Influence of local features on twist springback of high-strength steel long channels

With the wide use of high-strength steel (HSS) in structural body parts, the twist springback of high-strength steel parts has received extensive attention. Unlike automotive panels, structural body parts are arranged with many local features to meet functional requirements. The aim of this study is to investigate the influence of local features on twist springback to optimize the design of local features to reduce twist springback. In this paper, a typical long channel part (A-pillar upper inner plate) is taken as the object of study. A suitable location division method for this type of part is proposed to investigate the changes in twist springback and cross-sectional stresses in the part before and after the addition of local features at different locations through finite element simulations. The results show that the local features affect the stiffness and stress distribution of the parts and significantly affect the twist springback of the parts. Finally, the research results guided the optimization of the local feature design of an A-pillar upper inner plate, resulting in a remarkable 37% and 61% decrease in twist springback at the left and right ends of the optimized part, respectively. In addition, stamping molds were developed for optimized parts, and experiments were carried out to verify the effectiveness of the law and the reliability of the finite element model.