1、Designation: C1292 10Standard Test Method forShear Strength of Continuous Fiber-Reinforced AdvancedCeramics at Ambient Temperatures1This standard is issued under the fixed designation C1292; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, 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. Scope1.1 This test method covers the determination of shearstrength of continuous fiber-reinforced ceramic
3、composites(CFCCs) at ambient temperature. The test methods addressedare (1) the compression of a double-notched test specimen todetermine interlaminar shear strength and (2) the Iosipescu testmethod to determine the shear strength in any one of thematerial planes of laminated composites. Test specim
4、en fabri-cation methods, testing modes (load or displacement control),testing rates (load rate or displacement rate), data collection,and reporting procedures are addressed.1.2 This test method is used for testing advanced ceramic orglass matrix composites with continuous fiber reinforcementhaving u
5、ni-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 thestandard and
6、 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 regulatory
7、limitations prior to use. Specific hazardstatements are given in 8.1 and 8.2.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsD695 Test Method for Compressive Properties of RigidPlasticsD3846 Test Method for In-Plane Shear Strength of Rein-forced PlasticsD3878 Termino
8、logy for Composite MaterialsD5379/D5379M Test Method for Shear Properties of Com-posite Materials by the V-Notched Beam MethodE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Estimate,With Spec
9、ified Precision, the Average for a Characteristicof a Lot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E691 Practice for Conducting an Interlaborator
10、y 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 Terminology E6 apply to theterms
11、used in this test method. The definitions of terms relatingto advanced ceramics appearing in Terminology C1145 applyto the terms used in this test method. The definitions of termsrelating to fiber-reinforced composites appearing in Terminol-ogy D3878 apply to the terms used in this test method.Addit
12、ional 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 composite(CFCC)ceramic matri
13、x composite in which the reinforcingphase consists of a continuous fiber, continuous yarn, or awoven fabric.3.1.3 shear failure force (F)maximum force required tofracture a shear-loaded test specimen.1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the dir
14、ect responsibility of Subcommittee C28.07 onCeramic Matrix Composites.Current edition approved Dec. 1, 2010. Published January 2011. Originallyapproved in 1995. Last previous edition approved in 2005 as C1292 00 (2005).DOI: 10.1520/C1292-10.2For referenced ASTM standards, visit the ASTM website, www
15、.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 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.4
16、 shear strength (F/L2)maximum shear stress that amaterial is capable of sustaining. Shear strength is calculatedfrom breaking force in shear and shear area.4. Summary of Test Method4.1 This test method addresses two methods to determinethe shear strength of CFCCs: (1) the compression test methodto d
17、etermine interlaminar shear strength of a double-notchedtest specimen,3and (2) the Iosipescu test method to determinethe shear strength in any one of the material planes oflaminated CFCCs.44.1.1 Shear Test by Compression Loading of Double-Notched Test SpecimensThe interlaminar shear strength ofCFCCs
18、, as determined by this method is measured by loadingin compression a double-notched test specimen of uniformwidth. Failure of the test specimen occurs by shear betweentwo centrally located notches machined halfway through thethickness and spaced a fixed distance apart on opposing faces.Schematics o
19、f the test setup and the test specimen are shown inFig. 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 testspecimen in the form of a rectangular flat strip with symmetriccentrally l
20、ocated V-notches using a mechanical testing machineand a four-point asymmetric fixture. The loading can beidealized as asymmetric flexure by the shear and bendingdiagrams in Fig. 3. Failure of the test specimen occurs by shearbetween the V-notches. Different test specimen configurationsare addressed
21、 for this test method. Schematics of the test setupand test specimen are shown in Fig. 4 and Fig. 5. Thedetermination of shear properties of polymer matrix compos-ites by the Iosipescu method has been presented in Test MethodD5379/D5379M.5. Significance and Use5.1 Continuous fiber-reinforced ceramic
22、 composites arecandidate materials for structural 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
23、material development,material comparison, quality 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 p
24、rocessing conditions and post-processing heattreatments.6. Interferences6.1 Test environment (vacuum, inert gas, ambient air, etc.)including moisture content (for example, relative humidity)3Whitney, J., M., “Stress Analysis of the Double Notch Shear Specimen,”Proceedings of the American Society for
25、 Composites, 4th Technical Conference,Blacksburg Virginia, Oct. 35, 1989, Technomic Publishing Co, pp. 325.4Iosipescu, 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 Test S
26、pecimenNOTE 1All tolerances are in millimetres.FIG. 2 Schematic of Double-Notched Compression TestSpecimenC1292 102may have an influence on the measured shear strength. Inparticular, the behavior of materials susceptible to slow crackgrowth fracture will be strongly influenced by test environmentand
