Residual stress relief through vibrations

Includes bibliographical references (pages 45-47)Since the discovery of the existence of residual stresses and of the harm they can produce, research for an easier process to relieve them has continued. Thermal relaxation has been the accepted method for many years. However, in the last decade a new process has been introduced commercially. This process utilizes induced vibrations for the relief of residual stresses. Since this process has appeared, there has been little research to substantiate the claims of the manufacturers. The research in this paper is designed to broaden the knowledge in this area. Two sample configurations were designed and tested experimentally to evaluate stress relief through vibration. Of the samples tested, there was no appreciable reduction in residual stresses. Two of the samples tested failed, and this was attributed to fatigue damage resulting from the induced vibrations. It was concluded that residual stress leveling was produced by the induced vibrations. This leveling effect was attributed to the plastic deformation of the material. If the material is plastically deformed in a cyclic manner, however, there is strong possibility of fatigue, damage, or reduction in fatigue life. Therefore, due to the possible fatigue damage encountered during the process of induced vibrations, it is recommended that this type of stress relief be used cautiously, especially in dynamic applications