Effect of Confinement Layer on Laser Ablation and Cavitation Bubble during Laser Shock Peening
Effect of Confinement Layer on Laser Ablation and Cavitation Bubble during Laser Shock Peening
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DOI：
10.2320/matertrans.m2016150
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发表时间：
2016-10
影响因子：
1.2
通讯作者：
T. Takata;M. Enoki;P. Chivavibul;A. Matsui;Yuji Kobayashi
中科院分区：
文献类型：
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作者：
T. Takata;M. Enoki;P. Chivavibul;A. Matsui;Yuji Kobayashi
激光冲击强化（Laser Shock Peening，LSP）是一种通过在金属表面附近产生残余压应力来提高材料抗疲劳、应力腐蚀等表面失效能力的表面处理方法。在LSP工艺中，短脉冲激光被聚焦并照射到被透明覆盖层覆盖的材料，例如玻璃或水。这种透明覆盖层也被称为限制层，并且在LSP工艺期间具有增加冲击压力的重要作用。当约束层为液体时，该层的特性（例如温度、粘度等）影响在喷丸过程期间发生的现象，并且无疑影响诱导的残余应力。本文采用声发射技术结合高速摄影技术研究了约束层对激光冲击强化过程的影响。通过对声发射波形和高速摄影气泡参数的反分析计算出冲击力，并对结果进行了讨论。结果表明，约束层的温度、厚度和粘度对空化泡的产生和溃灭有重要影响。利用声发射技术可以优化工艺参数。
Laser shock peening (LSP) is one of surface treatments to induce residual compressive stresses near metal surface to improve the resis- tance of materials to surface-related failures, such as fatigue and stress corrosion cracking. In LSP process, short pulsed laser is focused and irradiated to the material covered by transparent overlay such as glass or water. This transparent overlay is also known as a confinement layer and has an important role to increase impact pressure during LSP process. When confinement layer is liquid, the characteristics of the layer such as temperature, viscosity, etc. affect the phenomena occurring during the peening process and undoubtedly influence the induced residual stress. In the present study, Acoustic Emission (AE) technique coupling with high speed camera was applied to study the effect of confinement layer on LSP process. The results were discussed using the impact force calculated by inverse analysis of detected AE waveforms and bubble param- eters observed by high speed camera. The results showed that temperature, thickness and viscosity of confinement layer had strong influence on the generation and collapse of cavitation bubble. The optimization of process parameters could be obtained by AE technique.