1.1 本试验方法涵盖在室温下通过结构材料的拉伸试验确定泊松比。本试验方法仅限于矩形截面的试样，以及与加载时立即产生的应变相比，蠕变可以忽略不计的材料和应力。 1.2 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 当向实体施加单轴力时，它会在所施加力的方向上变形，但也会根据力是拉伸力还是压缩力而横向膨胀或收缩。如果固体是均质和各向同性的，并且材料在外力作用下保持弹性，则横向应变与轴向应变具有恒定关系。该常数称为泊松比，与杨氏模量和剪切模量一样，是材料的固有特性。 4.2 泊松比用于结构设计，其中需要考虑因施力引起的所有尺寸变化，并用于将广义弹性理论应用于结构分析。 4.3 在本试验方法中，泊松比值仅由单轴应力产生的应变获得。 4.4 在比例极限以上，横向应变与轴向应变之比将取决于平均应力和测量的应力范围，因此不应视为泊松比。然而，如果报告该比值作为低于比例极限的应力的“泊松比”值，则应报告应力范围。 4.5 如果用下面描述的方法确定的泊松比μ与当泊松比 E/G 杨氏模量， E ，剪切模量， G ，代入以下等式: 哪里 E 和 G 必须以高于μ测量所需精度的精度进行测量。 4.6 泊松比测定的精度通常受到横向应变测量精度的限制，因为这些测量中的百分比误差通常大于轴向应变测量中的百分比误差。 由于测量的是比率而不是绝对量，因此只需要准确了解引伸计校准因子的相对值。此外，一般情况下，不需要准确知道施加力的值。在测定杨氏模量和比例极限的同时测定泊松比通常是有利的。

1.1 This test method covers the determination of Poisson’s ratio from tension tests of structural materials at room temperature. This test method is limited to specimens of rectangular section and to materials in which and stresses at which creep is negligible compared to the strain produced immediately upon loading. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 When uniaxial force is applied to a solid, it deforms in the direction of the applied force, but also expands or contracts laterally depending on whether the force is tensile or compressive. If the solid is homogeneous and isotropic, and the material remains elastic under the action of the applied force, the lateral strain bears a constant relationship to the axial strain. This constant, called Poisson’s ratio, is an intrinsic material property just like Young’s modulus and Shear modulus. 4.2 Poisson's ratio is used for design of structures where all dimensional changes resulting from application of force need to be taken into account, and in the application of the generalized theory of elasticity to structural analysis. 4.3 In this test method, the value of Poisson's ratio is obtained from strains resulting from uniaxial stress only. 4.4 Above the proportional limit, the ratio of transverse strain to axial strain will depend on the average stress and on the stress range for which it is measured and, hence, should not be regarded as Poisson’s ratio. If this ratio is reported, nevertheless, as a value of “Poisson’s ratio” for stresses below the proportional limit, the range of stress should be reported. 4.5 Deviations from isotropy should be suspected if the Poisson’s ratio, μ, determined by the method described below differs significantly from that determined when the ratio E/G of Young’s modulus, E , to shear modulus, G , is substituted in the following equation: where E and G must be measured with greater precision than the precision desired in the measurement of μ. 4.6 The accuracy of the determination of Poisson's ratio is usually limited by the accuracy of the transverse strain measurements because the percentage errors in these measurements are usually greater than in the axial strain measurements. Since a ratio rather than an absolute quantity is measured, it is only necessary to know accurately the relative value of the calibration factors of the extensometers. Also, in general, the values of the applied forces need not be accurately known. It is frequently expedient to make the determination of Poisson's ratio concurrently with determinations of Young's modulus and the proportional limit.