Computer-aided evaluation of workability in bulk forming processes

A computer-aided workability evaluation system, (CAWES), has been developed and coupled to an elasto-plastic large-strain finite-element package to check for ductile fracture at all locations in bulk formed workpieces, using different workability criteria. To compare the results of these criteria, a relative fracture index, gamma, is introduced, which is a dimensionless parameter measuring the proximity of a material to fracture. The new procedure is used to determine the workability limits in upsetting and bolt heading, and it renders itself useful as a design tool. This is demonstrated by an example where a selection is made from two alternative preform designs for the backward extrusion of a cup-shaped product. (C) 1998 Elsevier Science S.A. All rights reserved.