ASTM E132-2004 Standard Test Method for Poissons Ratio at Room Temperature《室温下泊松比率的标准试验方法》.pdf

1、Designation: E 132 04Standard Test Method forPoissons Ratio at Room Temperature1This standard is issued under the fixed designation E 132; 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 paren

2、theses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the determination of Poissonsratio from tens

3、ion 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 re

4、gardedas the 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

5、to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE 6 Terminology Relating to Methods of Mechanical Test-ingE8 Test Methods for Tension Testing of Metallic MaterialsE83 Practice for Verification and Classification of Exten-sometersE 111 Test Met

6、hod for Youngs Modulus, Tangent Modulus,and Chord ModulusE 1012 Practice for Verification of Specimen AlignmentUnder Tensile Loading3. Terminology3.1 Definitions:3.1.1 Poissons ratiothe negative of the ratio of trans-verse strain to the corresponding axial strain resulting from anaxial stress below

7、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, neverthe

8、less, 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 themeth

9、od 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: 5 E/2G! 2 1 (1)where E and G must be measured with greater precision thanthe precision desired in the measurement of .4. Significance

10、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

11、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 applica

12、tion 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 determina

13、tion 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. Sincea ratio rather than an absolute quantity is measured, it is onlynecessary to know accurat

14、ely the relative value of the calibra-tion factors of the extensometers.Also, in general, the values of1This 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 April 1, 2

15、004. Published April 2004. Originallyapproved in 1958. Last previous edition approved in 1997 as E 132 97.2For 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 standa

16、rds Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the applied forces need not be accurately known. It is fre-quently expedient to make the determination of Poissons ratioconcurrently with de

17、terminations of Youngs modulus and theproportional limit.6. Apparatus6.1 ForcesForces shall be applied either by verified deadweights or in a testing machine that has been calibrated inaccordance with Practices E4.6.2 ExtensometersClass B-1 extensometers or better, asdescribed in Practice E83, shall

18、 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 E83are used,it may be necessary to apply corrections, for example, the correction forthe transverse sens

19、itivity3of bonded resistance gages.6.2.1 It is recommended that at least two pairs of extensom-eters be usedone pair for measuring axial strain and the otherfor transverse strain, with the extensometers of each pairparallel to each other and on opposite sides of the specimen.Additional extensometers

20、 may be used to check on alignmentor to obtain better average strains in the case of unavoidablevariations in thickness. The extensometers should be placed onthe specimen with a free distance of at least one specimenwidth between any extensometer and the nearest fillet, and atleast two specimen widt

21、hs 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 extensometers, can be used if theconditions are very nearly ideal with respect to axial

22、ity 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 effect of a uniformvariation in thickness in the axial direction. The other arrangement of

23、 threepairs of extensometers, arrangement (c), provides a check on alignment.6.3 Alignment DevicesGrips and other devices for obtain-ing and maintaining axial alignment are shown in Test MethodsE8.7. Test Specimens7.1 Selection and Preparation of SpecimensSelect andprepare test specimens that are st

24、raight and uniform in thick-ness and representative of the material being tested.7.2 DimensionsThe recommended specimen configura-tion has a tested length of at least five times the tested width,and a length between the grips of at least seven times the testedwidth. The tested width itself is at lea

25、st equal to the testedthickness. The radius of the fillets of a standard rectangularspecimen is not less than the minimum width of the specimen.The width shall be constant over the entire length where theextensometers are placed and for an additional distance at eachend equal to at least this width,

26、 unless otherwise provided inthe product specifications.7.3 Stress ReliefThis test method is intended to produceintrinsic materials properties. Therefore, the specimen needs tobe free of residual stresses, which may require an annealingprocedure at Tm/3 for 30 min (Tmis the melting point of themater

27、ial in K). If the intent of the test is to verify theperformance of a product, the heat treatment procedure may beomitted. Record the condition of the material tested, includingany heat treatment, in the test report.8. Procedure8.1 Measurement of SpecimensAll surfaces on the rectan-gular specimen sh

28、all 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 0.001 in. (0.025 mm) and width shall bemeasured to within 0.0001 in. (0.0025 mm) at three locationsand an a

