1、Designation: C 1198 08Standard Test Method forDynamic Youngs Modulus, Shear Modulus, and PoissonsRatio for Advanced Ceramics by Sonic Resonance1This standard is issued under the fixed designation C 1198; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he 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 the dy-namic elastic properties of adva
3、nced ceramics. Specimens ofthese materials possess specific mechanical resonant frequen-cies that are determined by the elastic modulus, mass, andgeometry of the test specimen. Therefore, the dynamic elasticproperties of a material can be computed if the geometry, mass,and mechanical resonant freque
4、ncies of a suitable test speci-men of that material can be measured. Dynamic Youngsmodulus is determined using the resonant frequency in theflexural mode of vibration. The dynamic shear modulus, ormodulus of rigidity, is found using torsional resonant vibra-tions. Dynamic Youngs modulus and dynamic
5、shear modulusare used to compute Poissons ratio.1.2 This test method measures the resonant frequencies oftest specimens of suitable geometry by mechanically excitingthem at continuously variable frequencies. Mechanical excita-tion of the bars is provided through the use of a transducer thattransform
6、s a cyclic electrical signal into a cyclic mechanicalforce on the specimen.Asecond transducer senses the resultingmechanical vibrations of the specimen and transforms theminto an electrical signal. The amplitude and frequency of thesignal are measured by an oscilloscope or other means to detectreson
7、ant vibration in the desired mode. The resonant frequen-cies, dimensions, and mass of the specimen are used tocalculate dynamic Youngs modulus and dynamic shear modu-lus. (See Fig. 1)1.3 This test method is specifically appropriate for advancedceramics that are elastic, homogeneous, and isotropic (1
8、).2Advanced ceramics of a composite character (particulate,whisker, or fiber reinforced) may be tested by this test methodwith the understanding that the character (volume fraction,size, morphology, distribution, orientation, elastic properties,and interfacial bonding) of the reinforcement in the te
9、stspecimen will have a direct effect on the elastic properties.These reinforcement effects must be considered in interpretingthe test results for composites. This test method is notsatisfactory for specimens that have cracks or voids that aremajor discontinuities in the specimen. Neither is the test
10、method satisfactory when these materials cannot be fabricatedin a uniform rectangular or circular cross section.1.4 A high-temperature furnace and cryogenic cabinet aredescribed for measuring the dynamic elastic moduli as afunction of temperature from 195 to 1200C.1.5 Modification of this test metho
11、d for use in qualitycontrol is possible. A range of acceptable resonant frequenciesis determined for a specimen with a particular geometry andmass. Any specimen with a frequency response falling outsidethis frequency range is rejected. The actual modulus of eachspecimen need not be determined as lon
12、g as the limits of theselected frequency range are known to include the resonantfrequency that the specimen must possess if its geometry andmass are within specified tolerances.1.6 The procedures in this test method are, where possible,consistent with the procedures of Test Methods C 623, C 747,and
13、C 848. The tables of these test methods have been replacedby the actual formulas from the original references. With theadvent of computers and sophisticated hand calculators, theactual formulas can be easily used and provide greater accu-racy than factor tables.1.7 The values stated in SI units are
14、to be regarded as thestandard. The values given in parentheses are for informationonly.1.8 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
15、and determine the applica-bility of regulatory limitations prior to use.1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.01 onMechanical Properties and Performance.Current edition approved Jan. 1, 2008. Publish
16、ed January 2008. Originallyapproved in 1991. Last previous edition approved in 2001 as C 1198 01.2The boldface numbers given in parentheses refer to a list of references at theend of the text.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
17、States.Copyright by ASTM Intl (all rights reserved); Fri Apr 24 01:17:07 EDT 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.2. Referenced Documents2.1 ASTM Standards:3C 372 Test Method for Linear Thermal Expansion of Por-celain Enamel and
18、 Glaze Frits and Fired Ceramic Whitew-are Products by the Dilatometer MethodC 623 Test Method for Youngs Modulus, Shear Modulus,and Poissons Ratio for Glass and Glass-Ceramics byResonanceC 747 Test Method for Moduli of Elasticity and Fundamen-tal Frequencies of Carbon and Graphite Materials by Sonic
