ASTM E132-17 Standard Test Method for Poisson’s Ratio at Room Temperature.pdf

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1、Designation: E132 17Standard 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 parenth

2、eses 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 te

3、nsion 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

4、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

5、user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established

6、in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology

7、Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE8 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

8、 Chord ModulusE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce Application3. Terminology3.1 Definitions:Terms common to mechanical testing.3.1.1 The definitions of mechanical testing terms that ap-pear in Terminology E6 apply to this t

9、est method. These termsinclude extensometer and stress-strain diagram.3.1.2 In addition, the following common terms that appearin Terminology E6 apply to this test method.3.1.3 The terms accuracy, bias, and precision are used asdefined in E177.3.1.4 axial strain, nlinear strain in a plane parallel t

10、o thelongitudinal axis of the specimen.3.1.5 Poissons ratio, , nthe negative of the ratio oftransverse strain to the corresponding axial strain resultingfrom an axial stress below the proportional limit of thematerial.3.1.5.1 DiscussionPoissons ratio may be negative forsome materials. For example, a

11、 tensile transverse strain willresult from a tensile axial strain.3.1.5.2 DiscussionPoissons ratio will have more than onevalue if the material is not isotropic.3.1.6 proportional limit, FL-2, nthe greatest stress that amaterial is capable of sustaining without any deviation fromproportionality of s

12、tress to strain (Hookes Law).3.1.6.1 DiscussionMany experiments have shown thatvalues observed for the proportional limit vary greatly with thesensitivity and accuracy of the testing equipment, eccentricityof loading, the scale to which the stress-strain diagram isplotted, and other factors. When de

13、termination of the propor-tional limit is required, the procedure and the sensitivity of thetest equipment should be specified.3.1.7 transverse strain, t,nlinear strain in a plane per-pendicular to the axis of the specimen.3.1.7.1 DiscussionTransverse strain may differ with direc-tion in anisotropic

14、 materials.3.2 Definitions of Terms Specific to This Standard:1This 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 July 15, 2017. Published September 2017. Originally

15、approved in 1958. Last previous edition approved in 2010 as E132 04(2010). DOI:10.1520/E0132-17.2For 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 Docume

16、nt Summary page onthe ASTM website.Copyright 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 Pri

17、nciples for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.1 longitudinal strain, l,nthe strain in the direction ofthe major axis of the specimen and parallel to the direction ofthe applied

18、 uniaxial force.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

19、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 alldimensiona

20、l 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.4.4 Above the proportional

21、 limit, the ratio of transversestrain to axial strain will depend on the average stress and onthe stress range for which it is measured and, hence, should notbe regarded as Poissons ratio. If this ratio is reported,nevertheless, as a value of “Poissons ratio” for stresses belowthe proportional limit

22、, the range of stress should be reported.4.5 Deviations from isotropy should be suspected if thePoissons ratio, , determined by the method described belowdiffers significantly from that determined when the ratio E/G ofYoungs modulus, E, to shear modulus, G, is substituted in thefollowing equation: 5

23、 E/2G! 2 1 (1)where E and G must be measured with greater precisionthan the precision desired in the measurement of .4.6 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

24、 usually greater than in the axial strain measurements. Sincea 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

25、. It is fre-quently expedient to make the determination of Poissons ratioconcurrently with determinations of Youngs modulus and theproportional limit.5. Apparatus5.1 ForcesForces shall be applied either by verified deadweights or in a testing machine that has been calibrated inaccordance with Practi

26、ces E4.5.2 ExtensometersClass B-1 extensometers or better, asdescribed in Practice E83, shall be used except as otherwiseprovided in the product specifications.NOTE 1If exceptions are provided in the product specification so thatextensometers of types other than those covered in Practice E83 are use

27、d,it may be necessary to apply corrections, for example, the correction forthe transverse sensitivity3of bonded resistance gages.5.2.1 At least two pairs of extensometers should be usedone pair for measuring longitudinal strain and the other fortransverse strain, with the extensometers of each pair

28、parallelto each other and on opposite sides of the specimen.Additionalextensometers may be used to check on alignment or to obtainbetter average strains in the case of unavoidable variations inthickness. The extensometers should be placed on the speci-men with a free distance of at least one specime

29、n widthbetween any extensometer and the nearest fillet, and at leasttwo specimen widths between any extensometer and thenearest grip.NOTE 2Three possible arrangements of extensometers, among themany that have been used, are shown in Fig. 1. Arrangement (a), Fig. 1,which requires only two pairs of ex

30、tensometers, can be used if theconditions are very nearly ideal with respect to axiality of applied forceand constancy of cross-section within the length in which the extensom-eters are placed. An additional pair of extensometers is used in arrange-ment (b) to provide some compensation for the effec

31、t of a uniformvariation in thickness in the longitudinal direction. The other arrangementof three pairs of extensometers, arrangement (c), provides a check onalignment.5.3 Alignment DevicesGrips and other devices for obtain-ing and maintaining axial alignment are shown in Test MethodsE8.6. Test Spec

32、imens6.1 Selection and Preparation of SpecimensSelect andprepare test specimens that are straight and uniform in thick-ness and representative of the material being tested.6.2 DimensionsThe tested length of the specimen shouldbe at least five times the tested width, and the length betweenthe grips s

