1.1 本试验方法测量材料的振动阻尼特性:损耗因子η和杨氏模量， E ，或剪切模量， G . 该方法在50至5000 Hz的频率范围和材料的有效温度范围内准确，适用于测试在结构振动、建筑声学和可闻噪声控制中应用的材料。此类材料包括金属、搪瓷、陶瓷、橡胶、塑料、增强环氧树脂基体和可形成悬臂梁试样结构的木材。 1.2 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。 1.3 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 阻尼材料的材料损耗系数和模量在设计措施以控制结构中的振动和这些结构辐射的声音，特别是共振时，非常有用。该试验方法通过使用阻尼悬臂梁理论进行间接测量来确定阻尼材料的特性。通过应用梁理论，合成的阻尼材料特性与用于获得它们的试样的几何形状无关。然后，可以将这些阻尼材料特性与数学模型一起用于设计阻尼系统，并在硬件制造之前预测其性能。这些模型包括简单的梁和板模拟以及有限元分析模型。 5.2 当用于测试由一个均质层组成的材料时，发现该试验方法产生了良好的结果。在某些阻尼应用中，阻尼设计可能由两个或更多具有显著不同特性的层组成。 如果要使数学模型的预测具有尽可能高的精度，这些复杂的设计必须对其组成层进行单独测试。 5.3 假设: 5.3.1 所有阻尼测量均在线性范围内进行，即阻尼材料的行为符合线性粘弹性理论。如果施加的力激励梁超出线性区域，则数据分析将不适用。对于线性梁行为，组合梁相对于静止的峰值位移应小于基础梁的厚度（见附录 X2.3 ). 5.3.2 施加在励磁传感器上的力信号幅值随频率保持恒定。如果力幅值不能保持恒定，则梁的响应必须除以力幅值。然后，必须使用作为频率函数表示的响应力比（称为柔度或接受度）来评估阻尼。 5.3.3 试样2b和2c的数据简化( 图2 )使用梁的经典分析，但不包括涉及转动惯量或剪切变形的项的影响。分析确实假设平面截面保持平面；因此，必须注意不要使用阻尼材料厚度远大于（约四倍）金属梁厚度的试样。 5.3.4 用于计算剪切阻尼材料特性的方程（夹层试样2d-见 图2 )不包括阻尼层的扩展术语。当阻尼层的模量远低于金属的模量（约十倍）时，这是一个可接受的假设。 5.3.5 计算夹层梁试验阻尼特性的方程（样本2d–见 图2 )使用正弦展开法对振动的振型进行了推导和求解。 对于夹层组合梁，这种近似仅在较高的模态下才可接受，并且忽略第一模态结果已成为惯例。对于其他样本配置（样本2a、2b和2c），可以使用第一模式结果。 5.3.6 假设金属梁的损耗因子（η）为零。 注1: 这是一个有充分根据的假设，因为钢和铝材料的损耗系数约为0.001或更小，显著低于组合梁的损耗系数。 5.4 注意事项: 5.4.1 除均匀试样外，梁测试技术基于阻尼（复合）梁和无阻尼（基础）梁之间的测量差异。当涉及大数值的微小差异时，用于计算材料特性的方程是病态的，并且具有较高的误差放大系数，即较小的测量误差会导致计算特性的较大误差。 为防止此类情况发生，建议: 5.4.1.1 对于安装在基础梁一侧的试样（参见 10.2.2 和 图2 b） ，术语( f c /f n ) 2. (1 + DT )应等于或大于1.01。 5.4.1.2 对于安装在基础梁两侧的试样（参见 10.2.3 和 图2 c） ，术语( f m /f n ) 2. (1 + 2 DT )应等于或大于1.01。 5.4.1.3 对于三明治样本（参见 10.2.4 和 图2 d） ，术语( f s /f n ) 2. (2 + DT )应等于或大于2.01。 5.4.1.4 上述限值为近似值。它们取决于阻尼材料相对于基础梁的厚度和基础梁的模量。然而，当条款在章节中的价值 5.4.1.1 , 5.4.1.2 或 5.4.1.3 接近这些极限时，应仔细评估结果。分段比率 5.4.1.1 , 5.4.1.2 和 5.4.1.3 应用于判断出错的可能性。 5.4.2 试样 图2 b和 图2 c通常用于杨氏模量大于100 MPa的硬质材料，在此类材料的玻璃态和过渡区测量性能。这些材料通常是自由层处理类型，例如搪瓷和负载乙烯基。夹层梁技术通常用于剪切模量小于100 MPa的软粘弹性材料。给出100 MPa的值，作为下列范围内基础梁厚度的指南: 8.4 . 较厚梁的值较高，较薄梁的值较低。当特定试样超过100 MPa准则时，试验数据可能看起来良好，减少的数据可能分散性很小，并且可能看起来是自一致的。虽然复合梁试验数据在此模量范围内是准确的，但计算的材料特性通常是错误的。 只有使用适合模量结果范围的试样配置，才能获得准确的材料性能结果。 5.4.3 在金属梁上应用有效阻尼材料通常会导致良好的阻尼响应和不太高的信噪比。因此，重要的是选择适当的阻尼材料厚度，以获得可测量的阻尼量。从试样的阻尼材料与金属梁的厚度比为1:1开始 图2 b和 图2 c和阻尼材料与其中一个夹层梁的厚度比为1:10( 图2 d） 。相反，应避免系统中的极低阻尼，因为阻尼和无阻尼系统之间的差异将很小。如果不能轻易改变阻尼材料的厚度以获得上述厚度比，请考虑改变基础梁的厚度（参见 8.4 ). 5.4.4 阅读并遵循所有材料应用说明。在适用的情况下，留出足够的时间来固化阻尼材料和用于将材料粘合到基础梁上的任何粘合剂。 5.4.5 了解用于将阻尼材料粘合到基础梁的任何粘合剂的特性。粘合剂的刚度及其应用厚度可能会影响复合梁的阻尼，并成为误差来源（参见 8.3 ). 5.4.6 在保存样品进行老化试验之前，考虑阻尼和粘合材料的已知老化极限。

1.1 This test method measures the vibration-damping properties of materials: the loss factor, η, and Young's modulus, E , or the shear modulus, G . Accurate over a frequency range of 50 to 5000 Hz and over the useful temperature range of the material, this method is useful in testing materials that have application in structural vibration, building acoustics, and the control of audible noise. Such materials include metals, enamels, ceramics, rubbers, plastics, reinforced epoxy matrices, and woods that can be formed to cantilever beam test specimen configurations. 1.2 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. 1.3 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 The material loss factor and modulus of damping materials are useful in designing measures to control vibration in structures and the sound that is radiated by those structures, especially at resonance. This test method determines the properties of a damping material by indirect measurement using damped cantilever beam theory. By applying beam theory, the resultant damping material properties are made independent of the geometry of the test specimen used to obtain them. These damping material properties can then be used with mathematical models to design damping systems and predict their performance prior to hardware fabrication. These models include simple beam and plate analogies as well as finite element analysis models. 