U-R relationship prediction method for aluminum alloy circular tube free-bending process based on sensitivity analysis of material parameters

The bending radius (R) of the bending component is defined by the deflection (U) of the bending die in the tube free-bending process. The U-R relationship is the key factor to obtain the precise geometry size of the complex bending tubular components. Therefore, this study aims at proposing a new method to predict the U-R relationship for the arbitrary power hardening aluminum alloy (Al alloy) circular tube based on the U-R relationship of the reference material and the sensitivity analysis of material parameters, which may reduce many experimental works. In the current study, AA1100 alloy was set as the reference material, and the effects of each material parameter on the U-R relationship were investigated by carrying out the deformation and sensitivity analysis of the FEA simulation results. The results show that the bending radius increases with the decrease of elastic modulus (E), density (rho), and strain-hardening exponent (n) and the increase of strength coefficient (K) and initial yield stress (sigma(s)), where sigma(s) has the greatest influence on the U-R relationship. Moreover, the U-R relationship prediction method for arbitrary power hardening Al alloy circular tube was presented based on the sensitivity analysis of the reference material. Finally, the bending tests of the AA6061-T6 tubes were carried out to prove the accuracy of the U-R relationship prediction method. The bending results show that the experimental U-R relationship of the AA6061-T6 tube was consistent with the predicted value, and the prediction method had good applicability to power hardening Al alloy circular tube.