19、ResonanceC 848 Test Method for Youngs Modulus, Shear Modulus,and Poissons Ratio For Ceramic Whitewares by Reso-nanceC 1145 Terminology of Advanced CeramicsC 1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureD 4092 Terminology for Plastics: Dynamic MechanicalPropertiesE
20、 2001 Guide for Resonant Ultrasound Spectroscopy forDefect Detection in Both Metallic and Non-metallic Parts3. Terminology3.1 Definitions:3.1.1 advanced ceramic, na highly engineered, high per-formance, predominately nonmetallic, inorganic, ceramic ma-terial having specific functional attributes. C
21、11453.1.1.1 dynamic mechanical measurement, na techniquein which either the modulus or damping, or both, of a substanceunder oscillatory load or displacement is measured as afunction of temperature, frequency, or time, or combinationthereof. D 40923.1.2 elastic limit FL2, nthe greatest stress that a
22、material is capable of sustaining without permanent strainremaining upon complete release of the stress.3.1.3 elastic modulus FL2, nthe ratio of stress to strainbelow the proportional limit.3.1.4 Poissons ratio () nd, nthe absolute value of theratio of transverse strain to the corresponding axial st
23、rainresulting from uniformly distributed axial stress below theproportional limit of the material.3.1.4.1 DiscussionIn isotropic materials Youngs modu-lus (E), shear modulus (G), and Poissons ratio () are relatedby the following equation: 5 E/2G ! 2 13.1.5 proportional limit FL2, nthe greatest stres
24、s that amaterial is capable of sustaining without deviation fromproportionality of stress to strain (Hookes law).3.1.6 shear modulus (G) FL2, nthe elastic modulus inshear or torsion. Also called modulus of rigidity or torsionalmodulus.3.1.7 Youngs modulus ( E) FL2, nthe elastic modulusin tension or
25、compression.3.2 Definitions of Terms Specific to This Standard:3.2.1 anti-nodes, nan unconstrained slender rod or bar inresonance contains two or more locations that have localmaximum displacements, called anti-nodes. For the fundamen-tal flexure resonance, the anti-nodes are located at the two ends
26、and the center of the specimen.3.2.2 elastic, adjthe property of a material such that anapplication of stress within the elastic limit of that materialmaking up the body being stressed will cause an instantaneousand uniform deformation, that will be eliminated upon removalof the stress, with the bod
27、y returning instantly to its originalsize and shape without energy loss. Most advanced ceramicsconform to this definition well enough to make this resonancetest valid.3.2.3 flexural vibrations, nthe vibrations that occur whenthe oscillations in a slender rod or bar are in the plane normalto the leng
28、th dimension.3.2.4 homogeneous, adjthe condition of a specimen suchthat the composition and density are uniform, such that anysmaller specimen taken from the original is representative ofthe whole. Practically, as long as the geometrical dimensions ofthe test specimen are large with respect to the s
29、ize of individualgrains, crystals, or components, the body can be consideredhomogeneous.3.2.5 isotropic, adjthe condition of a specimen such thatthe values of the elastic properties are the same in all directionsin the material.Advanced ceramics are considered isotropic ona macroscopic scale, if the
30、y are homogeneous and there is arandom distribution and orientation of phases, crystallites, andcomponents.3.2.6 nodes, na slender rod or bar in resonance containsone or more locations having a constant zero displacement,called nodes. For the fundamental flexural resonance, the nodesare located at 0
31、.224 L from each end, where L is the length ofthe specimen.3.2.7 resonance, na slender rod or bar driven into one ofthe modes of vibration described in 3.2.3 or 3.2.9 is said to bein resonance when the imposed frequency is such that theresultant displacements for a given amount of driving force area
32、t a maximum. The resonant frequencies are natural vibrationfrequencies that are determined by the elastic modulus, mass,and dimensions of the test specimen.3.2.8 slender rod or bar, nin dynamic elastic propertytesting, a specimen whose ratio of length to minimum cross-sectional dimension is at least
33、 five and preferably in the rangeof 20 to 25.3.2.9 torsional vibrations, n the vibrations that occurwhen the oscillations in each cross-sectional plane of a slenderrod or bar are such that the plane twists around the lengthdimension axis.4. Summary of Test Method4.1 This test method measures the res
34、onant frequencies oftest specimens of suitable geometry by exciting them atcontinuously variable frequencies. Mechanical excitation ofthe bars is provided through the use of a transducer thattransforms a cyclic electrical signal into a cyclic mechanical3For referenced ASTM standards, visit the ASTM
