1、Designation: C1468 06C1468 13Standard Test Method forTransthickness Tensile Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperature1This standard is issued under the fixed designation C1468; 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 Scope*1.1 This test method covers the determination of transthickness tensil
3、e strength SUT! under monotonic uniaxial forcing ofcontinuous fiber-reinforced ceramics (CFCC) at ambient temperature. This test method addresses, but is not restricted to, varioussuggested test specimen geometries, test fixtures, data collection and reporting procedure. In general, round or square
4、testspecimens are tensile tested in the direction normal to the thickness by bonding appropriate hardware to the samples andperforming the test. For a Cartesian coordinate system, the x-axis and the y-axis are in the plane of the test specimen. Thetransthickness direction is normal to the plane and
5、is labeled the z-axis for this test method. For CFCCs, the plane of the testspecimen normally contains the larger of the three dimensions and is parallel to the fiber layers for uni-directional, bi-directional,and woven composites. Note that transthickness tensile strength as used in this test metho
6、d refers to the tensile strength obtainedunder monotonic uniaxial forcing where monotonic refers to a continuous nonstop test rate with no reversals from test initiationto final fracture.1.2 This test method is intended primarily for use with all advanced ceramic matrix composites with continuous fi
7、berreinforcement: unidirectional (1-D), bidirectional (2-D), woven, and tridirectional (3-D). In addition, this test method also may beused with glass (amorphous) matrix composites with 1-D, 2-D, and 3-D continuous fiber reinforcement. This test method does notaddress directly discontinuous fiber-re
8、inforced, whisker-reinforced or particulate-reinforced ceramics, although the test methodsdetailed here may be equally applicable to these composites. It should be noted that 3-D architectures with a high volume fractionof fibers in the “z” direction may be difficult to test successfully.1.3 Values
9、are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and d
10、etermine the applicability of regulatorylimitations prior to use. Additional recommendations are provided in 6.7 and Section 7.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1239 Practice for Reporting Uniaxial Strength Data and Estimating Weibull Distribution Para
11、meters for Advanced CeramicsC1275 Test Method for Monotonic Tensile Behavior of Continuous Fiber-Reinforced Advanced Ceramics with SolidRectangular Cross-Section Test Specimens at Ambient TemperatureC1468 Test Method for Transthickness Tensile Strength of Continuous Fiber-Reinforced Advanced Ceramic
12、s at AmbientTemperatureD3878 Terminology for Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE337 Test Method for Measuring Humidity with a Psyc
13、hrometer (the Measurement of Wet- and Dry-Bulb Temperatures)E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method1 This test method is under the jurisdiction of ASTM Committee C28 on Advanced Ceramics and is the direct responsibility of Subcommittee C28.07
14、 on Ceramic MatrixComposites.Current edition approved Jan. 1, 2006Feb. 15, 2013. Published January 2006April 2013. Originally approved in 2000. Last previous edition approved in 20002006 asC1468 00.C1468 06. DOI: 10.1520/C1468-06.10.1520/C1468-13.2 For referencedASTM standards, visit theASTM website
15、, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication o
16、f what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considere
17、d the official document.*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 States1IEEE/ASTM SI 10 American National Standard for Use of the International System of Units (SI): The
18、 Modern Metric System.E1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial ForceApplication3. Terminology3.1 Definitions:3.1.1 The definitions of terms relating to tensile testing appearing in Terminology E6 apply to the terms used in this test
19、method.The definitions of terms relating to advanced ceramics appearing inTerminology C1145 apply to the terms used in this test method.The definitions of terms relating to fiber-reinforced composites appearing in Terminology D3878 apply to the terms used in thistest method. Pertinent definitions as
20、 listed in Practice E1012, Terminology C1145, Terminology D3878, and Terminology E6 areshown in the following with the appropriate source given in brackets. Terms used in conjunction with this test method are definedas follows:3.1.2 advanced ceramic, na highly-engineered, high-performance predominat
21、ely nonmetallic, inorganic, ceramic materialhaving specific functional attributes. C11453.1.3 bending strain, nthe difference between the strain at the surface and the axial strain. E10123.1.4 breaking force, nthe force at which fracture occurs, Pmax, is the breaking force in units of N. E63.1.5 cer
22、amic matrix composite (CMC), na material consisting of two or more materials (insoluble in one another), in whichthe major, continuous component (matrix component) is a ceramic, while the secondary component(s) (reinforcing component)may be ceramic, glass-ceramic, glass, metal or organic in nature.