5.2 This test method has been found to produce good results when used for testing materials consisting of one homogeneous layer. In some damping applications, a damping design may consist of two or more layers with significantly different characteristics. These complicated designs must have their constituent layers tested separately if the predictions of the mathematical models are to have the highest possible accuracy. 5.3 Assumptions: 5.3.1 All damping measurements are made in the linear range, that is, the damping materials behave in accordance with linear viscoelastic theory. If the applied force excites the beam beyond the linear region, the data analysis will not be applicable. For linear beam behavior, the peak displacement from rest for a composite beam should be less than the thickness of the base beam (See Appendix X2.3 ). 5.3.2 The amplitude of the force signal applied to the excitation transducer is maintained constant with frequency. If the force amplitude cannot be kept constant, then the response of the beam must be divided by the force amplitude. The ratio of response to force (referred to as the compliance or receptance) presented as a function of frequency must then be used for evaluating the damping. 5.3.3 Data reduction for both test specimens 2b and 2c ( Fig. 2 ) uses the classical analysis for beams but does not include the effects of the terms involving rotary inertia or shear deformation. The analysis does assume that plane sections remain plane; therefore, care must be taken not to use specimens with a damping material thickness that is much greater (about four times) than that of the metal beam. 5.3.4 The equations presented for computing the properties of damping materials in shear (sandwich specimen 2d - see Fig. 2 ) do not include the extensional terms for the damping layer. This is an acceptable assumption when the modulus of the damping layer is considerably (about ten times) lower than that of the metal. 5.3.5 The equations for computing the damping properties from sandwich beam tests (specimen 2d–see Fig. 2 ) were developed and solved using sinusoidal expansion for the mode shapes of vibration. For sandwich composite beams, this approximation is acceptable only at the higher modes, and it has been the practice to ignore the first mode results. For the other specimen configurations (specimens 2a, 2b, and 2c) the first mode results may be used. 5.3.6 Assume the loss factor (η) of the metal beam to be zero. Note 1: This is a well-founded assumption since steel and aluminum materials have loss factors of approximately 0.001 or less, which is significantly lower than those of the composite beams. 5.4 Precautions: 5.4.1 With the exception of the uniform test specimen, the beam test technique is based on the measured differences between the damped (composite) and undamped (base) beams. When small differences of large numbers are involved, the equations for calculating the material properties are ill-conditioned and have a high error magnification factor, i.e. small measurement errors result in large errors in the calculated properties. To prevent such conditions from occurring, it is recommended that: 5.4.1.1 For a specimen mounted on one side of a base beam (see 10.2.2 and Fig. 2 b), the term ( f c /f n ) 2 (1 + DT ) should be equal to or greater than 1.01. 