Springback prediction of titanium tube bending considering Bauschinger effect and Young's modulus variation

High strength titanium bent tubes present promising usages in advanced aircraft and spacecraft to achieve lightweight and improve overall performance. However, the high ratio of yield strength to Young's modulus results in significant springback in bending, which limits their forming accuracy. In this work, the Bauschinger effect and nonlinear unloading behavior of high strength Ti-3Al-2.5V tube are experimentally investigated. Then, to describe such behaviors, the Yoshida-Uemori (Y-U) two-surface hardening model and Chord unloading model are introduced into the elastoplastic constitutive framework and numerically implemented. Taking rotary draw (RDB) bending as a case, the springback angles are predicted and analyzed by comparison with the experimental results.