10.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t
6、he user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1161 Test Method for Flexural Strength of AdvancedCeramics at Ambie
7、nt TemperatureC1239 Practice for Reporting Uniaxial Strength Data andEstimating Weibull Distribution Parameters for AdvancedCeramicsC1322 Practice for Fractography and Characterization ofFracture Origins in Advanced CeramicsC1368 Test Method for Determination of Slow CrackGrowth Parameters of Advanc
8、ed Ceramics by ConstantStress-Rate Flexural Testing at Ambient TemperatureC1683 Practice for Size Scaling of Tensile Strengths UsingWeibull Statistics for Advanced CeramicsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE337 Test Method
9、for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)IEEE/ASTM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminology3.1 Definitions:3.1.1 advanced ceramican engineered, high-performance,pred
10、ominately nonmetallic, inorganic, ceramic material havingspecific functional qualities. (C1145)3.1.2 breaking loadthe load at which fracture occurs.(E6)3.1.3 C-ringcircular test specimen geometry with themid-section (slot) removed to allow bending displacement(compression or tension). (E6)3.1.4 flex
11、ural strengtha measure of the ultimate strengthof a specified beam in bending.3.1.5 modulus of elasticitythe ratio of stress to corre-sponding strain below the proportional limit. (E6)3.1.6 slow crack growthsubcritical crack growth (exten-sion) which may result from, but is not restricted to, suchme
12、chanisms as environmentally assisted stress corrosion ordiffusive crack growth.4. Significance and Use4.1 This test method may be used for material development,material comparison, quality assurance, and characterization.Extreme care should be exercised when generating design data.4.2 For a C-ring u
13、nder diametral compression, the maxi-mum tensile stress occurs at the outer surface. Hence, theC-ring specimen loaded in compression will predominately1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.04 onAppli
14、cations.Current edition approved Jan. 1, 2010. Published March 2010. Originallyapproved in 1996. Last previous edition approved in 2007 as C1323 96(2001)e1.DOI: 10.1520/C1323-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
15、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*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.ev
16、aluate the strength distribution and flaw population(s) on theexternal surface of a tubular component. Accordingly, thecondition of the inner surface may be of lesser consequence inspecimen preparation and testing.NOTE 1A C-ring in tension or an O-ring in compression may be usedto evaluate the inter
17、nal surface.4.2.1 The flexure stress is computed based on simplecurved-beam theory (1, 2, 3, 4, 5).3It is assumed that thematerial is isotropic and homogeneous, the moduli of elasticityare identical in compression or tension, and the material islinearly elastic. These homogeneity and isotropy assump
18、tionspreclude the use of this standard for continuous fiber reinforcedcomposites.Average grain size(s) should be no greater than onefiftieth (150) of the C-ring thickness. The simple curved-beamtheory stress solution is in good agreement (typically betterthan 1%) with a theory of elasticity solution
19、 as discussed in (3)for the geometries chosen for this standard. The simple beamtheory stress equations are relatively simple. They are rela-tively easy to integrate for Weibull effective volume oreffective area computations as shown in Appendix X1.4.2.2 The simple curved beam and theory of elastici
20、ty stresssolutions both are two-dimensional plane stress solutions. Theydo not account for stresses in the axial (parallel to b) direction,or variations in the circumferential (hoop, su) stresses throughthe width (b) of the test piece. The variations in the circum-ferential stresses increase with in
21、creases in width (b) and ringthickness (t). The variations can be substantial ( 10 %) for testspecimens with large b.The circumferential stresses peak at theouter edges. Therefore, the width (b) and thickness (t)ofthespecimens permitted in this test method are limited so that axialstresses are negli
22、gible (see Ref. 5) and the variations of thecircumferential stresses from the nominal simple curved beamtheory stress calculations are typically less than 4 %. See Ref.(3) and (4) for more information on the variation of thecircumferential stresses as a function of ring thickness (t) andring width (
23、b).4.2.3 The test piece outer rim corners are vulnerable to edgedamage, another reason to minimize the differences in thecircumferential stresses across the ring outer surface.4.2.4 Other geometry Cring test specimens may be tested,but comprehensive finite element analyses shall be performedto obtai
24、n accurate stress distributions. If strengths are to bescaled (converted) to strengths of other sizes or geometries,then Weibull effective volumes or areas shall be computedusing the results of the finite element analyses.4.3 Because advanced ceramics exhibiting brittle behaviorgenerally fracture ca
25、tastrophically from a single dominant flawfor a particular tensile stress field, the surface area and volumeof material subjected to tensile stresses is a significant factor indetermining the ultimate strength. Moreover, because of thestatistical distribution of the flaw population(s) in advancedcer
26、amics exhibiting brittle behavior, a sufficient number ofspecimens at each testing condition is required for statisticalanalysis and design. This test method provides guidelines forthe number of specimens that should be tested for thesepurposes (see 8.4).3The boldface numbers in parentheses refer to
27、 a list of references at the end ofthis test method.FIG. 1 C-Ring Test Geometry with Defining Geometry and Reference Angle (u) for the Point of Fracture Initiation on the CircumferenceC1323 1024.4 Because of a multitude of factors related to materialsprocessing and component fabrication, the results
28、 of C-ringtests from a particular material or selected portions of a part, orboth, may not necessarily represent the strength and deforma-tion properties of the full-size end product or its in-servicebehavior.4.5 The ultimate strength of a ceramic material may beinfluenced by slow crack growth or st
