Finite Element Analysis of Re-Cold Expansion in Order to Improve the Fatigue Life of Fastener Hole that has been Cold Expanded Before

Cold expansion of fastener holes has been successfully used for many years to impart beneficial compressive residual stresses. Beneficial compressive residual stress of fastener hole that has been cold expanded before is reduced by using of materials for a long time. As a result, fatigue life of material is reduced. So, compressive residual stresses of material have to regenerate by re-cold expansion method. In this paper, it was carried out a finite element analysis about variation of residual stress due to tensile stress and residual stress distribution that was regenerated by re-cold expansion method in the fastener hole. Here, a diversity tensile stress was used. Also, it was performed a finite element analysis according to cold expansion rate of re cold expansion in order to obtain a beneficial compressive residual stress.