27、 testing rate. Testing to evaluate the maximum strengthpotential 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 repres
28、en-tative of service conditions to evaluate material 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 % RHi
29、s not recommended and any deviations from this recommen-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, sha
30、pe andlevel of the resulting load-displacement curve and shearstrength). Machining damage introduced during test 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
31、.Universal or standardized test methods of surface preparationdo not exist. Final machining steps may, or may not negatemachining damage introduced during the initial machining.Thus, test specimen fabrication history may play an importantrole in the measured strength distributions and shall bereport
32、ed.NOTE 1The loads 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
33、of the Iosipescu SpecimenC1292 1036.3 Bending in uniaxially loaded shear tests can cause 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 test specimen may be due to
34、 factors such aslocalized stress concentrations, extraneous stresses introducedby 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,
35、 thin testspecimens (width to thickness ratio of more than 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 test specimen, the dis-tance between the notches in the spe
36、cimen has an effect on themaximum load and therefore on the shear strength. It has beenfound that the stress distribution in the test specimen isindependent of the distance between the notches when thenotches are far apart. However, when the distance between thenotches is such that the stress fields
37、 around the notches interact,the measured interlaminar shear strength increases. Because ofthe complexity of the stress field around each notch and itsdependence on the properties and homogeneity of the material,it is recommended to conduct a series of tests on test specimenswith different spacing b
38、etween the notches to determine theireffect on the measured interlaminar shear strength.6.7 For the evaluation of the interlaminar shear strength bythe compression of a double-notched test specimen, excessiveclamping force with the jaws will reduce the stress concentra-tion around the notches and th
39、erefore artificially increase themeasured interlaminar shear strength. Because the purpose ofthe jaws is to maintain the specimen in place and to preventbuckling, avoid overtightening the jaws.6.8 Most test fixtures incorporate an alignment mechanismin the form of a guide rod and a linear roller bea
40、ring. Excessivefree play or excessive friction in this mechanism may introducespurious moments that will alter the ideal loading conditions.7. Apparatus7.1 Testing MachinesThe testing machine shall be inconformance with Practices E4. The forces used in determiningshear strength shall be accurate wit
41、hin 61 % at any forcewithin the selected force range of the testing machine asdefined in Practices E4.7.2 Data AcquisitionAt the minimum, autographicrecords of applied force and cross-head displacement versustime shall be obtained. Either analog chart recorders or digitaldata acquisition systems may
42、 be used for this purpose althougha digital record is recommended for ease of later 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. Recordin
43、g devices must be accurate to 61 % of fullscale and shall have a minimum data acquisition 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
44、.7.4 Test Fixtures:7.4.1 Double-notched Compression Test SpecimenThetest fixture consists of a stationary element mounted on a baseplate, an element that attaches to the crosshead of the testingmachine, and two jaws to fix the test specimen in position. Aschematic description of the test fixture is
45、shown in Fig. 1.5Asupporting jig conforming to the geometry of that shown inFig. 1 of Test Method D3846 or Fig. 4 of Test Method D695may also be used.7.4.2 Iosipescu Test SpecimenThe test fixture shall be afour-point asymmetric flexure fixture shown schematically inFig. 4.5This test fixture consists
46、 of a stationary elementmounted on a base plate, and a movable element capable ofvertical translation guided by a stiff post. The movable elementattaches to the cross-head of the testing machine. Each elementclamps half of the test specimen into position with a wedgeaction grip able to compensate fo
47、r minor width variations ofthe test specimen.Aspan of 13 mm is left unsupported betweentest fixture halves. An alignment tool is recommended toensure that the test specimen notch is aligned with theline-of-action of the loading fixture.8. Hazards8.1 During the conduct of this test method, the possib
48、ility offlying fragments of broken test material may be high. Thebrittle nature of advanced ceramics and the release of strainenergy contribute to the potential release of uncontrolledfragments upon fracture. Means for containment and retentionof these fragments for later fractographic reconstructio
49、n andanalysis is highly recommended.8.2 Exposed fibers at the edges of CFCC test specimenspresent a hazard due to the sharpness and brittleness of theceramic fiber. All persons required to handle these materialsshall be well informed of these conditions and the properhandling techniques.9. Test Specimens9.1 Test Specimen Geometry:9.1.1 Double-Notched Compression Test SpecimenThetest specimens shall conform to the shape and tolerances shownin Fig. 2. The specimen consists of a rectangular plate withnotches machined on both sides. The depth of the notches shallbe a
