Upper-bound analysis of equal channel angular extrusion using linear and rotational velocity fields

An upper-bound approach based on the rotational and linear velocity fields is used to analyze the equal channel angular extrusion process. Using this model, plastic deformation zone (PDZ) is divided into three rotational velocity fields. The equations and center axis of each velocity discontinuity surface are derived. The total power loss is optimized numerically with respect to the boundary points of discontinuity surfaces. Results show that PDZ becomes larger with increasing the constant friction factor and the inner corner radius. Also, the experimental and theoretical forces needed for the equal channel angular extrusion process are in a good agreement.