1.1 本试验方法包括在环境温度下测定弹性材料的动态弹性特性。这些材料的试样具有特定的机械共振频率，该频率由试样的弹性模量、质量和几何形状决定。因此，如果可以测量材料的适当（矩形或圆柱形）试样的几何形状、质量和机械共振频率，则可以计算材料的动态弹性特性。使用弯曲或纵向振动模式中的共振频率确定动态杨氏模量。动态剪切模量或刚度模量是通过扭转共振找到的。动态杨氏模量和动态剪切模量用于计算泊松比。 1.2 计算适用于弹性、均匀和各向同性材料。各向异性会增加额外的计算误差。看见 附录X1 详细信息。 1.3 混合数值实验技术（MNET）的使用不在本标准的范围内。 1.4 该试验方法可用于测定复合材料（颗粒、晶须或纤维增强）或其他各向异性材料的动态杨氏模量，只有在考虑了试样中增强的影响后。可能影响测得动态杨氏模量的钢筋特性示例包括体积分数、尺寸、形态、分布、方向、弹性特性和界面粘结。 1.4.1 在解释此类材料的试验结果时，应考虑钢筋特性的影响。 注1: 钢筋的性能将直接影响测得的弹性性能。数据如所示 ( 1. ) 2. 表明由于各向异性，动态杨氏模量可能低估20% 1.5 本试验方法不应用于确定具有裂纹、孔隙或其他主要结构不连续性的试样的准确动态杨氏模量、动态剪切模量或泊松比。 1.6 该试验方法可用于通过将结果与无缺陷试样进行比较来确定试样中是否存在结构不连续性。 1.7 本试验方法不得用于确定无法在均匀矩形或圆柱形横截面中制造的材料的准确动态杨氏模量、动态剪切模量或泊松比。 1.8 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.9 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。 1.10 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====== 5.1 该试验方法可用于材料开发、表征、设计数据生成和质量控制目的。 5.2 本试验方法特别适用于测定弹性、均匀和各向同性材料的动态弹性模量 ( 3. ) . 5.3 本试验方法涉及在室温下测定细长杆（矩形截面）杆（圆柱形）和扁平圆盘的动态弹性模量。也可以类似地测量平板，但没有给出确定模量所需的方程。 5.4 这种动态测试方法与静态加载技术和需要连续激励的共振技术有几个优点和区别。 5.4.1 该试验方法本质上是无损的，可用于为其他试验准备的试样。试样承受微小应变；因此，在应力-应变曲线原点处或附近测量模量，断裂可能性最小。 5.4.2 冲击激励试验使用冲击工具和试样的简单支架。不需要复杂的支持系统，需要精心设置或对齐。 5.5 该技术可单独用于测量谐振频率，用于质量控制和验收规则形状和复杂形状的试样。确定具有特定几何形状和质量的试样的可接受共振频率范围。该技术特别适用于具有复杂几何形状（平行六面体、圆柱体/杆或圆盘除外）的试样，这些几何形状不适合通过其他程序进行测试。任何频率响应超出规定频率范围的样本均被拒收。 只要已知选定频率范围的极限包括试样必须具有的共振频率（如果其几何形状和质量在规定公差范围内），则无需确定每个试样的实际动态弹性模量。 5.6 如果热处理或环境暴露影响试样的弹性响应，则本试验方法可能适用于测定热历史、环境暴露等的特定影响。样本描述应包括样本接受的任何特定热处理或环境暴露。

1.1 This test method covers determination of the dynamic elastic properties of elastic materials at ambient temperatures. Specimens of these materials possess specific mechanical resonant frequencies that are determined by the elastic modulus, mass, and geometry of the test specimen. The dynamic elastic properties of a material can therefore be computed if the geometry, mass, and mechanical resonant frequencies of a suitable (rectangular or cylindrical geometry) test specimen of that material can be measured. Dynamic Young's modulus is determined using the resonant frequency in either the flexural or longitudinal mode of vibration. The dynamic shear modulus, or modulus of rigidity, is found using torsional resonant vibrations. Dynamic Young's modulus and dynamic shear modulus are used to compute Poisson's ratio. 1.2 Calculations are valid for materials that are elastic, homogeneous, and isotropic. Anisotropy can add additional calculation errors. See Appendix X1 for details. 1.3 The use of mixed numerical-experimental techniques (MNET) is outside the scope of this standard. 1.4 This test method may be used for determining dynamic Young’s modulus for materials of a composite character (particulate, whisker or fiber reinforced) or other anisotropic materials only after the effect of the reinforcement in the test specimen has been considered. Examples of the characteristics of the reinforcement that can affect the measured dynamic Young’s modulus are volume fraction, size, morphology, distribution, orientation, elastic properties, and interfacial bonding. 1.4.1 The effect of the character of the reinforcement shall be considered in interpreting the test results for these types of materials. Note 1: The properties of the reinforcement will directly affect measured elastic properties. Data shown in ( 1 ) 2 indicates the possibility of underestimating the dynamic Young’s modulus by as much as 20 % due to anisotropy 1.5 This test method should not be used for establishing accurate dynamic Young’s modulus, dynamic shear modulus, or Poisson’s ratio for specimens that have cracks, voids, or other major structural discontinuities. 1.6 This test method may be used for determining whether structural discontinuities exist in a specimen by comparing results with a specimen that is defect free. 1.7 This test method shall not be used for establishing accurate dynamic Young’s modulus, dynamic shear modulus or Poisson’s ratio for materials that cannot be fabricated in uniform rectangular or cylindrical cross section. 1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.9 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. 1.10 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 ====== 5.1 This test method may be used for material development, characterization, design data generation, and quality control purposes. 5.2 This test method is specifically appropriate for determining the dynamic elastic modulus of materials that are elastic, homogeneous, and isotropic ( 3 ) . 5.3 This test method addresses the room temperature determination of dynamic elastic moduli of elasticity of slender bars (rectangular cross section) rods (cylindrical), and flat disks. Flat plates may also be measured similarly, but the required equations for determining the moduli are not presented. 5.4 This dynamic test method has several advantages and differences from static loading techniques and from resonant techniques requiring continuous excitation. 5.4.1 The test method is nondestructive in nature and can be used for specimens prepared for other tests. The specimens are subjected to minute strains; hence, the moduli are measured at or near the origin of the stress-strain curve, with the minimum possibility of fracture. 5.4.2 The impulse excitation test uses an impact tool and simple supports for the test specimen. There is no requirement for complex support systems that require elaborate setup or alignment. 5.5 This technique can be used to measure resonant frequencies alone for the purposes of quality control and acceptance of test specimens of both regular and complex shapes. A range of acceptable resonant frequencies is determined for a specimen with a particular geometry and mass. The technique is particularly suitable for testing specimens with complex geometries (other than parallelepipeds, cylinders/rods, or disks) that would not be suitable for testing by other procedures. Any specimen with a frequency response falling outside the prescribed frequency range is rejected. The actual dynamic elastic modulus of each specimen need not be determined as long as the limits of the selected frequency range are known to include the resonant frequency that the specimen must possess if its geometry and mass are within specified tolerances. 5.6 If a thermal treatment or an environmental exposure affects the elastic response of the test specimen, this test method may be suitable for the determination of specific effects of thermal history, environment exposure, and so forth. Specimen descriptions should include any specific thermal treatments or environmental exposures that the specimens have received.