ASTM_E_132_-_04_2010.pdf

Designation:E13204(Reapproved 2010)Standard Test Method forPoissons Ratio at Room Temperature1This standard is issued under the fixed designation E132;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of Poissonsratio from tension tests of structural materials at room tem-perature.This test method is limited to specimens of rectan-gular section and to materials in which and stresses at whichcreep is negligible compared to the strain produced immedi-ately upon loading.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 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:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE8 Test Methods for Tension Testing of Metallic MaterialsE83 Practice for Verification and Classification of Exten-someter SystemsE111 Test Method for Youngs Modulus,Tangent Modulus,and Chord ModulusE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce Application3.Terminology3.1 Definitions:3.1.1 Poissons ratiothe negative of the ratio of transversestrain to the corresponding axial strain resulting from an axialstress below the proportional limit of the material.3.1.2 DiscussionAbove the proportional limit,the ratio oftransverse strain to axial strain will depend on the averagestress and on the stress range for which it is measured and,hence,should not be regarded as Poissons ratio.If this ratio isreported,nevertheless,as a value of“Poissons ratio”forstresses beyond the proportional limit,the range of stressshould be stated.3.1.3 DiscussionPoissons ratio will have more than onevalue if the material is not isotropic.Deviations from isotropyshould be suspected if the Poissons ratio,determined by themethod described below differs significantly from that deter-mined when the ratio E/G of Youngs modulus,E,to shearmodulus,G,is substituted in the following equation:5E/2G!2 1(1)where E and G must be measured with greater precisionthan the precision desired in the measurement of.4.Significance and Use4.1 When uniaxial force is applied to a solid,it deforms inthe direction of the applied force,but also expands or contractslaterally depending on whether the force is tensile or compres-sive.If the solid is homogeneous and isotropic,and thematerial remains elastic under the action of the applied force,the lateral strain bears a constant relationship to the axial strain.This constant,called Poissons ratio,is an intrinsic materialproperty just like Youngs modulus and Shear modulus.4.2 Poissons ratio is used for design of structures where alldimensional changes resulting from application of force needto be taken into account,and in the application of thegeneralized theory of elasticity to structural analysis.4.3 In this test method,the value of Poissons ratio isobtained from strains resulting from uniaxial stress only.5.General Considerations5.1 The accuracy of the determination of Poissons ratio isusually limited by the accuracy of the transverse strain mea-surements because the percentage errors in these measurementsare usually greater than in the axial strain measurements.Since1This test method is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved Sept.1,2010.Published November 2010.Originallyapproved in 1958.Last previous edition approved in 2004 as E132 04.DOI:10.1520/E0132-04R10.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 a ratio rather than an absolute quantity is measured,it is onlynecessary to know accurately the relative value of the calibra-tion factors of the extensometers.Also,in general,the values ofthe applied forces need not be accurately known.It is fre-quently expedient to make the determination of Poissons ratioconcurrently with determinations of Youngs modulus and