Clarification of the mechanism of fatigue strength improvement by material surface modification based on finite element modeling

基于有限元模型，研究了喷丸技术用于航空零部件等金属材料的轻量化和强度增强提高疲劳强度的机理。特别是针对高速水射流中气泡破裂产生的局部高冲击力空化喷丸，阐明了空化喷丸后材料表面力学性能(残余应力、屈服应力)与疲劳性能的关系。由于晶界对多晶金属的塑性性能有很大的影响，本文还通过晶体塑性分析，阐明了晶界等微观因素对喷丸后表面力学性能的影响。

The present study investigated the mechanism of fatigue strength improvement by peening technology used for weight reduction and strength enhancement of metallic materials, such as the materials for aeronautic components, based on finite element modeling. Especially, focusing on the cavitation peening (CP) using locally high impact force generated by the bubble collapsing in a high-speed water-jet, the relationship between the mechanical properties (residual stress, yield stress) evaluated on the surface of the material after CP and its fatigue properties was clarified. Since the grain boundary much affects the plastic properties of polycrystalline metals, the effect of the microscopic factors including grain boundary on the surface mechanical properties after peening were also clarified using crystal-plasticity analyses.