ASTM C1548

ASTM C1548 – Standard Test Method for Dynamic Young’s Modulus, Shear Modulus, and Poisson’s Ratio of Refractory Materials by Impulse Excitation of Vibration

Description:

Significance and Use

4.1 This test method is nondestructive and is commonly used for material characterization and development, design data generation, and quality control purposes. The test assumes that the properties of the specimen are perfectly isotropic, which may not be true for some refractory materials. The test also assumes that the specimen is homogeneous and elastic. Specimens that are micro-cracked are difficult to test since they do not yield consistent results. Specimens with low densities have a damping effect and are easily damaged locally at the impact point. Insulating bricks can generally be tested with this technique, but fibrous insulating materials are generally too weak and soft to test.

4.2 For quality control use, the test method may be used for measuring only resonant frequencies of any standard size specimen. An elastic modulus calculation may not be needed or even feasible if the shape is nonstandard, such as a slide gate plate containing a hole. Since specimens will vary in both size and mass, acceptable frequencies for each shape and material must be established from statistical data.

4.3 Dimensional variations can have a significant effect on modulus values calculated from the frequency measurements. Surface grinding may be required to bring some materials into the specified tolerance range.

4.4 Since cylindrical shapes are not commonly made from refractory materials they are not covered by this test method, but are covered in Test Method C215.

Scope

1.1 This test method covers the measurement of the fundamental resonant frequencies for the purpose of calculating the dynamic Young’s modulus, the dynamic shear modulus (also known as the modulus of rigidity), and the dynamic Poisson’s ratio of refractory materials at ambient temperatures. Specimens of these materials possess specific mechanical resonant frequencies, which are determined by the elastic modulus, mass, and geometry of the test specimen. Therefore, the dynamic elastic properties can be computed if the geometry, mass, and mechanical resonant frequencies of a suitable specimen can be measured. The dynamic Young’s modulus is determined using the resonant frequency in the flexural mode of vibration and the dynamic shear modulus is determined using the resonant frequency in the torsional mode of vibration. Poisson’s ratio is computed from the dynamic Young’s modulus and the dynamic shear modulus.

1.2 Although not specifically described herein, this method can also be performed at high temperatures with suitable equipment modifications and appropriate modifications to the calculations to compensate for thermal expansion.

1.3 The values are stated in SI units and are to be regarded as the standard.