23、These components are combined on a macroscale to form a usefulengineering material possessing certain properties or behavior not possessed by the individual constituents. C11453.1.6 continuous fiber-reinforced ceramic matrix composite (CFCC), na ceramic matrix composite in which the reinforcingphase
24、s consists of continuous filaments, fibers, yarn, or knitted or woven fabrics. C11453.1.7 gage length, nthe original length LGL of that portion of the test specimen over which strain or change of length isdetermined. E63.1.8 modulus of elasticity, nthe ratio of stress to corresponding strain below t
25、he proportional limit. E63.1.9 percent bending, nthe bending strain times 100 divided by the axial strain. E10123.1.10 tensile strength, nthe maximum tensile stress, which a material is capable of sustaining. Tensile strength is calculatedfrom the maximum force during a tension test carried to ruptu
26、re and the original cross-sectional area of the test specimen. E63.2 Definitions of Terms Specific to This Standard:3.2.1 transthickness, nthe direction parallel to the thickness, that is, out-of-plane dimension, as identified in 1.1, and alsotypically normal to the plies for 1-D, 2-D laminate, and
27、woven cloth. For 3-D laminates this direction is typically taken to benormal to the thickness and associated with the “z” direction.3.2.2 fixturing, nfixturing is referred to as the device(s) bonded to the test specimen. It is this device(s) that is actually grippedor pinned to the force train. The
28、fixturing transmits the applied force to the test specimen.4. Significance and Use4.1 This test method may be used for material development, material comparison, quality assurance, characterization, anddesign data generation.4.2 Continuous fiber-reinforced ceramic matrix composites generally are cha
29、racterized by fine grain sized (65 %RH is not recommended and any deviations from this recommendation must be reported.5.2 Surface and edge preparation of test specimens, although normally not considered a major concern in CFCCs, can introducefabrication flaws which may have pronounced effects on th
30、e measured transthickness strength (1).3 Machining damage introducedduring test specimen preparation can be either a random interfering factor in the determination of strength of pristine material, thatis, increased frequency of surface-initiated fractures compared to volume-initiated fractures, or
31、an inherent part of the strengthcharacteristics. Universal or standardized test methods of surface and edge preparation do not exist. It should be understood thatfinal machining steps may, or may not, negate machining damage introduced during the initial machining; thus, test specimenfabrication his
32、tory may play an important role in the measured strength distributions and should be reported. In addition, the natureof fabrication used for certain composites, for example, chemical vapor infiltration or hot pressing, may require the testing of testspecimens in the as-processed condition.5.3 Bendi
33、ng in uniaxial transthickness tensile tests can cause or promote nonuniform stress distributions with maximum stressesoccurring at the test specimen edge leading to nonrepresentative fractures. Similarly, fracture from edge flaws may be accentuatedor suppressed by the presence of the nonuniform stre
34、sses caused by bending.NOTE 1Finite element calculations were performed for the square cross section test specimen for the forcing conditions and test specimen thicknessinvestigated in reference (1). Stress levels along the four corner edges were found to be lower than the interior, except for the c
35、orners at the bond lineswhere the stress was slightly higher than the interior. Stress levels along the sides and interior of the test specimen were found to be uniform.6. Apparatus6.1 Testing MachinesMachines used for transthickness tensile testing shall conform to the requirements of Practice E4.
