Technique for Measuring the Dynamic Young's Modulus and Loss Factor.

As a part of an extensive program for measuring acoustical properties of polymeric materials, equipment has been designed and set up to measure the dynamic Youngs modulus of stiff materials with low acoustic dissipation. Both the elastic modulus and the loss factor are obtained. The method described is based on the excitation of longitudinal resonances in a suspended uniform thin rod having free-free end conditions. For samples of actual material, the results must be corrected for the effect of the radial inertia of the bar and the effects of the measurement equipment on the results. The properties of very lossy or limp materials are measured more conveniently by other techniques. Author-PL