ASTM E143-2002(2008) 516 Standard Test Method for Shear Modulus at Room Temperature《室温下剪切模量的标准试验方法》.pdf
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1、Designation: E 143 02 (Reapproved 2008)Standard Test Method forShear Modulus at Room Temperature1This standard is issued under the fixed designation E 143; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、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 Department of Defense.1. Scope1.1 This test method covers the determination of shearmo
3、dulus of structural materials. This test method is limited tomaterials in which, and to stresses at which, creep is negligiblecompared to the strain produced immediately upon loading.Elastic properties such as shear modulus, Youngs modulus,and Poissons ratio are not determined routinely and aregener
4、ally not specified in materials specifications. Precisionand bias statements for these test methods are therefore notavailable.1.2 UnitsThe values stated in inch-pound units are to beregarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided forin
5、formation only and are not considered standard.1.3 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropr
6、iate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E6 Terminology Relating to Methods of Mechanical Test-ingE 8/E 8M Test Methods for Tension Testing of MetallicMaterialsE 111 Test Method forYoungs Modul
7、us, Tangent Modulus,and Chord ModulusE 1012 Practice for Verification of Test Frame and Speci-men Alignment Under Tensile and Compressive AxialForce Application3. Terminology3.1 Definitions:3.1.1 shear modulus FL2the ratio of shear stress tocorresponding shear strain below the proportional limit, al
8、socalled torsional modulus and modulus of rigidity. (See Fig. 1.)NOTE 1The value of shear modulus may depend on the direction inwhich it is measured if the material is not isotropic. Wood, many plasticsand certain metals are markedly anisotropic. Deviations from isotropyshould be suspected if the sh
9、ear modulus, G, differs from that determinedby substituting independently measured values of Youngs modulus, E,and Poissons ratio, in the relationG 5E21 1 !(1)NOTE 2In general, it is advisable, in reporting values of shearmodulus to state the stress range over which it is measured.3.1.2 torque, FLa
10、moment (of forces) that produces ortends to produce rotation or torsion.3.1.3 torsional stress FL2the shear stress in a body, ina plane normal to the axis or rotation, resulting from theapplication of torque.3.1.4 angle of twist (torsion test) the angle of relativerotation measured in a plane normal
11、 to the torsion specimenslongitudinal axis over the gage length.3.1.5 For definitions of other terms used in this test method,refer to Terminology E6.4. Summary of Test Method4.1 The cylindrical or tubular test specimen is loaded eitherincrementally or continuously by applying an external torqueso a
12、s to cause a uniform twist within the gage length.4.1.1 Changes in torque and the corresponding changes inangle of twist are determined either incrementally or continu-ously. The appropriate slope is then calculated from the shearstress-strain curve, which may be derived under conditions ofeither in
13、creasing or decreasing torque (increasing from pre-torque to maximum torque or decreasing from maximumtorque to pretorque).5. Significance and Use5.1 Shear modulus is a material property useful in calculat-ing compliance of structural materials in torsion provided theyfollow Hookes law, that is, the
14、 angle of twist is proportional tothe applied torque. Examples of the use of shear modulus arein the design of rotating shafts and helical compression springs.1This test method is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.0
15、4 onUniaxial Testing.Current edition approved May 1, 2008. Published December 2008. Originallyapproved in 1959. Last previous edition approved in 2002 as E 143 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
16、 of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 3For materials that follow nonlinear elastic stress-strain behav-ior, the valu
17、e of tangent or chord shear modulus is useful for estimatingthe change in torsional strain to corresponding stress for a specified stressor stress-range, respectively. Such determinations are, however, outsidethe scope of this standard. (See for example Ref (1).)35.2 The procedural steps and precisi
18、on of the apparatus andthe test specimens should be appropriate to the shape and thematerial type, since the method applies to a wide variety ofmaterials and sizes.5.3 Precise determination of shear modulus depends on thenumerous variables that may affect such determinations.5.3.1 These factors incl
19、ude characteristics of the specimensuch as residual stress, concentricity, wall thickness in the caseof tubes, deviation from nominal value, previous strain historyand specimen dimension.5.3.2 Testing conditions that influence the results include:axial position of the specimen, temperature and tempe
20、raturevariations, and maintenance of the apparatus.5.3.3 Interpretation of data also influences results.6. General Considerations6.1 Shear modulus for a specimen of circular cross-sectionis given by the equation4G 5 TL/Ju (2)where:G = shear modulus of the specimen,T = torque,L = gage length,J = pola
21、r moment of inertia of the section about its center,andu = angle of twist, in radians.6.1.1 For a solid cylinder:J 5pD4/32 (3)where:D = diameter.6.1.2 For a tube:J 5p32D042 Di4! (4)where:D0= outside diameter, andDi= inside diameter.7. Apparatus7.1 Testing MachineThe torsion testing machine, which is
22、to be used for applying the required torque to the specimen,shall be calibrated for the range of torques used in thedetermination. Corrections may be applied for demonstratedsystematic errors. The torques should be chosen such as tobring the error DG in shear modulus, due to errors in torqueDT, well
23、 within the required accuracy (see 12.3.1).7.2 GripsThe ends of the specimen shall be grippedfirmly between the jaws of a testing machine which have beendesigned to produce a state of uniform twist within the gagelength. In the case of tubes, closely fitting rigid plugs, such asare shown in Fig. 11
24、(Metal Plugs for Testing TubularSpecimens) of Test Methods E 8/E 8M may be inserted in theends to permit tightening the grips without crushing thespecimen. The grips shall be such that axial alignment can beobtained and maintained in order to prevent the application ofbending moments. One grip shall
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