36、Theforces used in determining tensile strength shall be accurate within 61 % at any force within the selected force range of the testingmachine as defined in Practice E4. A schematic showing pertinent features of the transthickness tensile testing apparatus for twopossible forcing configurations is
37、shown in Figs. 1 and 2.6.1.1 Values for transthickness tensile strength can range a great deal for different types of CFCC. Therefore, it is helpful toknow an expected strength value in order to properly select a force range. Approximate transthickness tensile strength values (1)for several CFCCs ar
38、e as follows: porous oxide/oxide composites range from 210 MPa, hot pressed fully dense SiC/MAS-5glass-ceramic composites range from 1427 MPa, Polymer Infiltrated and Pyrolyzed (PIP) SiC/SiNC range from 1532 MPa, andhot pressed SCS-6/Si3N4 range from 3043 MPa.6.1.2 For any testing apparatus, the for
39、ce train will need to be aligned for angularity and concentricity.Alignment of the testingsystem will need to be measured and is detailed in A1.1 of Test Method C1275.6.2 Gripping Devices:6.2.1 GeneralVarious types of gripping devices may be used to transmit the force applied by the testing machine
40、to the testfixtures and into the test specimens. The brittle nature of the matrices of CFCCs requires accurate alignment. Bending momentscan produce stresses leading to premature crack initiation and fracture of the test specimen. Gripping devices can be classifiedgenerally as those employing active
41、 and those employing passive grip interfaces as discussed in the following sections. Severaladditional gripping techniques are discussed in Test Method C1275.3 The boldface numbers in parentheses refers to the list of references at the end of this standard.C1468 1336.2.1.1 Active Grip InterfacesActi
42、ve grip interfaces require a continuous application of a mechanical, hydraulic, or pneumaticforce to transmit the force applied by the test machine to the test fixtures. Generally, these types of grip interfaces cause a forceto be applied normal to the surface of the gripped section of the test fixt
43、uring. Transmission of the uniaxial force applied by thetest machine then is accomplished by friction between the test fixturing and the grip faces; thus, important aspects of active gripinterfaces are uniform contact between the gripped section of the test fixturing and the grip faces and constant
44、coefficient of frictionover the grip/fixture interface. In addition, for active grips, uniform application of gripping force and motion of the grips uponactuation are important factors to consider in assuring proper gripping.(1) Face-forceed grips, either by direct lateral pressure grip faces (2) or
45、 by indirect wedge-type grip faces, act as the gripinterface (3). Generally, close tolerances are required for the flatness and parallelism as well as for the wedge angle of the wedgegrip faces. In addition, the thickness, flatness, and parallelism of the gripped section of the fixturing shall be wi
46、thin similarly closetolerances to promote uniform contact at the fixture/grip interface. Tolerances will vary depending on the exact configuration.(2) Sufficient lateral pressure should be applied to prevent slippage between the grip face and the fixturing. Grip surfaces thatare scored or serrated w
47、ith a pattern similar to that of a single-cut file have been found satisfactory. A fine serration appears to bethe most satisfactory. The serrations should be kept clean and well defined but not overly sharp. The length L and width W ofthe grip faces should be equal to or greater than the respective
48、 length and width of the fixturing to be gripped.FIG. 1 Schematic Diagram of One Possible Apparatus for Conducting a Uniaxially-Forced Transthickness Tensile TestFIG. 2 Schematic Diagram of a Second Possible Apparatus for Conducting a Uniaxially-Forced Transthickness Tensile TestC1468 134(3) Grip in
49、serts, called wedges, can be machined to accept flat or round fixturing. This allows for a wide range of fixturingto be utilized.6.2.1.2 Passive Grip InterfacesPassive grip interfaces transmit the force applied by the test machine through a directmechanical link (4). Generally, these mechanical links transmit the test forces to the test specimen via geometrical features of thetest fixturing. Passive grips may act through pin forcing via pins at holes in the fixturing. Generally, close tolerances of lineardimensions are required to p
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