1、Designation: C 1275 00 (Reapproved 2005)e1Standard Test Method forMonotonic Tensile Behavior of Continuous Fiber-ReinforcedAdvanced Ceramics with Solid Rectangular Cross-SectionTest Specimens at Ambient Temperature1This standard is issued under the fixed designation C 1275; the number immediately fo
2、llowing the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEThe Warning note in
3、 8.2.5.2 was editorially updated in June 2005.1. Scope1.1 This test method covers the determination of tensilebehavior including tensile strength and stress-strain responseunder monotonic uniaxial loading of continuous fiber-reinforced advanced ceramics at ambient temperature. This testmethod addres
4、ses, but is not restricted to, various suggestedtest specimen geometries as listed in the appendix. In addition,specimen fabrication methods, testing modes (force, displace-ment, or strain control), testing rates (force rate, stress rate,displacement rate, or strain rate), allowable bending, and dat
5、acollection and reporting procedures are addressed. Note thattensile strength as used in this test method refers to the tensilestrength obtained under monotonic uniaxial loading wheremonotonic refers to a continuous nonstop test rate with noreversals from test initiation to final fracture.1.2 This t
6、est method applies primarily to all advancedceramic matrix composites with continuous fiber reinforce-ment: uni-directional (1-D), bi-directional (2-D), and tri-directional (3-D). In addition, this test method may also beused with glass (amorphous) matrix composites with 1-D, 2-D,and 3-D continuous
7、fiber reinforcement. This test method doesnot address directly discontinuous fiber-reinforced, whisker-reinforced or particulate-reinforced ceramics, although the testmethods detailed here may be equally applicable to thesecomposites.1.3 Values expressed in this test method are in accordancewith the
8、 International System of Units (SI) and IEEE/ASTM SI10.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility
9、 of regulatory limitations prior to use. Specific hazardstatements are given in Section 7 and 8.2.5.2.2. Referenced Documents2.1 ASTM Standards:2C 1145 Terminology of Advanced CeramicsC 1239 Practice for Reporting Uniaxial Strength Data andEstimating Weibull Distribution Parameters for AdvancedCeram
10、icsD 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite MaterialsD 3379 Test Method for Tensile Strength and YoungsModulus for High-Modulus Single-Filament MaterialsD 3878 Terminology for Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology
11、 Relating to Methods of Mechanical Test-ingE83 Practice for Verification and Classification of Exten-someter SystemE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 337 Test Method for Measuring Humidity with Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures
12、)E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1012 Practice for Verification of Specimen AlignmentUnder Tensile LoadingIEEE/ASTM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminol
13、ogy3.1 DefinitionsThe definitions of terms relating to tensiletesting appearing in Terminology E6apply to the terms used inthis test method. The definitions of terms relating to advancedceramics appearing in Terminology C 1145 apply to the termsused in this test method. The definitions of terms rela
14、ting to1This practice is under the jurisdiction of ASTM Committee C28 on AdvancedCeramics and is the direct responsibility of Subcommittee C28.07 on CeramicMatrix Composites.Current edition approved June 1, 2005. Published June 2005. Originallyapproved in 1994. Last previous edition approved in 2000
15、 as C 1275 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor
16、Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.fiber reinforced composites appearing in Terminology D 3878apply to the terms used in this test method. Pertinent definitionsas listed in Practice E 1012, Terminology C 1145, TerminologyD 3878, and Terminology E6are shown in the fol
17、lowing withthe appropriate source given in parentheses. Additional termsused in conjunction with this test method are defined in thefollowing:3.1.1 advanced ceramic, nhighly engineered, high perfor-mance predominantly nonmetallic, inorganic, ceramic materialhaving specific functional attributes. C 1
18、1453.1.2 axial strainaverage longitudinal strains measured atthe surface on opposite sides of the longitudinal axis ofsymmetry of the specimen by two strain-sensing deviceslocated at the mid length of the reduced section. E 10123.1.3 bending straindifference between the strain at thesurface and the
19、axial strain. In general, the bending strainvaries from point to point around and along the reduced sectionof the specimen. E 10123.1.4 breaking forceforce at which fracture occurs. E63.1.5 ceramic matrix compositematerial consisting of twoor more materials (insoluble in one another), in which thema
