Sound Velocity Measurements

Abstract

A method for measuring the modu lus of elasticity of fibers and films by sonic means is described, and the results of an exploratory study of this modulus in various nat ural and synthetic fib ers and films are given. The method is based on the equation for the prop agation of longitudinal (sound) waves in elastic materials, which expresses the velocity of propa gation in terms of the elastic modulus and density of the me dium. The procedure involves measuring the sound velocity and calculating the modulus, using the proper density value. The modu lus so calculated is characteristic of a dynamic, essentially adiabatic, high-loading rate, short period measurement, since a sound fre quency of approximately 10,000 cycles per second was used. The range of moduli for common textile materials was from 1 X 10¹⁰ to 50 X 10¹⁰ dynes per square centi meter.