Using resonance to measure the independent elastic constants of problematic materials such as elastomers

The determination of the elastic constants for a solid material may be conveniently accomplished by measuring resonances corresponding to the elastic normal modes of a sample. Isotropic materials should be particularly straightforward, since they involve only two independent elastic constants, the shear modulus and the longitudinal modulus. In practice one typically measures the shear modulus and Young's modulus, but for some problematic materials these are not truly independent. Probing the microscopic processes of solid mechanical behavior requires knowledge of independent moduli. In this paper, a resonance method for directly measuring the independent moduli for problematic materials is described.