Finite Element Simulation of the Cold Expansion Process with Split Sleeve in 7075 Aluminum Alloy

The cold expansion process of split sleeve produces residual compressive stress around the hole, which is widely used to increase the fatigue life of aircraft fuselage structures. In this paper, 3D finite element models were used to analyze the mandrel force, residual stress distribution and fatigue life of 7075 aluminum alloy after cold expansion, and the influences of the sleeve hardness, friction coefficient between mandrel and split sleeve, and the expansion ratio were investigated. The results show that with the increase in expansion ratio, the residual stress value, mandrel force and fatigue life of the specimen increase obviously. However, the hardness of the split sleeve and the friction coefficient between the mandrel and the sleeve have little effect on the residual stress, mandrel force and fatigue life.