The effects of through-thickness shear stress on the formability of sheet metal–A review

Abstract

The stress state of the sheet has a significant influence on the formability during the sheet metal forming process. Some research has shown that the through-thickness shear stress on the sheet can improve the formability of sheet metal. In order to provide a complete picture about the reasons and ways that the through-thickness shear stress affects the formability, this paper analyzes and summarizes the effects from three aspects: theory, numerical analyses, and experiments. Besides，the methods of generating through-thickness shear stress are discussed, and the research progresses of the M-K model considering the through-thickness shear stress are reviewed. Based on the establishment of the extended M-K model, the forming limit considering the through-thickness shear stress is predicted, and the mechanisms of through-thickness shear stress improving the formability are analyzed further. The numerical methods of analyzing through-thickness shear stress improve thickness uniformity of the sheet are also reviewed. The design of experimental setups and experimental methods for studying the influence of through-thickness shear stress based on friction and the interface tangential viscous adhesion stress on sheet formability are analyzed and compared. Finally, the future research orientation of the through-thickness shear stresses is proposed.