Sonic Analysis of Fracture

Abstract

The passage of stress waves of large amplitude through solid specimens often produces fractures which differ in several respects from those which can occur under any other conditions. Many of the observed phenomena can be accounted for in terms of the acoustical treatment of reflection and refraction of stress waves at the boundaries of the specimen and of diffraction effects in regions where the dimensions of the specimen become comparable with the wavelength of the disturbance. When a fracture occurs it results in a sudden release of stress, and consequently, secondary stress waves travel out from the fracture surfaces. The experimental investigation of these effects by means of high-speed photography, by electrical measurements of stress and strain, and by subsequent examination of the geometry and appearance of the fractured surfaces will be described, and the type of information which such investigations may give about the nature of the phenomenon of brittle fracture will be discussed.