20、jor, continuous component (matrix component) is a ceramic,while the secondary component/s (reinforcing component) maybe ceramic, glass-ceramic, glass, metal or organic in nature.These components are combined on a macroscale to form auseful engineering material possessing certain properties orbehavio
21、r not possessed by the individual constituents.3.1.6 continuous fiber-reinforced ceramic matrix composite(CFCC)ceramic matrix composite in which the reinforcingphase consists of a continuous fiber, continuous yarn, or awoven fabric.3.1.7 gage lengthoriginal length of that portion of thespecimen over
22、 which strain or change of length is determined.E63.1.8 matrix-cracking stressapplied tensile stress atwhich the matrix cracks into a series of roughly parallel blocksnormal to the tensile stress.3.1.9 DiscussionIn some cases, the matrix cracking stressmay be indicated on the stress-strain curve by
23、deviation fromlinearity (proportional limit) or incremental drops in the stresswith increasing strain. In other cases, especially with materialswhich do not possess a linear portion of the stress-strain curve,the matrix cracking stress may be indicated as the first stress atwhich a permanent offset
24、strain is detected in the unloadingstress-strain (elastic limit).3.1.10 modulus of elasticityratio of stress to correspond-ing strain below the proportional limit. E63.1.11 modulus of resiliencestrain energy per unit vol-ume required to elastically stress the material from zero to theproportional li
25、mit indicating the ability of the material toabsorb energy when deformed elastically and return it whenunloaded.3.1.12 modulus of toughnessstrain energy per unit volumerequired to stress the material from zero to final fractureindicating the ability of the material to absorb energy beyondthe elastic
26、 range (that is, damage tolerance of the material).3.1.13 Discussion The modulus of toughness can also bereferred to as the cumulative damage energy and as such isregarded as an indication of the ability of the material to sustaindamage rather than as a material property. Fracture mechanicsmethods f
27、or the characterization of CFCCs have not beendeveloped. The determination of the modulus of toughness asprovided in this test method for the characterization of thecumulative damage process in CFCCs may become obsoletewhen fracture mechanics methods for CFCCs become avail-able.3.1.14 proportional l
28、imit stressgreatest stress that a ma-terial is capable of sustaining without any deviation fromproportionality of stress to strain (Hookes law).3.1.15 DiscussionMany experiments have shown thatvalues observed for the proportional limit vary greatly with thesensitivity and accuracy of the testing equ
29、ipment, eccentricityof loading, the scale to which the stress-strain diagram isplotted, and other factors. When determination of proportionallimit is required, the procedure and sensitivity of the testequipment should be specified. (See Terminology E6.)3.1.16 percent bendingbending strain times 100
30、dividedby the axial strain. E 10123.1.17 slow crack growthsubcritical crack growth (exten-sion) which may result from, but is not restricted to, suchmechanisms as environmentally-assisted stress corrosion ordiffusive crack growth.3.1.18 tensile strengthmaximum tensile stress which amaterial is capab
31、le of sustaining. Tensile strength is calculatedfrom the maximum load during a tension test carried to ruptureand the original cross-sectional area of the specimen. E64. Significance and Use4.1 This test method may be used for material development,material comparison, quality assurance, characteriza
32、tion, anddesign data generation.4.2 Continuous fiber-reinforced ceramic matrix compositesgenerally characterized by fine grain sized (65 % relative humidity (RH) is not recommended and anydeviations from this recommendation must be reported.5.2 Surface preparation of test specimens, although nor-mal
33、ly not considered a major concern in CFCCs, can introducefabrication flaws that may have pronounced effects on tensilemechanical properties and behavior (for example, shape andlevel of the resulting stress-strain curve, tensile strength andstrain, proportional limit stress and strain, etc.). Machini
34、ngdamage introduced during specimen preparation can be eithera random interfering factor in the determination of ultimatestrength of pristine material (that is, increased frequency ofsurface initiated fractures compared to volume initiated frac-tures), or an inherent part of the strength characteris
35、tics to bemeasured. Surface preparation can also lead to the introductionof residual stresses. Universal or standardized test methods ofsurface preparation do not exist. It should be understood thatfinal machining steps may, or may not negate machiningdamage introduced during the initial machining.