29、ress corrosion, or both,and is therefore, sensitive to the testing mode, testing rate, orenvironmental influences, or a combination thereof. Testing atsufficiently rapid rates as outlined in this test method mayminimize the consequences of subcritical (slow) crack growthor stress corrosion.4.6 The f
30、lexural behavior and strength of an advancedmonolithic ceramic are dependent on the materials inherentresistance to fracture, the presence of flaws, or damageaccumulation processes, or a combination thereof. Analysis offracture surfaces and fractography, though beyond the scope ofthis test method, i
31、s highly recommended (further guidance maybe obtained from Practice C1322 and Ref (6).5. Interferences5.1 Test environment (vacuum, inert gas, ambient air, etc.)including moisture content (that is, relative humidity) mayhave an influence on the measured ultimate strength. Inparticular, the behavior
32、of materials susceptible to slow crack-growth fracture will be strongly influenced by test environmentand testing rate.Testing to evaluate the maximum inert strength(strength potential) of a material shall therefore be conductedin inert environments or at sufficiently rapid testing rates, orboth, so
33、 as to minimize slow crack-growth effects. Conversely,testing can be conducted in environments and testing modesand rates representative of service conditions to evaluatematerial performance under use conditions. When testing inuncontrolled ambient air for the purpose of evaluating maxi-mum inert st
34、rength (strength potential), relative humidity andtemperature must be monitored and reported. Testing at hu-midity levels 65 % RH is not recommended and any devia-tions from this recommendation must be reported.5.2 C-ring specimens are useful for the determination ofultimate strength of tubular comp
35、onents in the as-received/as-used condition without surface preparations that may distortthe strength controlling flaw population(s). Nonetheless, ma-chining damage introduced during specimen preparation can beeither a random interfering factor in the determination of themaximum inert strength (stre
36、ngth potential), or an inherent partof the strength characteristics being measured. Universal orstandardized methods of surface/sample preparation do notexist. Hence, final machining steps may or may not negatemachining damage introduced during the initial machining.Thus, specimen fabrication histor
37、y may play an important rolein the measured strength distributions and shall be reported.5.3 Very small C-ring test specimens made by micro fabri-cation methods may also be tested. These typically are tested inthe as-fabricated state and do not require any machiningpreparation. Chamfers or edge beve
38、ls may not be necessary.Dimensional nonuniformities (e.g., through-thickness tapers orfabrication template artifacts) may alter the stress state andcreate experimental errors.6. Apparatus6.1 LoadingSpecimens shall be loaded in any suitabletesting machine provided that uniform rates of direct loading
39、can be maintained. The system used to monitor the loadingshall be free from any initial lags and will have the capacity torecord the maximum load applied to the C-ring specimenduring the test. Testing machine accuracy shall be within 1.0 %in accordance with Practices E4.6.1.1 This test method permit
40、s the use of either fixedloading rams or, when necessary (see 9.3), a self-adjustingfixture.Aself-adjusting fixture may include a universal joint orspherically seated platen used in conjunction with the upperloading ram. Such an articulating fixture may be necessary toensure even line loading from f
41、ront to back across the top of aC-ring test specimen. Articulation from side to side is notrequired since a flat loading platen contacts the C-ring at its topon its centerline. When fixed loading rams are used, they shallbe aligned so that the platen surfaces which come into contactwith the specimen
42、s are parallel to within 0.015 mm over thewidth of the test piece.Alignment of the testing system must beverified at a minimum at the beginning and at the end of a testseries.An additional verification of alignment is recommended,although not required, at the middle of the test series.NOTE 2Atest se
43、ries is interpreted to mean a discrete group of tests onindividual specimens conducted within a discrete period of time on aparticular material configuration, test specimen geometry, test conditions,or other uniquely definable qualifier. For example, a test series may becomposed of one material comp
44、rising ten specimens of one geometrytested at a fixed rate in strain control to final fracture in ambient air).6.1.2 Materials such as foil or thin rubber sheet shall be usedbetween the loading rams and the specimen for ambienttemperature tests to reduce the effects of friction and toredistribute th
45、e load. Aluminum oxide (alumina) felt or otherhigh-temperature “cloth” with a high-temperature capabilitymay also be used at ambient or elevated temperature. The useof a material with a high-temperature capability is recom-mended to ensure consistency with elevated temperature tests(if planned), pro
46、vided the high-temperature “cloth” is chemi-cally compatible with the specimen at all testing temperatures.6.2 The fixture used during the tests shall be stiffer than thespecimen to ensure that a majority of the crosshead travel (atleast 80 %) is imposed on the C-ring specimen.6.3 Data AcquisitionAt
47、 the minimum, an autographicrecord of applied load shall be obtained. Either analog chartrecorders or digital data acquisition systems can be used forthis purpose. Ideally, an analog chart recorder or plotter shallbe used in conjunction with a digital data acquisition system toprovide an immediate r
48、ecord of the test as a supplement to thedigital record. Recording devices shall be accurate to 0.1 % offull scale and shall have a minimum data acquisition rate of 10Hz with a response of 50 Hz deemed more than sufficient.7. Hazards7.1 During the conduct of this test, the possibility of flyingfragme
49、nts of broken test material may be high. Means forcontainment and retention of these fragments for safety, laterfractographic reconstruction, and analysis is highly recom-mended. It is advisable to buffer the fragments so that they doC1323 103not suffer needless secondary impact fractures. Tape applied tothe inside diameter may aid in specimen fragment retention.8. Specimen8.1 GeneralThe C-ring geometry is designed to evaluatethe ultimate strength of advanced monolithic materials intubular form in as-received or as-machined form. Whenpossible, the specimen shall ref
