Residual Stresses of Al-Li Alloy Sheets in Automatic Drilling Riveting Process

Residual stress induced by riveting process is critical to the fatigue life of riveted structures.In this paper,the principal stress method was employed to calculate the pressure on the surface of rivet hole and the stress between upset head and sheet.The radial and circumferential residual stresses were solved by using the spatial axisymmetric elastoplasticity theory,where the sheets were equivalent to a thickwalled cylinder.The change of residual stresses caused by various process parameters was explained by the analytical results reasonably.The results show that the circumferential residual stress decreases with the increase of the upset head height and the rivet hole diameter.However,the radial residual stress is approximately independent of the two parameters.The distribution of residual stress on the surface of rivet hole along the thickness direction was investigated by using the finite element method.The results indicate that the residual stress on the faying surface is discontinuous.A C-shaped distri