MODELING DRAWBEADS WITH FINITE-ELEMENTS AND VERIFICATION

Drawbeads are commonly used in deep drawing processes to control the f low of the blank during the forming operation. In finite element simul ations of deep drawing the drawbead geometries are seldom included bec ause of the small radii; because of these small radii a very large num ber of elements is required in 3-D simulations. To cope with this prob lem, a 2-D analysis of the drawbead has been performed and the calcula ted restraining force will be applied in the near future in 3-D simula tions with an equivalent drawbead element. Modelling drawbeads by only applying an additional restraining force is not satisfactory. During the flow of the material through a drawbead, the strain distribution c hanges and the material usually becomes thinner. These effects must be incorporated in the equivalent drawbead element. For the modelling of the drawbead a 2-D plane strain finite element model was developed. S everal simulations were carried out to investigate the behaviour of th e drawbead. Various geometries were investigated, the friction coeffic ient was varied and also the frictionless case was taken into account. To verify the model an experimental set-up was built. An extensive se t of drawbead geometries was used. The results are compared with the f inite element calculations and the similarity is very satisfactory.