1、Designation: C 1341 06Standard Test Method forFlexural Properties of Continuous Fiber-ReinforcedAdvanced Ceramic Composites1This standard is issued under the fixed designation C 1341; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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 flexuralproperties of continuous fiber-reinforced ceramic c
3、ompositesin the form of rectangular bars formed directly or cut fromsheets, plates, or molded shapes. Three test geometries aredescribed as follows:1.1.1 Test Geometry IA three-point loading system utiliz-ing center point force application on a simply supported beam.1.1.2 Test Geometry IIAA four-poi
4、nt loading system uti-lizing two force application points equally spaced from theiradjacent support points with a distance between force applica-tion points of one half of the support span.1.1.3 Test Geometry IIBA four-point loading system uti-lizing two force application points equally spaced from
5、theiradjacent support points with a distance between force applica-tion points of one third of the support span.1.2 This test method applies primarily to all advancedceramic matrix composites with continuous fiber reinforce-ment: uni-directional (1-D), bi-directional (2-D), tri-directional(3-D), and
6、 other continuous fiber architectures. In addition, thistest method may also be used with glass (amorphous) matrixcomposites with continuous fiber reinforcement. However,flexural strength cannot be determined for those materials thatdo not break or fail by tension or compression in the outerfibers.
7、This test method does not directly address discontinuousfiber-reinforced, whisker-reinforced, or particulate-reinforcedceramics. Those types of ceramic matrix composites are bettertested in flexure using Test Methods C 1161 and C 1211.1.3 Tests can be performed at ambient temperatures or atelevated
8、temperatures. At elevated temperatures, a suitablefurnace is necessary for heating and holding the test specimensat the desired testing temperatures.1.4 This test method includes the following:SectionScope 1Referenced Documents 2Terminology 3Summary of Test Method 4Significance and Use 5Interference
9、s 6Apparatus 7Precautionary Statement 8Test specimens 9Procedures 10Calculation of Results 11Report 12Precision and Bias 13Keywords 14ReferencesCFCC Surface Condition andFinishingAnnex A1Conditions and Issues in HotLoading of Test specimensinto FurnacesAnnex A2Toe Compensation on Stress-Strain Curve
10、sAnnex A3Corrections for Thermal Ex-pansion in Flexural EquationsAnnex A4Example of Test Report Appendix X11.5 The values stated in SI units are to be regarded as thestandard in accordance with IEEE/ASTM SI 10.1.6 This standard does not purport to address all of thesafety concerns, if any, associate
11、d 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 1145 Terminology of Advanced CeramicsC 1161 Test Method for
12、Flexural Strength of AdvancedCeramics at Ambient TemperatureC 1211 Test Method for Flexural Strength of AdvancedCeramics at Elevated TemperaturesC 1239 Practice for Reporting Uniaxial Strength Data andEstimating Weibull Distribution Parameters for AdvancedCeramicsC 1292 Test Method for Shear Strengt
13、h of ContinuousFiber-Reinforced Advanced Ceramics at Ambient Tem-peraturesD 790 Test Methods for Flexural Properties of Unreinforced1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Composite
14、s.Current edition approved Jan. 1, 2006. Published January 2006. Originallyapproved in 1996. Last previous edition approved in 2005 as C 1341 00 (2005).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
15、ndards 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.and Reinforced Plastics and Electrical Insulating MaterialsD 2344/D 2344M Test Method for Shor
16、t-Beam Strength ofPolymer Matrix Composite Materials and Their LaminatesD 3878 Terminology for Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods
17、E 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI 10
18、 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminology3.1 DefinitionsThe definitions of terms relating to flexuretesting appearing in Terminology E6apply to the terms used inthis test method. The definitions of terms relating to advancedce
19、ramics appearing in Terminology C 1145 apply to the termsused in this test method. The definitions of terms relating tofiber-reinforced composites appearing in Terminology D 3878apply to the terms used in this test method. Pertinent definitionsas listed in Test Method C 1161, Test Methods D 790, Ter
