AE monitoring in water during laser shock peening process

Author:  T. Takata, M. Enoki, A. Matsui, Y. Kobayashi
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.238-243)
Doc ID:  2014082
Year of Publication:  2014
Abstract:  
Laser shock peening (LSP) is recognized as an efficient surface treatment to improve the fatigue life of metal components. To understand LSP process, acoustic emission (AE) method is expected to be useful for because an elastic wave generates when laser is irradiated on a target. In previous study, we were able to detect shock wave during LSP process by an AE sensor attached to a target and the results show that a cavitation bubble generates after laser irradiation and shock wave is also emitted by the bubble collapse, not only by laser ablation. However, AE wave propagated in a target is affected by the material and size and need to attach an AE sensor to a target directly. Therefore, AE wave propagated in a target has some disadvantage from point of view of AE monitoring. In this study, for easier AE monitoring, we detected AE wave propagated in water and compared that with AE waveforms propagated in a target. Impact forces during LSP process were obtained from detected AE waveforms by deconvolution technique. In addition, at the same time as AE measurement, we observed target surface by high speed camera and investigated phenomena during LSP process.