1、Designation: C1425 19Standard Test Method forInterlaminar Shear Strength of 1D and 2D Continuous Fiber-Reinforced Advanced Ceramics at Elevated Temperatures1This standard is issued under the fixed designation C1425; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, 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 addresses the uniaxial compression ofa double-notched t
3、est specimen to determine interlaminar shearstrength of continuous fiber-reinforced ceramic composites(CFCCs) at elevated temperatures. Failure of the test specimenoccurs by interlaminar shear between two centrally locatednotches machined halfway through the thickness of the testspecimen and spaced
4、a fixed distance apart on opposing faces(see Fig. 1). Test specimen preparation methods andrequirements, testing modes (force or displacement control),testing rates (force rate or displacement rate), data collection,and reporting procedures are addressed.1.2 This test method is used for testing adva
5、nced ceramic orglass matrix composites with continuous fiber reinforcementhaving a laminated structure such as in unidirectional (1D) orbidirectional (2D) fiber architecture (lay-ups of unidirectionalplies or stacked fabric). This test method does not addresscomposites with nonlaminated structures,
6、such as (3D) fiberarchitecture or discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics.1.3 Values expressed in this test method are in accordancewith the International System of Units (SI) and IEEE/ASTMSI 10.1.4 This standard does not purport to address all of thesa
7、fety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are noted in 8.1 and 8.
8、2.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers
9、to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1292 Test Method for Shear Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient TemperaturesD695 Test Method for Compressive Properties of RigidPlasticsD3846 Test Method for In-
10、Plane Shear Strength of Rein-forced PlasticsD3878 Terminology for Composite MaterialsD6856/D6856M Guide for Testing Fabric-Reinforced “Tex-tile” Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calcula
11、ting Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE230/E230M Specification for Temperature-ElectromotiveForce (emf) Tables for Standardized ThermocouplesE337 Test Method f
12、or Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)IEEE/ASTM SI 10 American National Standard for MetricPractice3. Terminology3.1 DefinitionsThe definitions of terms relating to shearstrength testing appearing in Terminology E6 apply to theterms used in th
13、is 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.3.2 Definitions
14、 of Terms Specific to This Standard:3.2.1 shear failure force F, nmaximum force required tofracture a shear-loaded test specimen. C12921This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Compos
15、ites.Current edition approved Feb. 1, 2019. Published February 2019. Originallyapproved in 1999. Last previous edition approved in 2013 as C1425 13. DOI:10.1520/C1425-19.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
16、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis internat
17、ional standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Commit
18、tee.13.2.2 shear strength FL2, nmaximum shear stress that amaterial is capable of sustaining. Shear strength is calculatedfrom the failure force in shear and the shear area. C12924. Summary of Test Method4.1 This test method addresses the determination of theinterlaminar shear strength of CFCCs at e
19、levated temperatures.The interlaminar shear strength of CFCCs, as determined bythis test method, is measured by loading in uniaxial compres-sion a double-notched test specimen of uniform width. Failureof the test specimen occurs by interlaminar shear between twocentrally located notches machined hal
20、fway through the thick-ness of the test specimen and spaced a fixed distance apart onopposing faces. Schematics of the loading mode and the testspecimen are shown in Fig. 1. The procedures in this testmethod are similar to those in Test Method C1292 for thedetermination of the interlaminar shear str
21、ength of CFCCs atambient temperature, except that the considerations for con-ducting the test at elevated temperatures are addressed in thistest method.5. Significance and Use5.1 Continuous fiber-reinforced ceramic composites arecandidate materials for structural applications requiring highdegrees o
22、f wear, erosion, corrosion resistance, and damagetolerance at high temperatures.5.2 The 1D and 2D CFCCs are highly anisotropic and theirtransthickness tensile and interlaminar shear strength are lowerthan their in-plane tensile and in-plane shear strength, respec-tively.5.3 Shear tests provide infor
23、mation on the strength anddeformation of materials under shear stresses.5.4 This test method may be used for material development,material comparison, quality assurance, characterization, anddesign data generation.5.5 For quality control purposes, results derived from stan-dardized shear test specim
24、ens may be considered indicative ofthe response of the material from which they were taken forgiven primary processing conditions and post-processing heattreatments.6. Interferences6.1 Test environment (vacuum, inert gas, ambient air, and soforth), including moisture content (for example, relativehu
25、midity), may have an influence on the measured interlaminarshear strength. In particular, the behavior of materials suscep-tible to slow crack growth will be strongly influenced by testenvironment and testing rate. Testing to evaluate the maximumstrength potential of a material shall be conducted in
26、 inertenvironments or at sufficiently rapid testing rates, or both, so asto minimize slow crack growth effects. Conversely, testing canbe conducted in environments and testing modes and ratesrepresentative of service conditions to evaluate material per-formance under those conditions. When testing i
27、s conducted inuncontrolled ambient air with the objective of evaluatingmaximum strength potential, relative humidity and temperaturemust be monitored and reported. Testing at humidity levels65 % RH is not recommended and any deviations from thisrecommendation must be reported.6.2 Preparation of test
28、 specimens can introduce fabricationflaws which may have pronounced effects on the mechanicalproperties and behavior (for example, shape and level of theresulting force-displacement curve and shear strength). Ma-chining damage introduced during test specimen preparationcan be either a random interfe