20、mi-nology C 1145, Terminology D 3878, and Terminology E6areshown in the following with the appropriate source given inbrackets. Additional terms used in conjunction with this testmethod are also defined in the following.3.1.1 advanced ceramic, nhighly engineered, high-performance, predominately nonm
21、etallic, inorganic, ceramicmaterial having specific functional attributes. C 11453.1.2 breaking force, n FThe force at which fractureoccurs. (In this test method, fracture consists of breakage of thetest bar into two or more pieces or a loss of at least 20 % of themaximum force carrying capacity.) E
22、63.1.3 ceramic matrix composite, nmaterial consisting oftwo or more materials (insoluble in one another) in which themajor, continuous component (matrix component) is a ceramic,while the secondary component(s) (reinforcing component)may be ceramic, glass-ceramic, glass, metal, or organic innature. T
23、hese components are combined on a macroscale toform a useful engineering material possessing certain proper-ties or behavior not possessed by the individual constituents.3.1.4 continuous fiber-reinforced ceramic composite(CFCC), nceramic matrix composite in which the reinforc-ing phase consists of a
24、 continuous fiber, continuous yarn, or awoven fabric.3.1.5 flexural strength, n FL2measure of the ultimatestrength of a specified beam in bending. C 11613.1.6 four-point-13 point flexure, na configuration offlexural strength testing where a test specimen is symmetricallyloaded at two locations that
25、are situated one third of the overallspan away from the outer two support bearings.3.1.7 four-point-14 point flexure, na configuration offlexural strength testing where a test specimen is symmetricallyloaded at two locations that are situated one quarter of theoverall span away from the outer two su
26、pport bearings.C 11613.1.8 fracture strength, n FL2the calculated flexuralstress at the breaking force.3.1.9 modulus of elasticity, n FL2the ratio of stress tocorresponding strain below the proportional limit. E63.1.10 proportional limit stress, n FL2greatest stressthat a material is capable of sust
27、aining without any deviationfrom proportionality of stress to strain (Hookes law).3.1.10.1 DiscussionMany experiments have shown thatvalues observed for the proportional limit vary greatly with thesensitivity and accuracy of the testing equipment, eccentricityof force application, the scale to which
28、 the stress-straindiagram is plotted, and other factors. When determination ofproportional limit is required, the procedure and sensitivity ofthe test equipment shall be specified. E63.1.11 slow crack growth, nsubcritical crack growth (ex-tension) that may result from, but is not restricted to, such
29、mechanisms as environmentally assisted stress corrosion ordiffusive crack growth.3.1.12 span-to-depth ratio, n ndfor a particular testspecimen geometry and flexure test configuration, the ratio(L/d) of the outer support span length (L) of the flexure testspecimen to the thickness/depth (d) of test s
30、pecimen (as usedand described in Test Method D 790).3.1.13 three-point flexure, na configuration of flexuralstrength testing where a test specimen is loaded at a locationmidway between two support bearings. C 11614. Summary of Test Method4.1 A bar of rectangular cross section is tested in flexure as
31、a beam as in one of the following three geometries:4.1.1 Test Geometry IThe bar rests on two supports andforce is applied by means of a loading roller midway betweenthe supports (see Fig. 1.)4.1.2 Test Geometry IIAThe bar rests on two supports andforce is applied at two points (by means of two inner
32、 rollers),each an equal distance from the adjacent outer support point.FIG. 1 Flexural Test GeometriesC1341062The inner support points are situated one quarter of the overallspan away from the outer two support bearings. The distancebetween the inner rollers (that is, the load span) is one half ofth
33、e support span (see Fig. 1).4.1.3 Test Geometry IIBThe bar rests on two supports andforce is applied at two points (by means of two loading rollers),situated one third of the overall span away from the outer twosupport bearings. The distance between the inner rollers (thatis, the inner support span)
34、 is one third of the outer support span(see Fig. 1).4.2 The test specimen is deflected until rupture occurs in theouter fibers or until there is a 20 % decrease from the peakforce.4.3 The flexural properties of the test specimen (flexuralstrength and strain, fracture strength and strain, modulus ofe
35、lasticity, and stress-strain curves) are calculated from theforce and deflection using elastic beam equations.5. Significance and Use5.1 This test method is used for material development,quality control, and material flexural specifications. Althoughflexural test methods are commonly used to determi
