Abstract
A hypothesis was presented concerning the effect of the axial residual stress at the first thread root of a bolt on its fatigue strength. However, this hypothesis has not yet been verified since the residual stress which may exist locally around the thread root can neither be measured nor estimated with sufficient accuracy. The final goal of this study is to quantify the effect of the residual stress on the fatigue strength of a bolt. As the first step, the residual stress at the root of groove-rolled specimens were measured by X-ray method, and it was found that the maximum compressive residual stress was generated at the inner layer about 0.5 mm from the surface. In this report, FE analysis with simplified three-dimensional model was performed to seek the appropriate boundary conditions for two-dimensional plane strain FE analysis. The processing force calculated by plane strain analysis shows good agreement with that of simplified three-dimensional analysis and of the experiment. Finally, there is a possibility that such a residual stress distribution could be simulated by FE analysis with simple plane strain model.