33、hould be seven times the tested width. The testedwidth shall be least equal to the tested thickness. The radius ofthe fillets shall not be not less than the minimum width of thespecimen. The width shall be constant over the entire lengthwhere the extensometers are placed and for an additional3Perry,

34、 C. C., and Lissner, H. R., The Strain Gage Primer, McGraw-Hill BookCo., New York, NY, 1955, pp. 141146.NOTE 1Each symbol indicates the location of a pair of extensometerson opposite sides of the specimen.FIG. 1 Three Possible Arrangements of ExtensometersE132 172distance at each end equal to at lea

35、st this width, unlessotherwise provided in the product specifications.6.3 Stress ReliefThe specimen shall be free of residualstresses. The specimen may be subjected to an annealingprocedure to relieve residual stresses. If the intent of the test isto verify the performance of a product, the annealin

36、g proceduremay be omitted. Report the condition of the material tested,including any annealing procedure.NOTE 3This test method is intended to produce intrinsic materialsproperties. An annealing procedure at Tm/3 for 30 min (Tmis the meltingpoint of the material in K) has been suitable for relieving

37、 residual stresses.7. Procedure7.1 Measurement of SpecimensAll surfaces on the rectan-gular specimen shall be flat. Opposite surfaces across the widthand thickness shall be parallel within 0.001 in. (0.025 mm) and0.0001 in. (0.0025 mm) respectively. Specimen thickness shallbe measured to within 0.00

38、1 in. (0.025 mm) and width shall bemeasured to within 0.0001 in. (0.0025 mm) at three locationsand an average determined.NOTE 4For thin sheet, a survey of thickness variation by moresensitive devices, such as a pneumatic or electric gage, may be needed todetermine thickness with the required accurac

39、y.7.2 AlignmentThe alignment of the testing machine andfixtures shall meet Practice E1012, Class 5.7.3 Record simultaneous measurements of applied force andstrain.7.4 Speed of TestingThe speed of testing shall be lowenough to make the thermal effects of adiabatic expansion orcontraction negligible,

40、yet high enough to make creep negli-gible. In applying forces with dead weights, avoid temporaryoverloading due to inertia of the weights.7.5 Applied ForcesThe applied forces shall correspond tostresses that are within the linear portion of the stress-straincurve, that is, less than the proportional

41、 limit. The precision ofthe value of Poissons ratio obtained will depend on the numberof data pair of longitudinal and transverse strain taken (see Fig.2).7.6 Strain ReadingsRead all extensometers at the sameapplied force.7.7 TemperatureRecord the temperature. Avoid changesin temperature during the

42、test.8. Evaluation of Data8.1 Plot the average longitudinal strain, l, indicated by thelongitudinal extensometers and the average transverse strain,t, indicated by the transverse extensometers, against theapplied force, P, as shown in Fig. 2. Determine the slopes,dl/dP, and dt/dP, of these lines. Ca

43、lculate Poissons ratiousing Eq 2. 5 dt/dP!/dl/dP! (2)8.2 The slopes may be determined graphically or numeri-cally.8.3 Graphical Method:8.3.1 The slopes may be determined by graphically drawinga straight line through each set of points.8.4 Numerical method:8.4.1 The slopes may be determined by linear

44、 regression ofaverage strain, , on applied force, P.NOTE 5For the method of least squares, random variations in the dataare considered as variations in strain. Readings at zero applied force andthe first small increment of force application are typically not included inthe calculations, and the line

45、 is not constrained to pass through zero dueto possible small offsets at zero applied force and small variations inestablishing the load path.8.4.2 The value of Poissons ratio obtained numericallyshould coincide with that obtained for a single large forceincrement between stresses below the proporti

46、onal limit.9. Report9.1 Report the following information:9.1.1 Specimen MaterialSpecimen material, alloy, heattreatment, mill batch number, grain direction, and other rel-evant material information.9.1.2 Specimen ConfigurationSketch of the specimenconfiguration or reference to the specimen drawing.9

47、.1.3 Specimen DimensionsActual measured dimensionsfor the specimen.9.1.4 Annealing procedureIf the specimen was subjectedto an annealing procedure to remove residual stress, include thedetails of this procedure.9.1.5 Test FixtureDescription of the test fixture or refer-ence to fixture drawings.9.1.6

48、 Testing Machine and ExtensometersManufacturer,model, serial number, and force range of the testing machineand the extensometers.9.1.7 Speed of TestingTest rate and mode of control.9.1.8 TemperatureTest temperature.9.1.9 Stress-Strain DiagramStress-strain diagram show-ing both longitudinal and trans

49、verse strain with scales, speci-men number, test data, rate, and other pertinent information.FIG. 2 Plot of Average Strains versus Applied Force for Determi-nation of Poissons RatioE132 1739.1.10 Poissons RatioValue and method to determine thevalue in accordance with Section 8.10. Precision and Bias10.1 Elastic properties such as Poissons ratio, shear modu-lus and Youngs modulus are not determined routinely and aregenerally not specified in materials specifications. Precisionand bias