Production of Accelerated Cavitation Damage by an Acoustic Field in a Cylindrical Cavity

Abstract

A convenient and economical method for the production of cavitation damage is described. Cavitation is generated in the region of the maximum pressure amplitude of an acoustic field in a resonant cylindrical container. The specimen surface to be damaged is a stationary boundary in the system and is therefore not subject to accelerations such as occur in conventional magnetostriction devices for cavitation damage study. The absence of these accelerations eliminates any possibility of premature material removal from cavitation weakened surfaces. Mathematical analysis of the dynamics of cavitation should also be facilitated. It is shown that simple assumptions lead to an acoustical theory agreeing with experiment to within the accuracy required. Examples are given of the application of this technique to the study of both easily damaged and highly resistant materials. Relatively uniform damage is achieved which is particularly suitable for x‐ray diffraction study of the surface. Alternatively, perturbation of the acoustic field to permit concentrated damage is obtained by forming the specimen surface as the end of a small cylinder. Photomicrographic studies of damage to both monocrystalline and polycrystalline materials have been initiated with the aid of this apparatus. Cavitation experiments have been done in water with an air atmosphere and in toluene with a helium atmosphere. These experiments show that severe damage can result even if a chemically inert environment is employed.