FE-ANALYSIS OF THE RECIPIENT OF AN EXTRUSION PRESS APPLYING MICROSTRUCTURE-RELATED MATERIAL MODELS

In this contribution, the applicability of the microphysically based ' 'unified'' model first introduced by Estrin is investigated resulting in a proposal for a modified version. The original constitutive equati ons are restricted to isotropic hardening. For the description of kine matic hardening the material model is extended by introducing the conc ept of effective stresses. A specially structured evolution strategy i s applied successfully to identify the parameters of the model. From e xperimental and microphysical considerations, a starting-parameter vec tor is derived by which the convergence of the iteration process is st rongly accelerated. As a technical application, the casing structure o f an extrusion press is investigated. The applied finite element formu lation employs implicit time integration and full Newton-Raphson techn ique based on a consistent linearization of the constitutive equations . (C) 1997 Civil-Comp Ltd and Elsevier Science Ltd.