36、ne designstrengths of monolithic advanced ceramics, the use of flexuretest data for determining tensile or compressive properties ofCFCC materials is strongly discouraged. The nonuniformstress distributions in the flexure test specimen, the dissimilarmechanical behavior in tension and compression fo
37、r CFCCs,low shear strengths of CFCCs, and anisotropy in fiber archi-tecture all lead to ambiguity in using flexure results for CFCCmaterial design data (1-4). Rather, uniaxial-forced tensile andcompressive tests are recommended for developing CFCCmaterial design data based on a uniformly stressed te
38、st condi-tion.5.2 In this test method, the flexure stress is computed fromelastic beam theory with the simplifying assumptions that thematerial is homogeneous and linearly elastic. This is valid forcomposites where the principal fiber direction is coincident/transverse with the axis of the beam. The
39、se assumptions arenecessary to calculate a flexural strength value, but limit theapplication to comparative type testing such as used formaterial development, quality control, and flexure specifica-tions. Such comparative testing requires consistent and stan-dardized test conditions, that is, test s
40、pecimen geometry/thickness, strain rates, and atmospheric/test conditions.5.3 Unlike monolithic advanced ceramics which fracturecatastrophically from a single dominant flaw, CFCCs generallyexperience “graceful” fracture from a cumulative damageprocess. Therefore, the volume of material subjected to
41、auniform flexural stress may not be as significant a factor indetermining the flexural strength of CFCCs. However, the needto test a statistically significant number of flexure test speci-mens is not eliminated. Because of the probabilistic nature ofthe strength of the brittle matrices and of the ce
42、ramic fiber inCFCCs, a sufficient number of test specimens at each testingcondition is required for statistical analysis, with guidelines forsufficient numbers provided in 9.7. Studies to determine theexact influence of test specimen volume on strength distribu-tions for CFCCs are not currently avai
43、lable.5.4 The four-point loading geometries (Geometries IIA andIIB) are preferred over the three-point loading geometry(Geometry I). In the four-point loading geometry, a largerportion of the test specimen is subjected to the maximumtensile and compressive stresses, as compared to the three-point lo
44、ading geometry. If there is a statistical/Weibull charac-ter failure in the particular composite system being tested, thesize of the maximum stress region will play a role in deter-mining the mechanical properties. The four-point geometrymay then produce more reliable statistical data.5.5 Flexure te
45、sts provide information on the strength anddeformation of materials under complex flexural stress condi-tions. In CFCCs nonlinear stress-strain behavior may developas the result of cumulative damage processes (for example,matrix cracking, matrix/fiber debonding, fiber fracture, delami-nation, etc.)
46、which may be influenced by testing mode, testingrate, processing effects, or environmental influences. Some ofthese effects may be consequences of stress corrosion orsubcritical (slow) crack growth which can be minimized bytesting at sufficiently rapid rates as outlined in 10.3 of this testmethod.5.
47、6 Because of geometry effects, the results of flexure testsof test specimens fabricated to standardized test dimensionsfrom a particular material or selected portions of a component,or both, cannot be categorically used to define the strength anddeformation properties of the entire, full-size end pr
48、oduct or itsin-service behavior in different environments. The effects ofsize and geometry shall be carefully considered in extrapolat-ing the test results to other configurations and performanceconditions.5.7 For quality control purposes, results from standardizedflexure test specimens may be consi
49、dered indicative of theresponse of the material lot from which they were taken withthe given primary processing conditions and post-processingheat treatments.5.8 The flexure behavior and strength of a CFCC aredependent on its inherent resistance to fracture, the presence offracture sources, or damage accumulation processes or combi-nation thereof. Analysis of fracture surfaces and fractography,though beyond the scope of this test method, is highlyrecommended.6. Interferences6.1 A CFCC material tested in flexure may fail in a varietyof distinct f
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