Anisotropic elastic constants: Measurement by impact resonance

Modes of unrestrained free vibration of rectangular parallelepipeds are excited by impact and combined with solutions to the weak form of the equations of motion corresponding to the 3D equations of elasticity and periodic motion to provide estimates for the elastic constants of anisotropic materials. This method has been previously applied to isotropic materials based on analytic approximations for the relationship between elastic constants and resonant frequencies. The present approach extends this procedure to account for material anisotropy and variance in specimen dimension, and we apply this technique to several specimens of differing material type, constitution, and shape to compute various components of the elastic stiffness tensor. Our results are in very good agreement with those found by other techniques.