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Dynamic crack propagation with a variational phase-field model: limiting speed, crack branching and velocity-toughening mechanisms

Abstract : We address the simulation of dynamic crack propagation in brittle materials using a regularized phase-field description, which can also be interpreted as a damage-gradient model. Benefiting from a variational framework, the dynamic evolution of the mechanical fields are obtained as a succession of energy minimizations. We investigate the capacity of such a simple model to reproduce specific experimental features of dynamic in-plane fracture. These include the crack branching phenomenon as well as the existence of a limiting crack velocity below the Rayleigh wave speed for mode I propagation. Numerical results show that, when a crack accelerates , the damaged band tends to widen in a direction perpendicular to the propagation direction, before forming two distinct macroscopic branches. This transition from a single crack propagation to a branched configuration is described by a well-defined master-curve of the apparent fracture energy Γ as an increasing function of the crack velocity. This Γ(v) relationship can be associated, from a macroscopic point of view, with the well-known velocity-toughening mechanism. These results also support the existence of a critical value of the energy release rate associated with branching: a critical value of approximately 2Gc is observed i.e. the fracture energy contribution of two crack tips. Finally, our work demonstrates the efficiency of the phase-field approach to simulate crack propagation dynamics interacting with heterogeneities, revealing the complex interplay between heterogeneity patterns and branching mechanisms.
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https://hal-enpc.archives-ouvertes.fr/hal-01390233
Contributeur : Jérémy Bleyer <>
Soumis le : mardi 1 novembre 2016 - 09:57:12
Dernière modification le : mardi 15 octobre 2019 - 01:20:48
Archivage à long terme le : : mardi 14 mars 2017 - 23:08:22

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Jeremy Bleyer, Clément Roux-Langlois, Jean-François Molinari. Dynamic crack propagation with a variational phase-field model: limiting speed, crack branching and velocity-toughening mechanisms. International Journal of Fracture, Springer Verlag, 2017, 204 (1), pp.79--100. ⟨10.1007/s10704-016-0163-1⟩. ⟨hal-01390233⟩

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