29、ring factor in the determinationof shear strength of pristine material, or an inherent part of thestrength characteristics to be measured. Universal or standard-ized test methods of surface preparation do not exist. Finalmachining steps may, or may not, negate machining damageintroduced during the i
30、nitial machining. Thus, test specimenfabrication history may play an important role in the measuredstrength distributions and shall be reported.FIG. 1 Schematic of Uniaxial Compression of Double-NotchedTest Specimen for the Determination of Interlaminar ShearStrength of CFCCsC1425 1926.3 Bending in
31、uniaxially loaded shear tests can cause orpromote nonuniform stress distributions that may alter thedesired state of stress during the test. For example, nonuniformloading will occur if the loading surfaces of the test specimenare not flat and parallel.6.4 Fractures that initiate outside the gage se
32、ction of a testspecimen may be due to factors such as localized stressconcentrations, extraneous stresses introduced by improperloading configurations, or strength-limiting features in themicrostructure of the test specimen. Such non-gage sectionfractures will normally constitute invalid tests.6.5 F
33、or the evaluation of the interlaminar shear strength bythe uniaxial compression of a double-notched test specimen,the distance between the notches has an effect on the maximumforce and therefore on the interlaminar shear strength.3,4,5Ithas been found that the stress distribution in the gage section
34、 ofthe test specimen is independent of the distance between thenotches when the notches are far apart. However, when thedistance between the notches is such that the stress fieldsaround the notches interact, the measured interlaminar shearstrength increases. Because of the complexity of the stress f
35、ieldaround each notch and its dependence on the properties andhomogeneity of the material, conduct a series of tests on testspecimens with different spacing between the notches todetermine the effect of notch separation on the measuredinterlaminar shear strength.6.6 For the evaluation of the interla
36、minar shear strength bythe uniaxial compression of a double-notched test specimen,excessive clamping forces will reduce the stress concentrationaround the notches and, therefore, artificially increase themeasured interlaminar shear strength. Excessive clampingmight occur if interference between the
37、test fixture and the testspecimen results from mismatch in their thermal expansion.Paragraph 7.6 provides guidance to prevent this problem.6.7 The interlaminar shear strength of 1D and 2D CFCCs iscontrolled either by the matrix-rich interlaminar regions or bythe weakest of the fiber-matrix interface
38、s. Whetherinterlaminar-shear failure initiates at the matrix-rich interlami-nar region or at the weakest of the fiber/matrix interfacesdepends on the location of the root of the notch, or where theinterlaminar shear stress is largest, or with respect to theinterlaminar microstructural features, or c
39、ombinations thereof.7. Apparatus7.1 Testing MachinesThe testing machine shall be inconformance with Practices E4. The forces used in determiningshear strength shall be accurate within 61 % at any forcewithin the selected force range of the testing machine asdefined in Practices E4.7.2 Heating Appara
40、tusThe apparatus for, and method of,heating the test specimens shall provide the temperaturecontrol necessary to satisfy the requirement of 10.2.7.2.1 Heating can be radiative by indirect electrical resis-tance (heating elements), indirect induction through asusceptor, or radiant lamp with the test
41、specimen in ambient airat atmospheric pressure unless other environments are specifi-cally applied and reported. Note that conductive or directresistance heating is not recommended for heating CFCCs dueto possible differences of the electrical resistance of theconstituent materials which may produce
42、 nonuniform heatingof the test specimen.7.3 Temperature-Measuring ApparatusThe method oftemperature measurement shall be sufficiently sensitive andreliable to ensure that the temperature of the test specimen iswithin the limits specified in 10.2.7.3.1 Primary temperature measurement shall be made wi
43、ththermocouples in conjunction with potentiometers,millivoltmeters, or electronic temperature controllers or read-out units, or combinations thereof. Such measurements aresubject to two types of error. Thermocouple calibration andinstrument measuring errors initially produce uncertainty as tothe exa
44、ct temperature. Secondly, both thermocouples andmeasuring instruments may be subject to variations over time.Common errors encountered in the use of thermocouples tomeasure temperatures include: calibration error, drift in cali-bration due to contamination or deterioration with use, lead-wire error,
45、 error arising from method of attachment to the testspecimen, direct radiation of heat to the bead, heat conductionalong thermocouple wires, and so forth.7.3.2 Temperature measurements shall be made with ther-mocouples of known calibration. Representative thermo-couples shall be calibrated from each
46、 lot of wires used formaking noble-metal (for example, platinum or rhodium) ther-mocouples. Except for relatively low temperatures of exposure,noble-metal thermocouples are eventually subject to error uponreuse. Oxidized noble-metal thermocouples shall not be reusedwithout clipping back to remove wi
47、re exposed to the hot zone,re-welding, and annealing. Any reuse of noble-metal thermo-couples after relatively low-temperature use without this pre-caution shall be accompanied by re-calibration data demon-strating that calibration was not unduly affected by theconditions of exposure.7.3.3 Measureme
48、nt of the drift in calibration of thermo-couples during use is difficult. When drift is a problem duringtests, a method shall be devised to check the readings of thethermocouples monitoring the test specimen temperature dur-ing the test. For reliable calibration of thermocouples after use,the temper
49、ature gradient of the test furnace must be reproducedduring the re-calibration.7.3.4 Temperature measuring, controlling, and recordinginstruments shall be calibrated against a secondary standard,such as precision potentiometer, optical pyrometer, or black-body thyristor. Lead-wire error shall be checked with the leadwires in place as they normally are used. For thermocouple3Whitney, J. M., “Stress Analysis of the Double Notch Shear Specimen,”Proceedings of the American Society for Composites, 4th Technical Conference,Blacksburg, VA, Technomic Publishing Co., Oct. 35, 198