35、website, www.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.C1198082Copyright by ASTM Intl (all rights reserved); Fri Apr 24 01:17:07 EDT 2009Downloaded/printed byGuo D
36、ehua (CNIS) pursuant to License Agreement. No further reproductions authorized.force on the specimen.Asecond transducer senses the resultingmechanical vibrations of the specimen and transforms theminto an electrical signal. The amplitude and frequency of thesignal are measured by an oscilloscope or
37、other means to detectresonance. The resonant frequencies, dimensions, and mass ofthe specimen are used to calculate dynamic Youngs modulusand dynamic shear modulus.5. Significance and Use5.1 This test method may be used for material development,characterization, design data generation, and quality c
38、ontrolpurposes. It is specifically appropriate for determining themodulus of advanced ceramics that are elastic, homogeneous,and isotropic.5.1.1 This test method is nondestructive in nature. Onlyminute stresses are applied to the specimen, thus minimizingthe possibility of fracture.5.1.2 The period
39、of time during which measurement stressis applied and removed is of the order of hundreds ofmicroseconds. With this test method it is feasible to performmeasurements at high temperatures, where delayed elastic andcreep effects would invalidate modulus measurements calcu-lated from static loading.5.2
40、 This test method has advantages in certain respects overthe use of static loading systems for measuring moduli inadvanced ceramics. It is nondestructive in nature and can beused for specimens prepared for other tests. Specimens aresubjected to minute strains; hence, the moduli are measured ator nea
41、r the origin of the stress-strain curve with the minimumpossibility of fracture. The period of time during whichmeasurement stress is applied and removed is of the order ofhundreds of microseconds. With this test method it is feasibleto perform measurements at high temperatures, where delayedelastic
42、 and creep effects would invalidate modulus measure-ments calculated from static loading.5.3 The sonic resonant frequency technique can also be usedas a nondestructive evaluation tool for detecting and screeningdefects (cracks, voids, porosity, density variations) in ceramicparts. These defects may
43、change the elastic response and theobserved resonant frequency of the test specimen. GuideE 2001 describes a procedure for detecting such defects inmetallic and nonmetallic parts using the resonant frequencymethod.6. Interferences6.1 The relationships between resonant frequency and dy-namic modulus
44、presented herein are specifically applicable tohomogeneous, elastic, isotropic materials.6.1.1 This test method of determining the moduli is appli-cable to composite ceramics and inhomogeneous materialsonly with careful consideration of the effect of inhomogeneitiesand anisotropy. The character (vol
45、ume fraction, size, morphol-ogy, distribution, orientation, elastic properties, and interfacialbonding) of the reinforcement/inhomogeneities in the speci-mens will have a direct effect on the elastic properties of thespecimen as a whole. These effects must be considered ininterpreting the test resul
46、ts for composites and inhomogeneousmaterials.6.1.2 If specific surface treatments (coatings, machining,grinding, etching, etc.) change the elastic properties of thenear-surface material, there will be accentuated effects on theproperties measured by this flexural method, as compared tostatic/bulk me
47、asurements by tensile or compression testing.6.1.3 This test method is not satisfactory for specimens thathave major discontinuities, such as large cracks (internal orsurface) or voids.6.2 This test method for determining moduli is limited tospecimens with regular geometries (rectangular parallelepi
48、pedand cylinders) for which analytical equations are available torelate geometry, mass, and modulus to the resonant vibrationfrequencies. This test method is not appropriate for determin-ing the elastic properties of materials which cannot be fabri-cated into such geometries.6.2.1 The analytical equ
49、ations assume parallel/concentricdimensions for the regular geometries of the specimen. Devia-tions from the specified tolerances for the dimensions of thespecimens will change the resonant frequencies and introduceerror into the calculations.6.2.2 Edge treatments such as chamfers or radii are notconsidered in the analytical equations. Edge chamfers onflexure bars prepared according to Test Method C 1161 willchange the resonant frequency of the test bars and introduceerror into the calculations of the dynamic modulus. It isre
