VELOCITY OF LONGITUDINAL VIBRATION IN SOLID RODS (ULTRASONIC METHOD) WITH SPECIAL REFERENCE TO THE ELASTICITY OF ICE

Abstract

An experimental research showing how corrections in the value of velocity of phase propagation may be made to take into account lateral inertia, and how the law (Rayleigh's) will break down at higher frequencies because of other types of vibration intervening. When the ratio of radius to length, multiplied by the mode of vibration [Formula: see text] exceeds a certain figure (in the case of duralumin, 0.55) the law breaks down, and it appears that radial longitudinal vibrations intervene. From the research a simple method emerges to determine Poisson's ratio, which in the case of duralumin is found to be 0.35.An application of this ultrasonic method is made to determine Young's modulus for ice, in order to find more consistent values than those generally quoted. The value of this modulus for ice at about 0 °C. is found to be about 9 × 1010 dynes/cm2. corresponding to a velocity of sound in it of 3.15 × 105 cm. per sec.