Abstract: An upper bound model for analyzing extrusion process is proposed. In this model, the deformation zone surface is constructed by interpolating the arbitrarily cross-sectional shapes of the billet and the section, the axial velocity distribution is considered in the admissible velocity field, the pseudo-independent parameters in the deformation zone surface and the admissible velocity field are calculated by optimum method. Analytical results show the upper bound method presented here is accurate, the calculating results are coincident with the experimental ones.

Key words: section, extrusion, upper bound method, die