1、Designation: C 1292 00 (Reapproved 2005)Standard Test Method forShear Strength of Continuous Fiber-Reinforced AdvancedCeramics at Ambient Temperatures1This standard is issued under the fixed designation C 1292; the number immediately following the designation indicates the year oforiginal adoption o
2、r, 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.1. Scope1.1 This test method covers the determination of shearstrength of continuous fibe
3、r-reinforced ceramic composites(CFCCs) at ambient temperature. The test methods addressedare (1) the compression of a double-notched specimen todetermine interlaminar shear strength and (2) the Iosipescu testmethod to determine the shear strength in any one of thematerial planes of laminated composi
4、tes. Specimen fabricationmethods, testing modes (load or displacement control), testingrates (load rate or displacement rate), data collection, andreporting procedures are addressed.1.2 This test method is used for testing advanced ceramic orglass matrix composites with continuous fiber reinforcemen
5、thaving uni-directional (1-D) or bi-directional (2-D) fiber archi-tecture. This test method does not address composites with(3-D) fiber architecture or discontinuous fiber-reinforced,whisker-reinforced, or particulate-reinforced ceramics.1.3 The values stated in SI units are to be regarded as thesta
6、ndard and are in accordance with IEEE/ASTM SI 10.1.4 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 of re
7、gulatory limitations prior to use. Specific hazardstatements are given in 8.1 and 8.2.2. Referenced Documents2.1 ASTM Standards:2C 1145 Terminology of Advanced CeramicsD 695 Test Method for Compressive Properties of RigidPlasticsD 3846 Test Method for In-Plane Shear Strength of Rein-forced PlasticsD
8、 3878 Terminology for Composite MaterialsD 5379/D 5379M Test Method for Shear Properties ofComposite Materials by the V-Notched Beam MethodE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 122 Practice for Calculating Sample Size to Est
9、imate,With a Specified Tolerable Error, the Average for Charac-teristic of a Lot or ProcessE 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)E 691 Practice for Cond
10、ucting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminology3.1 DefinitionsThe definitions of terms relating to shearstrength testing appearing in Terminolo
11、gy E6 apply to theterms used in this test method. The definitions of terms relatingto advanced ceramics appearing in Terminology C 1145 applyto the terms used in this test method. The definitions of termsrelating to fiber-reinforced composites appearing in Terminol-ogy D 3878 apply to the terms used
12、 in this test method.Additional terms used in conjunction with this test method aredefined in the following.3.1.1 advanced ceramicengineered high-performancepredominately nonmetallic, inorganic, ceramic material havingspecific functional attributes.3.1.2 continuous fiber-reinforced ceramic matrix co
13、mposite(CFCC)ceramic matrix composite in which the reinforcingphase consists of a continuous fiber, continuous yarn, or awoven fabric.3.1.3 shear failure loadmaximum load required to frac-ture a shear loaded test specimen.1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced C
14、eramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Composites.Current edition approved June 1, 2005. Published June 2005. Originallyapproved in 1995. Last previous edition approved in 2000 as C 1292 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org
15、, 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 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.4 shear st
16、rengthmaximum shear stress that a materialis capable of sustaining. Shear strength is calculated from theshear fracture load and the shear loaded area.4. Summary of Test Method4.1 This test method addresses two methods to determinethe shear strength of CFCCs: (1) the compression of adouble-notched s
17、pecimen test method to determine interlami-nar shear strength,3and (2) the Iosipescu test method todetermine the shear strength in any one of the material planesof laminated CFCCs.44.1.1 Shear Test by Compression Loading of Double-Notched SpecimensThe interlaminar shear strength ofCFCCs, as determin
18、ed by this method is measured by loadingin compression a double-notched specimen of uniform width.Failure of the specimen occurs by shear between two centrallylocated notches machined halfway through the thickness andspaced a fixed distance apart on opposing faces. Schematics ofthe test setup and th
19、e specimen are shown in Fig. 1 and Fig. 2.4.1.2 Shear Test By the Iosipescu MethodThe shearstrength of one of the different material shear planes oflaminated CFCCs may be determined by loading a coupon inthe form of a rectangular flat strip with symmetric centrallylocated V-notches using a mechanica
