Authors: Langenfeld, K.
Kurzeja, P.
Mosler, J.
Title: How regularization concepts interfere with (quasi-)brittle damage: a comparison based on a unified variational framework
Language (ISO): en
Abstract: Three regularization concepts are assessed regarding their variational structure and interference with the predicted physics of (quasi-)brittle damage: the fracture energy concept, viscous regularization and micromorphic regularization. They are first introduced in a unified variational framework, depicting how they distinctively evolve from incremental energy minimization. The analysis of a certain time interval of a one-dimensional example is used to show how viscous and micromorphic regularization retains well-posedness within the softening regime. By way of contrast, the fracture energy concept is characterized by ill-posedness—as known from previous non-variational analyses. Numerical examples finally demonstrate the limitations and capabilities of each concept. The ill-posed local fracture energy concept leads by its design to a spatially constant fracture energy—in line with Griffith’s theory. The viscous regularization, in turn, yields a well-posed problem but artificial viscosity can add a bias to unloading and fracture thickness. Furthermore, and even more important, a viscous regularization does not predict a spatially constant fracture energy due to locally heterogeneous loading rates. The well-posed micromorphic regularization is in line with the underlying physics and does not show this undesired dependency. However, it requires the largest numerical efforts, since it is based on a coupled two-field formulation.
Subject Headings: Variational framework
Damage mechanics
Fracture energy concept
Viscous regularization
Micromorphic regularization
Subject Headings (RSWK): Schadensmechanik
Numerisches Modell
Spröder Werkstoff
Issue Date: 2022-09-05
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Appears in Collections:Institut für Mechanik

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