An upper-bound analysis of the tube extrusion process

In this paper a new upper-bound approach is used to analyze the tube extrusion process. A kinematically admissible velocity field is developed to evaluate the internal power and the power dissipated on frictional and velocity discontinuity surfaces. The total power is optimized with respect to the die angle. The optimum die angle and the critical die angle at which a dead zone is formed are determined. The effect of constant friction factor and reduction in area on the optimum die angle is predicted. in addition, the role of die angle on the relative extrusion pressure is investigated. Comparison of the experimental and theoretical load-displacement curves shows a good agreement. (c) 2007 Elsevier B.V. All rights reserved.