Abstract
Shot peening has been widely adopted as a fatigue life enhancement process, especially in the aerospace industry. High plastic deformation generated from high velocity shots impart a layer of compressive residual stresses up to sub-surface depth of about 100 microns. High surface waviness generated on the components' surface at the same time could lead to stress concentration and crack initiation, and hence an additional vibratory polishing step is needed as follow up process to reduce surface waviness caused by shot peening. This increase the process time and costs greatly despite the beneficial effect from fatigue life improvement. Vibropeening has been identified as an alternative surface treatment process which is able to induce comparable residual stress as shot peening, but with better surface finish as vibropolish in a single process. Recent studies showed that the concept of double vibratory process which incorporated an external vibration to the component on top of the vibration effect from machine, is able to reduce the process time even further to up to 50% to achieve desired outputs. In this paper, the author has investigated the effect of an additional external vibratory actuation at localized areas of the component in a vibropeening environment on Almen intensity, residual stresses and microstructure. The author also developed a smart vibropeening setup that is more suitable to the application in industrial production, enabling better process monitoring compared to conventional methods of RPM based control. The study showed that with vibratory actuation, an improvement in Almen intensity and residual stress was obtained, which could be potentially optimized further for uniform treatment of vibropeening with reduced process time. (c) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)