Propagation of stress waves in rubber rods

Abstract

The propagation of longitudinal, torsional, and flexural waves in rubber rods was studied by a moving probe method. Conditions and materials were used for which the attenuation was sufficient to eliminate standing waves. Velocity and attenuation data were obtained for the different wave types over the frequency range 1 to 8 kc. at or near room temperature for different rubbers of accurately specified compositions. Complex Young's moduli were computed from both the longitudinal and flexural propagation data and found to be in good agreement with each other for the same rods under the same conditions. Complex shear moduli were computed from the torsional data. Ratios of the respective real parts and loss tangents of the Young's and shear moduli showed good agreement with theory but some dependence on material. Measurements were also made of the complex bulk moduli of materials identical to those studied in rod form.