Research status and tendency on cold expansion anti-fatigue manufacturing technology for aircraft structural fastening holes

Abstract

Cold expansion technology is extensively exploited in the strengthening of fastening holes in aircraft structures due to its exceptional efficiency and stability. The fatigue performance of perforated parts can be effectively improved without compromising the structural integrity, thus satisfying the durability design requirements of the modern aviation manufacturing industry. In recent years, the cold expansion strengthening technology has gradually matured. This present article provides a comprehensive review of the cold expansion strengthening mechanism, commonly employed methods for reinforcement, and fatigue gain control applied to fastening holes in aircraft structures. The basic principles of the cold expansion anti-fatigue manufacturing process are introduced, while also elaborating on the optimization of typical expansion process methods and their anti-fatigue effects, as well as discussing the factors contributing to any observed differences. Subsequently, the research progress and academic achievements are concluded, in terms of methodological enhancements, distributions of residual stress fields, investigations into microscopic deformation behavior and improvements in fatigue performance gain. In addition, the critical factors influencing the anti-fatigue performance are comprehensively discussed. Finally, the future development trend of cold expansion strengthening technology for fastener holes is highlighted, taking into account the existing limitations and challenges in current research.