36、Thus, speci-men fabrication history may play an important role in themeasured strength distributions and should be reported. Inaddition, the nature of fabrication used for certain composites(for example, chemical vapor infiltration or hot pressing) mayrequire the testing of test specimens in the as-
37、processedcondition (that is, it may not be possible to machine thespecimen faces).5.3 Bending in uniaxial tensile tests can cause or promotenon-uniform stress distributions with maximum stresses occur-ring at the specimen surface leading to non-representativefractures originating at surfaces or near
38、 geometrical transitions.In addition, if deformations or strains are measured at surfaceswhere maximum or minimum stresses occur, bending mayintroduce over or under measurement of strains depending onthe location of the strain-measuring device on the specimen.Similarly, fracture from surface flaws m
39、ay be accentuated orsuppressed by the presence of the non-uniform stresses causedby bending.5.4 Fractures that initiate outside the uniformly-stressedgage section of a test specimen may be due to factors such asstress concentrations or geometrical transitions, extraneousstresses introduced by grippi
40、ng, or strength-limiting features inthe microstructure of the specimen. Such non-gage sectionfractures will normally constitute invalid tests. In addition, forface-loaded geometries, gripping pressure is a key variable inthe initiation of fracture. Insufficient pressure can shear theouter plies in l
41、aminated CFCCs; while too much pressure cancause local crushing of the CFCC and fracture in the vicinity ofthe grips.6. Apparatus6.1 Testing MachinesMachines used for tensile testingshall conform to the requirements of Practice E4. The forceused in determining tensile strength shall be accurate with
42、in61 % at any force within the selected force range of the testingmachine as defined in Practice E4. A schematic showingpertinent features of the tensile testing apparatus is shown inFig. 1.6.2 Gripping Devices:6.2.1 GeneralVarious types of gripping devices may beused to transmit the measured load a
43、pplied by the testingmachine to the test specimens. The brittle nature of thematrices of CFCCs requires a uniform interface between thegrip components and the gripped section of the specimen. Lineor point contacts and non-uniform pressure can produceHertizan-type stresses leading to crack initiation
44、 and fracture ofthe test specimen in the gripped section. Gripping devices canC 1275 00 (2005)e13be classed generally as those employing active and thoseemploying passive grip interfaces as discussed in the followingsections.6.2.2 Active Grip InterfacesActive grip interfaces requirea continuous appl
45、ication of a mechanical, hydraulic, or pneu-matic force to transmit the load applied by the test machine tothe test specimen. Generally, these types of grip interfacescause a force to be applied normal to the surface of the grippedsection of the specimen. Transmission of the uniaxial forceapplied by
46、 the test machine is then accomplished by frictionbetween the test specimen and the grip faces. Thus, importantaspects of active grip interfaces are uniform contact betweenthe gripped section of the test specimen and the grip faces andconstant coefficient of friction over the grip/specimen inter-fac
47、e.6.2.2.1 For flat test specimens, face-loaded grips, either bydirect lateral pressure grip faces (1)3or by indirect wedge-typegrip faces, act as the grip interface (2) as illustrated in Fig. 2and Fig. 3, respectively. Generally, close tolerances are re-quired for the flatness and parallelism as wel
48、l as for the wedgeangle of the wedge grip faces. In addition, the thickness,flatness, and parallelism of the gripped section of the specimenmust be within similarly close tolerances to promote uniformcontact at the test specimen/grip interface. Tolerances will varydepending on the exact configuratio
49、n as shown in the appro-priate test specimen drawings.6.2.2.2 Sufficient lateral pressure must be applied to preventslippage between the grip face and the specimen. Grip surfacesthat are scored or serrated with a pattern similar to that of asingle-cut file have been found satisfactory. A fine serrationappears to be the most satisfactory. The serrations should bekept clean and well defined but not overly sharp. The lengthand width of the grip faces should be equal to or greater thanthe respective length and width of the gripped sections of thetest specimen.6.2
