Optimization of boost condition and axial feeding on tube bending and hydro-forming process considering formability and spring-back

Finite element simulations were performed for the sequential procedures of bending and hydro-forming of DP590 tubes in order to optimize the process parameters, in particular, the boost condition and axial feeding in the sequential forming processes considering formability and spring-back. The effects of the material property, including strain-rate sensitivity on formability as well as spring-back were also evaluated numerically. As for the constitutive law, the isotropic hardening law was used along with the non-quadratic anisotropic yield function, Yld2000-2d. Forming limit diagrams were calculated based on Hill’s bifurcation theory and the MK theory. In order to characterize the material properties, tensile tests were performed for both the DP590 sheet and tube.