Investigation of experimental flow patterns for plane strain extrusion of hardening materials with slipline field methods

Abstract
The paper describes a method of obtaining experimental flow patterns in extrusion of aluminium alloys through tapered dies, of constructing slipline meshes from the velocity fields and of carrying out stress analyses with hardening rules based on measured stress-strain relations in compression. The slipline meshes are patched together from local Hencky-Prandtl nets which are perturbed to obtain the best overall match between the computed velocity field and that of the experimental flow pattern, by using an iterative optimization procedure. The extrusion forces computed from the stress fields and from the plastic work are compared with the measured forces and with those predicted by the corresponding solutions for rigid-perfectly plastic material.