ASTM_C_623_-_92_2015.pdf

Designation:C62392(Reapproved 2015)Standard Test Method forYoungs Modulus,Shear Modulus,and Poissons Ratio forGlass and Glass-Ceramics by Resonance1This standard is issued under the fixed designation C623;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.Scope1.1 This test method covers the determination of the elasticproperties of glass and glass-ceramic materials.Specimens ofthese materials possess specific mechanical resonance frequen-cies which are defined by the elastic moduli,density,andgeometry of the test specimen.Therefore the elastic propertiesof a material can be computed if the geometry,density,andmechanical resonance frequencies of a suitable test specimenof that material can be measured.Youngs modulus is deter-mined using the resonance frequency in the flexural mode ofvibration.The shear modulus,or modulus of rigidity,is foundusing torsional resonance vibrations.Youngs modulus andshear modulus are used to compute Poissons ratio,the factorof lateral contraction.1.2 All glass and glass-ceramic materials that are elastic,homogeneous,and isotropic may be tested by this test method.2The test method is not satisfactory for specimens that havecracks or voids that represent inhomogeneities in the material;neither is it satisfactory when these materials 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 instantly to its original size and shapewithout an energy loss.Glass and glass-ceramic 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.Glass is isotropic and glass-ceramics are usuallyso on a macroscopic scale,because of random distribution and orientationof crystallites.1.3 A cryogenic cabinet and high-temperature furnace 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 frequency 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.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 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 Method2.1 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.Another 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 reasonance frequencies,the dimensions,and the mass ofthe specimen are used to calculate Youngs modulus and theshear modulus.3.Significance and Use3.1 This test system has advantages in certain respects overthe use of static loading systems in the measurement of glassand glass-ceramics:3.1.1 Only minute stresses are applied to the specimen,thusminimizing the possibility of fracture.3.1.2 The period of time 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,as in the transformation range of glass,for instance.1This test method is under the jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subcommittee C14.04 onPhysical and Mechanical Properties.Current edition approved May 1,2015.Published May 2015.Originallyapproved in 1969.Last previous edition approved in 2010 as C623 92(2010).DOI:10.1520/C0623-92R15.2Spinner,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