20、l testing machine and afour-point asymmetric fixture. The loading can be idealized asasymmetric flexure by the shear and bending diagrams in Fig.3. Failure of the specimen occurs by shear between theV-notches. Different specimen configurations are addressed forthis test method. Schematics of the tes
21、t setup and specimen areshown in Fig. 4 and Fig. 5. The determination of shearproperties of polymer matrix composites by the Iosipescumethod has been presented in Test Method D 5379/D 5379M.5. Significance and Use5.1 Continuous fiber-reinforced ceramic composites arecandidate materials for structura
22、l applications requiring highdegrees of wear and corrosion resistance, and damage toler-ance at high temperatures.5.2 Shear tests provide information on the strength anddeformation of materials under shear stresses.5.3 This test method may be used for material development,material comparison, qualit
23、y assurance, characterization, anddesign data generation.5.4 For quality control purposes, results derived from stan-dardized shear test specimens may be considered indicative ofthe response of the material from which they were taken forgiven primary processing conditions and post-processing heattre
24、atments.6. Interferences6.1 Test environment (vacuum, inert gas, ambient air, etc.)including moisture content (for example, relative humidity)may have an influence on the measured shear strength. Inparticular, the behavior of materials susceptible to slow crackgrowth fracture will be strongly influe
25、nced by test environmentand testing rate. Testing to evaluate the maximum strength3Whitney, J., M., “Stress Analysis of the Double Notch Shear Specimen,”Proceedings of the American Society for Composites, 4th Technical Conference,Blacksburg Virginia, Oct. 35, 1989, Technomic Publishing Co, pp. 325.4
26、Iosipescu, N., “New Accurate Procedure for Shear Testing of Metals,” Journalof Materials, 2, 3, Sept. 1967, pp. 537566.FIG. 1 Schematic of Test Fixture for the Double-NotchedCompression SpecimenNOTE 1All tolerances are in millimetres.FIG. 2 Schematic of Double-Notched Compression SpecimenC 1292 00 (
27、2005)2potential of a material shall be conducted in inert environmentsor at sufficiently rapid testing rates, or both, so as to minimizeslow crack growth effects. Conversely, testing can be con-ducted in environments and testing modes and rates represen-tative of service conditions to evaluate mater
28、ial performanceunder those conditions. When testing is conducted in uncon-trolled ambient air with the intent of evaluating maximumstrength potential, relative humidity and temperature must bemonitored and reported. Testing at humidity levels 65 % RHis not recommended and any deviations from this re
29、commen-dation must be reported.6.2 Preparation of test specimens, although normally notconsidered a major concern with CFCCs, can introduce fabri-cation flaws which may have pronounced effects on themechanical properties and behavior (for example, shape andlevel of the resulting load-displacement cu
30、rve and shearstrength). Machining damage introduced during specimenpreparation can be either a random interfering factor in thedetermination of shear strength of pristine material, or aninherent part of the strength characteristics to be measured.Universal or standardized test methods of surface pre
31、parationdo not exist. Final machining steps may, or may not negatemachining damage introduced during the initial machining.Thus, specimen fabrication history may play an important rolein the measured strength distributions and shall be reported.6.3 Bending in uniaxially loaded shear tests can cause
32、orpromote nonuniform stress distributions that may alter thedesired uniform state of stress during the test.6.4 Fractures that initiate outside the uniformly stressedgage section of a specimen may be due to factors such aslocalized stress concentrations, extraneous stresses introducedNOTE 1The loads
33、 are depicted as being concentrated, whereas theyare actually distributed over an area.FIG. 3 Idealized Force, Shear, and Moment Diagrams forAsymmetric Four-Point LoadingFIG. 4 Schematic of Test Fixture for the Iosipescu TestNOTE 1All tolerances are in millimetres.FIG. 5 Schematic of the Iosipescu S
34、pecimenC 1292 00 (2005)3by improper loading configurations, or strength-limiting fea-tures in the microstructure of the specimen. Such non-gagesection fractures will normally constitute invalid tests.6.5 For the conduction of the Iosipescu test, thin testspecimens (width to thickness ratio of more t
