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

In the analysis of deep drawing, the tractional distribution due to th e blank holding of the flange influences greatly the final deformation of the drawn cup. The tractional boundary conditions are related dire ctly to the thickness distribution developed during the drawing proces s. 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 dis tributed as a function of thickness over each node in the flange. Duri ng the process, when the nodal thickness in the flange reaches a criti cal value, the blank-holding force and accordingly the blank-holding t raction are distributed such as to be assigned to the corresponding no de according to the suggested scheme of thickness consideration. Deep drawing of circular and square cups is analyzed by using the rigid-pla stic finite-element method considering planar anisotropy. The method i s shown to improve convergence and stability as well as the prediction of ear development.