The double cold expansion strengthening technology can ensure that the hole has enough strengthened effect

and realize the close fit between bushing and the hole edge

so as to improve the fatigue life of connectors effectively. Residual stress distribution and fatigue life of double cold expanded hole were studied by simulation method. Firstly

a finite element model for the double cold expansion of TB6 titanium alloy components was established to analyze the accuracy of the simulation model. Secondly

based on the simulation results

the fatigue life of the double cold expanded hole was analyzed by MSC.Fatigue software. Finally

the effect of the hole diameter deviation and the expansion lubrication condition on the fatigue performance was taken into consideration. The results show that the stress concentration on the hole wall can be effectively alleviated by the double cold expansion process. The fatigue failure position transferred from the hole edge to the position far away. Furthermore

a constant stress level in the direction of the smallest cross-section with different apertures occurs. It is also found that the excessive diameter deviation has a negative effect on the fatigue life

where good lubrication condition is beneficial to the fatigue performance.