5.4.1.2 For a specimen mounted on two sides of a base beam (see 10.2.3 and Fig. 2 c), the term ( f m /f n ) 2 (1 + 2 DT ) should be equal to or greater than 1.01. 5.4.1.3 For a sandwich specimen (see 10.2.4 and Fig. 2 d), the term ( f s /f n ) 2 (2 + DT ) should be equal to or greater than 2.01. 5.4.1.4 The above limits are approximate. They depend on the thickness of the damping material relative to the base beam and on the modulus of the base beam. However, when the value of the terms in Sections 5.4.1.1 , 5.4.1.2 , or 5.4.1.3 are near these limits the results should be evaluated carefully. The ratios in Sections 5.4.1.1 , 5.4.1.2 , and 5.4.1.3 should be used to judge the likelihood of error. 5.4.2 Test specimens Fig. 2 b and Fig. 2 c are usually used for stiff materials with Young's modulus greater than 100 MPa, where the properties are measured in the glassy and transition regions of such materials. These materials usually are of the free-layer type of treatment, such as enamels and loaded vinyls. The sandwich beam technique usually is used for soft viscoelastic materials with shear moduli less than 100 MPa. The value of 100 MPa is given as a guide for base beam thicknesses within the range listed in 8.4 . The value will be higher for thicker beams and lower for thinner beams. When the 100 MPa guideline has been exceeded for a specific test specimen, the test data may appear to be good, the reduced data may have little scatter and may appear to be self-consistent. Although the composite beam test data are accurate in this modulus range, the calculated material properties are generally wrong. Accurate material property results can only be obtained by using the test specimen configuration that is appropriate for the range of the modulus results. 5.4.3 Applying an effective damping material on a metal beam usually results in a well-damped response and a signal-to-noise ratio that is not very high. Therefore, it is important to select an appropriate thickness of damping material to obtain measurable amounts of damping. Start with a 1:1 thickness ratio of the damping material to the metal beam for test specimens Fig. 2 b and Fig. 2 c and a 1:10 thickness ratio of the damping material to one of the sandwich beams ( Fig. 2 d). Conversely, extremely low damping in the system should be avoided because the differences between the damped and undamped system will be small. If the thickness of the damping material cannot easily be changed to obtain the thickness ratios mentioned above, consider changing the thickness of the base beam (see 8.4 ). 5.4.4 Read and follow all material application directions. When applicable, allow sufficient time for curing of both the damping material and any adhesive used to bond the material to the base beam. 5.4.5 Learn about the characteristics of any adhesive used to bond the damping material to the base beam. The adhesive's stiffness and its application thickness can affect the damping of the composite beam and be a source of error (see 8.3 ). 5.4.6 Consider known aging limits on both the damping and adhesive materials before preserving samples for aging tests.