ASTM_C_747_-_16.pdf

Designation:C74716An American National StandardStandard Test Method forModuli of Elasticity and Fundamental Frequencies ofCarbon and Graphite Materials by Sonic Resonance1This standard is issued under the fixed designation C747;the number immediately following the designation indicates the year oforiginal adoption 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 covers determination of the dynamicelastic properties of isotropic and near isotropic carbon andgraphite materials at ambient temperatures.Specimens of thesematerials possess specific mechanical resonant frequencies thatare determined by the elastic modulus,mass,and geometry ofthe test specimen.The dynamic elastic properties of a materialcan therefore be computed if the geometry,mass,and mechani-cal resonant frequencies of a suitable(rectangular or cylindri-cal)test specimen of that material can be measured.DynamicYoungs modulus is determined using the resonant frequencyin the flexural or longitudinal mode of vibration.The dynamicshear modulus,or modulus of rigidity,is found using torsionalresonant vibrations.Dynamic Youngs modulus and dynamicshear modulus are used to compute Poissons ratio.1.2 This test method determines elastic properties by mea-suring the fundamental resonant frequency of test specimens ofsuitable geometry by exciting them mechanically by a singularelastic strike with an impulse tool.Specimen supports,impulselocations,and signal pick-up points are selected to induce andmeasure specific modes of the transient vibrations.A trans-ducer(for example,contact accelerometer or non-contactingmicrophone)senses the resulting mechanical vibrations of thespecimen and transforms them into electric signals.(See Fig.1.)The transient signals are analyzed,and the fundamentalresonant frequency is isolated and measured by the signalanalyzer,which provides a numerical reading that is(or isproportional to)either the frequency or the period of thespecimen vibration.The appropriate fundamental resonantfrequencies,dimensions,and mass of the specimen are used tocalculate dynamic Youngs modulus,dynamic shear modulus,and Poissons ratio.AnnexA1 contains an alternative approachusing continuous excitation.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C215 TestMethodforFundamentalTransverse,Longitudinal,and Torsional Resonant Frequencies ofConcrete SpecimensC559 Test Method for Bulk Density by Physical Measure-ments of Manufactured Carbon and Graphite ArticlesC885 Test Method for Youngs Modulus of RefractoryShapes by Sonic ResonanceC1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureE111 Test Method for Youngs Modulus,Tangent Modulus,and Chord ModulusE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod DilatometerE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 antinodes,ntwo or more locations that have localmaximum displacements,called antinodes,in an unconstrainedslender rod or bar in resonance.For the fundamental flexureresonance,the antinodes are located at the two ends and thecenter of the specimen.3.1.2 elastic modulusthe ratio of stress to strain,in thestress range where Hookes law is valid.3.1.3 flexural vibrations,nthe vibrations that occur whenthe displacements in a slender rod or bar are in a plane normalto the length dimension.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Oct.1,2016.Published January 2017.Originallyapproved in 1974.Last previous edition approved in 2010 as C747 93(2010)1.DOI:10.1520/C0747-16.2For referenced ASTM standards,visit the ASTM 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.*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 international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevel