Modelling and sensitivity analysis of twist springback in deep drawing of dual-phase steel

Abstract

Twist springback induced by unbalance elastic deformation and residual stresses in a sheet after a forming is of particular importance and complexity. The twist springback can be influenced by several factors, such as blank shape geometry, material anisotropy and sheet piercing. A sensitivity study of these parameters provides insight into the twist springback control of rail parts. In the present work, a more reasonable evaluation of twist springback of a long member with respect to the central principal inertia axes of the longitudinal cross-section was proposed. In order to explore the source of twist springback, the analysis of the relationship between torsion moment and twist angle was introduced. Mechanical tests including uniaxial tension, forward-reverse shear and hydraulic bulge testswere conducted to determine the material constitutive parameters of a DP500 steel. Several keymodelling techniques including the friction coefficient identification and digital image correlation were performed for improving the robustness of twist springback prediction of a typical design benchmark of a curved rail channel formed by deep drawing. Finally, the sensitivity of the constitutive model, material direction and blank piercing on twist springbackwas analysed in-depth and discussed based on experimental and numerical results. (C) 2015 Elsevier Ltd. All rights reserved.