Measurement Methods for Materials Properties: Elasticity

Published

February 19, 2017

Author(s)

Sheldon M. Wiederhorn, Richard J. Fields

Abstract

Elastic constants must be obtained by experiment methods. Materials are too complicated and theory of solids insufficiently sophisticated to obtain accurate theoretic determinations of elastic constants. Usually, simple static mechanical tests are used to evaluate the elastic constants. Specimens are either pulled in tension, squeezed in compression, bent in flexure or twisted in torsion and the strains measured by a variety of techniques. The elastic constants are then calculated from the elasticity equation relating stress to strain. From these measurements, Young s Modulus, Poisson s Ratio and the Shear Modulus are determined. These are the moduli commonly used for the calculation of stresses or strains in structural applications. More accurate than the static method of determining the elastic constants are the dynamic techniques that have been developed for this purpose. In these techniques a bar is set into vibration and the resonant frequencies of the bar are measured. A solution of the elastic equations for the vibration of a bar yields a relationship between the elastic constants, the resonant frequencies and the dimensions of the bar. These techniques are about five times as accurate as the static techniques of determining the elastic constants. Elastic constants can also be measured by determining the time of flight of an elastic wave through a plate of given thickness. Because there are two kinds of waves that can traverse the plate (longitudinal waves and shear waves), the two elastic constants required for structural calculations can be determined independently. Finally, the newest advances in techniques for measuring the elastic constants of materials have their origins in the need to measure these constants in thin films, or parts too small to be determined i

Citation

Measurement Methods for Materials Properties: Elasticity

Publisher Info

Handbook of Measurement Methods Springer-Verlag,

Pub Type

Books

Keywords

elastic modulus, elasticity, Poisson's ratio, shear modulus, Young's modulus

Citation

Wiederhorn, S. and Fields, R. (2017), Measurement Methods for Materials Properties: Elasticity, Handbook of Measurement Methods Springer-Verlag, (Accessed April 18, 2024)