ASTM E1876 : 22

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.

1.5 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 StandardDetails, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.