Investigation on three-roller cylindrical bending of 2060-T8 Al-Li alloy plate for aircraft fuselage skin components

Abstract

The aluminum-lithium alloy 2060-T8 is widely utilized in the fabrication of future aircrafts. With the application of this high-strength alloy, the severe shape variation after unloading has been challenging the traditional process for forming fuselage skin components. In this study, the three-roller bending process with the 2060-T8 alloy for fuselage skins was investigated with theoretical calculations, finite simulations and experiments. Uniaxial tensile tests of 2060-T8 alloy were carried out and three-roller cylindrical bending experiments were accomplished. The prediction with analytic models was conducted to determine the upper roller feeding and residual stress with the desired radius. To promote the predicting accuracy, an adaptive fitting method was adopted to determine the elastic-exponential hardening model variably. The same forming processes were also simulated with Abaqus software for comparison. Finally, the configuration and residual stress of the experimental plates were measured. The forming curves predicted with different approaches were presented in the comparison with measurements. The good agreement of the theoretical estimations verified the analytic models with variable material model. The crucial reason caused the decrease of predicting accuracy in theoretical calculation was revealed in the analysis and verifications.