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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 22
ADVANCES IN FINITE ELEMENT TECHNIQUES
Edited by: M. Papadrakakis and B.H.V. Topping
Paper IV.1

Microphysically based Material Model Applied to Nonlinear Structural Analysis

U. Kowalsky, M. Schwesig and H. Ahrens

Institut für Statik, Technische Universität Braunschweig, Braunschwieg, Germany

Full Bibliographic Reference for this paper
U. Kowalsky, M. Schwesig, H. Ahrens, "Microphysically based Material Model Applied to Nonlinear Structural Analysis", in M. Papadrakakis, B.H.V. Topping, (Editors), "Advances in Finite Element Techniques", Civil-Comp Press, Edinburgh, UK, pp 117-126, 1994. doi:10.4203/ccp.22.4.1
Abstract
In this contribution the applicability of the microphysically based "unified" model firstly introduced by Estrin is investigated resulting in a proposal for a modified version. The original constitutive equations are restricted to isotropic hardening. For the description of kinematic hardening the material model is extended by introducing the concept of effective stresses.

For the identification of the parameters of the model a specially structured evolution strategy can be applied successfully. From experimental and microphysical considerations a starting- parameter vector can be derived by which the convergence of the iteration process is strongly accelerated.

As a technical application of the material law the casing structure of an extrusion press is investigated. Results derived from both, Estrin's model and the extended model, are compared. The applied finite element formulation employs implicit time integration and full Newton-Raphson technique based on a consistent linearization of the constitutive equations.

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