35、han ten) maysuffer from splitting and instabilities rendering in turn invalidtest results.6.6 For the evaluation of the interlaminar shear strength bythe compression of a double-notched specimen, the distancebetween the notches in the specimen has an effect on themaximum load and therefore on the sh
36、ear strength. It has beenfound that the stress distribution in the specimen is independentof the distance between the notches when the notches are farapart. However, when the distance between the notches is suchthat the stress fields around the notches interact, the measuredinterlaminar shear streng
37、th increases. Because of the complex-ity of the stress field around each notch and its dependence onthe properties and homogeneity of the material, it is recom-mended to conduct a series of tests on specimens with differentspacing between the notches to determine their effect on themeasured interlam
38、inar shear strength.6.7 For the evaluation of the interlaminar shear strength bythe compression of a double-notched specimen, excessiveclamping force with the jaws will reduce the stress concentra-tion around the notches and therefore artificially increase themeasured interlaminar shear strength. Be
39、cause the purpose ofthe jaws is to maintain the specimen in place and to preventbuckling, avoid overtightening the jaws.6.8 Most fixtures incorporate an alignment mechanism inthe form of a guide rod and a linear roller bearing. Excessivefree play or excessive friction in this mechanism may introduce
40、spurious moments that will alter the ideal loading conditions.7. Apparatus7.1 Testing MachinesThe testing machine shall be inconformance with Practices E4. The loads used in determiningshear strength shall be accurate within 61 % at any load withinthe selected load range of the testing machine as de
41、fined inPractices E4.7.2 Data AcquisitionAt the minimum, autographicrecords of applied load and cross-head displacement versustime shall be obtained. Either analog chart recorders or digitaldata acquisition systems may be used for this purpose althougha digital record is recommended for ease of late
42、r data analysis.Ideally, an analog chart recorder or plotter shall be used inconjunction with the digital data acquisition system to providean immediate record of the test as a supplement to the digitalrecord. Recording devices must be accurate to 61 % of fullscale and shall have a minimum data acqu
43、isition rate of 10 Hzwith a response of 50 Hz deemed more than sufficient.7.3 Dimension-Measuring DevicesMicrometers and otherdevices used for measuring linear dimensions must be accurateand precise to at least 0.01 mm.7.4 Test Fixtures:7.4.1 Double-notched Compression SpecimenThe fixtureconsists of
44、 a stationary element mounted on a base plate, anelement that attaches to the crosshead of the testing machine,and two jaws to fix the specimen in position. A schematicdescription of the test fixture is shown in Fig. 1.5A supportingjig conforming to the geometry of that shown in Fig. 1 of TestMethod
45、 D 3846 or Fig. 4 of Test Method D 695 may also beused.7.4.2 Iosipescu SpecimenThe fixture shall be a four-pointasymmetric flexure fixture shown schematically in Fig. 4.5Thisfixture consists of a stationary element mounted on a baseplate, and a movable element capable of vertical translationguided b
46、y a stiff post. The movable element attaches to thecross-head of the testing machine. Each element clamps half ofthe test specimen into position with a wedge action grip able tocompensate for minor specimen width variations. A span of 13mm is left unsupported between fixture halves. An alignmenttool
47、 is recommended to ensure that the specimen notch isaligned with the line-of-action of the loading fixture.8. Hazards8.1 During the conduct of this test method, the possibility offlying fragments of broken test material may be high. Thebrittle nature of advanced ceramics and the release of strainene
48、rgy contribute to the potential release of uncontrolledfragments upon fracture. Means for containment and retentionof these fragments for later fractographic reconstruction andanalysis is highly recommended.8.2 Exposed fibers at the edges of CFCC specimens presenta hazard due to the sharpness and br
49、ittleness of the ceramicfiber. All persons required to handle these materials shall bewell informed of these conditions and the proper handlingtechniques.9. Test Specimens9.1 Test Specimen Geometry:9.1.1 Double-Notched Compression SpecimenThe testspecimens shall conform to the shape and tolerances shown inFig. 2. The specimen consists of a rectangular plate withnotches machined on both sides. The depth of the notches shallbe at least equal to one half of the specimen thickness, and thedistance between the notches shall be determined consideringthe requirements to
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1