Shear Deformation And Thickness Stress In Corner Fill

Abstract

Corner fill is a simple benchmark intended to gain knowledge of tube hydroforming and to evaluate hydroforming parameters. In corner fill, an originally round tube is put into a cylindrical die with square cross-sections. Under applied internal pressure, the tube expands in and fills the corners of the die. Corner fill has been studied by using finite element method. The analyses, however, failed to correctly predict the burst of the tube. In this paper, a two-dimensional implicit-static plane strain finite element model is used to study the important mechanical parameters of deformation, including shear deformation and thickness stress, of the tube. The purpose of this paper is to try to explain why the existing failure criteria, including the forming limit diagram and plastic strain criterion, cannot correctly predict burst failures in corner fill. In particular, quantitative values were obtained for shear deformation and thickness stress in a corner filled tube.