29、verage determined.NOTE 3For 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 accuracy.8.2 AlignmentProcedures for verifying the alignment aredescribed in detail in Practice E 1012. The al

30、lowable bendingas defined in Practice E 1012 shall not exceed 5 %.8.3 Record simultaneous measurements of applied force andstrain.8.4 Speed of TestingThe speed of testing shall be lowenough to make the thermal effects of adiabatic expansion orcontraction negligible, yet high enough to make creep neg

31、li-gible. In applying forces with dead weights, avoid temporaryoverloading due to inertia of the weights.8.5 Applied ForcesThe applied forces shall correspond tostresses that are within the linear portion of the stress-straincurve, that is, less than the proportional limit. The precision ofthe value

32、 of Poissons ratio obtained will depend on thenumber of data pair of longitudinal and transverse strain taken(see Fig. 2).8.6 Strain ReadingsRead all extensometers at the sameapplied force.8.7 TemperatureRecord the temperature. Avoid changesin temperature during the test.3Perry, C. C., and Lissner,

33、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 ExtensometersE1320429. Evaluation of Data9.1 Plot the average longitudinal str

34、ain, el, indicated by thelongitudinal extensometers and the average transverse strain,et, indicated by the transverse extensometers, against theapplied force, P, as shown in Fig. 2. Draw a straight linethrough each set of points, and determine the slopes, del/dP,and det/dP, of these lines. Calculate

35、 Poissons ratio as follows: 5 det/dP!/del/dP! (2)9.2 The errors introduced by drawing a straight line throughthe points can be reduced by applying the method of leastsquares.4,5, 6The value of Poissons ratio thus obtained shouldcoincide with that obtained for a single large force incrementbetween st

36、resses below the proportional limit.NOTE 4For the method of least squares, random variations in the dataare considered as variations in strain. In determining the stress range(force range) for which data should be used in the calculations, it is helpfulto examine the data using the strain deviation

37、method described in TestMethod E 111. Due to possible small offsets at zero applied force andsmall variations in establishing the load path in the specimen during thefirst small increment of force application, the readings at zero appliedforce and the first small increment of force application are t

38、ypically notincluded in the calculations, and the line is not constrained to pass throughzero.10. Report10.1 Report the following information:10.1.1 Specimen MaterialSpecimen material, alloy, heattreatment, mill batch number, grain direction, and other rel-evant material information.10.1.2 Specimen

39、ConfigurationSketch of the specimenconfiguration or reference to the specimen drawing.10.1.3 Specimen DimensionsActual measured dimen-sions for the specimen.10.1.4 Test FixtureDescription of the test fixture or refer-ence to fixture drawings.10.1.5 Testing Machine and ExtensometersManufacturer,model

40、, serial number, and force range of the testing machineand the extensometers.10.1.6 Speed of TestingTest rate and mode of control.10.1.7 TemperatureTest temperature.10.1.8 Stress-Strain DiagramStress-strain diagram show-ing both longitudinal and transverse strain with scales, speci-men number, test

41、data, rate, and other pertinent information.10.1.9 Poissons RatioValue and method to determine thevalue in accordance with Section 9.11. Precision and Bias11.1 Elastic properties such as Poissons ratio, shear modu-lus and Youngs modulus are not determined routinely and aregenerally not specified in

42、materials specifications. Precisionand bias statements for this test method are therefore notavailable.12. Keywords12.1 axial strain; longitudinal strain; Poissons ratio; stress-strain diagram; transverse strainASTM International takes no position respecting the validity of any patent rights asserte

43、d in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by th

44、e responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive

45、careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Internat

46、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through t

47、he ASTM website(www.astm.org).4Youden, W. J., Statistical Methods for Chemicals, John Wiley and Sons, Inc.,New York, NY, Chapter 5, 1951, pp. 4049.5Natrella, M. G., “Experimental Statistics,” National Bureau of StandardsHandbook 91, U.S. Dept. of Commerce, Chapter 5.6Bowker, A. H., and Lieberman, G. J., Engineering Statistics, Prentice-Hall,Inc., Englewood Cliffs, NJ, 1959, Chapter 9.FIG. 2 Plot of Average Strains versus Applied Force forDetermination of Poissons RatioE132043