1、Designation:C84888(Reapproved 2016)Standard Test Method forYoungs Modulus,Shear Modulus,and Poissons Ratio ForCeramic Whitewares by Resonance1This standard is issued under the fixed designation C848;the number immediately following the designation indicates the year oforiginal adoption or,in the cas
2、e 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.Scope1.1 This test method covers the determination of the elasticproperties of ceramic whiteware materials
3、.Specimens of thesematerials possess specific mechanical resonance frequencieswhich are defined by the elastic moduli,density,and geometryof the test specimen.Therefore the elastic properties of amaterial can be computed if the geometry,density,and me-chanical resonance frequencies of a suitable tes
4、t specimen ofthat material can be measured.Youngs modulus is determinedusing the resonance frequency in the flexural mode of vibra-tion.The shear modulus,or modulus of rigidity,is found usingtorsional resonance vibrations.Youngs modulus and shearmodulus are used to compute Poissons ratio,the factor
5、oflateral contraction.1.2 All ceramic whiteware materials that are elastic,homogeneous,and isotropic may be tested by this test method.2This test method is not satisfactory for specimens that havecracks or voids that represent inhomogeneities in the material;neither is it satisfactory when these mat
6、erials cannot beprepared in a suitable geometry.NOTE1Elastic here means that an application of stress within theelastic limit of that material making up the body being stressed will causean instantaneous and uniform deformation,which will cease upon removalof the stress,with the body returning insta
7、ntly to its original size and shapewithout an energy loss.Many ceramic whiteware materials conform to thisdefinition well enough that this test is meaningful.NOTE2Isotropic means that the elastic properties are the same in alldirections in the material.1.3 A cryogenic cabinet and high-temperature fu
8、rnace aredescribed for measuring the elastic moduli as a function oftemperature from 195 to 1200C.1.4 Modification of the test for use in quality control ispossible.A range of acceptable resonance frequencies isdetermined for a piece with a particular geometry and density.Any specimen with a frequen
9、cy response falling outside thisfrequency range is rejected.The actual modulus of each pieceneed not be determined as long as the limits of the selectedfrequency range are known to include the resonance frequencythat the piece must possess if its geometry and density arewithin specified tolerances.1
10、.5 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.Summary of Test M
11、ethod2.1 This test method measures the resonance frequencies oftest bars of suitable geometry by exciting them at continuouslyvariable frequencies.Mechanical excitation of the specimen isprovided through use of a transducer that transforms an initialelectrical signal into a mechanical vibration.Anot
12、her trans-ducer senses the resulting mechanical vibrations of the speci-men and transforms them into an electrical signal that can bedisplayed on the screen of an oscilloscope to detect resonance.The resonance frequencies,the dimensions,and the mass of thespecimen are used to calculate Youngs modulu
13、s and the shearmodulus.3.Significance and Use3.1 This test system has advantages in certain respects overthe use of static loading systems in the measurement of ceramicwhitewares.3.1.1 Only minute stresses are applied to the specimen,thusminimizing the possibility of fracture.3.1.2 The period of tim
14、e during which stress is applied andremoved is of the order of hundreds of microseconds,makingit feasible to perform measurements at temperatures wheredelayed elastic and creep effects proceed on a much-shortenedtime scale.3.2 This test method is suitable for detecting whether amaterial meets specif
15、ications,if cognizance is given to oneimportant fact:ceramic whiteware materials are sensitive tothermal history.Therefore,the thermal history of a testspecimen must be known before the moduli can be considered1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and
16、Related Productsand is the direct responsibility of SubcommitteeC21.03 on Methods for Whitewares and Environmental Concerns.Current edition approved July 1,2016.Published July 2016.Originally approvedin 1976.Last previous edition approved in 2011 as C848 88(2011).DOI:10.1520/C0848-88R16.2Spinner,S.,and Tefft,W.E.,“A Method for Determining MechanicalResonance Frequencies and for Calculating Elastic Moduli from TheseFrequencies,”Proceedings,ASTM,1961,pp.12211238.Copyright ASTM International,100 Ba
