AN IMPROVED METHOD FOR THE APPLICATION OF BLANK-HOLDING FORCE CONSIDERING THE SHEET THICKNESS IN THE DEEP-DRAWING SIMULATION OF PLANAR ANISOTROPIC SHEET

Abstract

In the analysis of deep drawing, the tractional distribution due to the blank holding of the flange influences greatly the final deformation of the drawn cup. The tractional boundary conditions are related directly to the thickness distribution developed during the drawing process. However, the tractional boundary conditions are usually assumed by applying uniform nodal forces along the peripheral nodes of the flange. In the present work, the blank-holding force is considered to be distributed as a function of thickness over each node in the flange. During the process, when the nodal thickness in the flange reaches a critical value, the blank-holding force and accordingly the blank-holding traction are distributed such as to be assigned to the corresponding node according to the suggested scheme of thickness consideration. Deep drawing of circular and square cups is analyzed by using the rigid-plastic finite-element method considering planar anisotropy. The method is shown to improve convergence and stability as well as the prediction of ear development.