Springback behaviour of titanium alloy at room temperature by flexible free incremental sheet forming: experiments and simulations

Abstract

As an innovative small-batch forming method, flexible free incremental sheet forming (FFISF) utilizes two auxiliary sheets on both sides of the sheet metal to increase its hydrostatic stress, showing its promising advantages in rapidly fabricating sheet metal part of titanium alloy at room temperature. However, due to the significant springback of titanium alloy and complex deformation states in FFISF such as cyclic loading, bending and through-thickness stresses, accurate simulation of the springback of TC4 titanium alloy after FFISF remains challenging. To address this problem, this work adopts various flow stress equations, kinematic hardening models and anisotropic yield criteria to analyse the influence of constitutive relationship on the simulation accuracy of the springback for U-shaped TC4 parts at room temperature. By comparing simulation results with experimental data, key factors of constitutive models influencing the simulation accuracy are identified and the springback behaviour of TC4 sheet metal by FFISF is further elaborated. Finally, an accurate simulation of the springback after FFISF is achieved by utilizing appropriate constitutive models for TC4 titanium alloys at room temperature. This work offers notable benefits for facilitating the accurate manufacturing of complex titanium components using FFISF at room temperature, therefore expanding the potential of industrial application.