A fast and robust numerical treatment of a gradient-enhanced model for brittle damage

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  • Ruhr-Universität Bochum
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Original languageEnglish
Pages (from-to)151-180
Number of pages30
JournalInternational Journal for Multiscale Computational Engineering
Volume17
Issue number2
Publication statusPublished - 2019
Externally publishedYes

Abstract

Damage processes are modeled by a softening behavior in a stress/strain diagram. This reveals that the stiffness loses its ellipticity and the energy is thus not coercive. A numerical implementation of such ill-posed problems yields results that are strongly dependent on the chosen spatial discretization. Consequently, regularization strategies have to be employed that render the problem well-posed. A prominent method for regularization is a gradient enhancement of the free energy. This, however, results in field equations that have to be solved in parallel to the Euler-Lagrange equation for the displacement field. An usual finite element treatment thus deals with an increased number of nodal unknowns, which remarkably increases numerical costs. We present a gradient-enhanced material model for brittle damage using Hamilton’s principle for nonconservative continua. We propose an improved algorithm, which is based on a combination of the finite element and strategies from meshless methods, for a fast update of the field function. This treatment keeps the numerical effort limited and close to purely elastic problems. Several boundary value problems prove the mesh-independence of the results.

Keywords

    Brittle damage, Finite element method, Gradient-enhanced regularization, Meshless method, Operator split

ASJC Scopus subject areas

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A fast and robust numerical treatment of a gradient-enhanced model for brittle damage. / Junker, Philipp; Schwarz, Stephan; Jantos, Dustin Roman et al.
In: International Journal for Multiscale Computational Engineering, Vol. 17, No. 2, 2019, p. 151-180.

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AU - Junker, Philipp

AU - Schwarz, Stephan

AU - Jantos, Dustin Roman

AU - Hackl, Klaus

N1 - Publisher Copyright: © 2019 by Begell House, Inc. Copyright: Copyright 2019 Elsevier B.V., All rights reserved.

PY - 2019

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N2 - Damage processes are modeled by a softening behavior in a stress/strain diagram. This reveals that the stiffness loses its ellipticity and the energy is thus not coercive. A numerical implementation of such ill-posed problems yields results that are strongly dependent on the chosen spatial discretization. Consequently, regularization strategies have to be employed that render the problem well-posed. A prominent method for regularization is a gradient enhancement of the free energy. This, however, results in field equations that have to be solved in parallel to the Euler-Lagrange equation for the displacement field. An usual finite element treatment thus deals with an increased number of nodal unknowns, which remarkably increases numerical costs. We present a gradient-enhanced material model for brittle damage using Hamilton’s principle for nonconservative continua. We propose an improved algorithm, which is based on a combination of the finite element and strategies from meshless methods, for a fast update of the field function. This treatment keeps the numerical effort limited and close to purely elastic problems. Several boundary value problems prove the mesh-independence of the results.

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