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

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• 作者：Jérémy Bleyer ; Clément Roux-Langlois…
• 关键词：Dynamic fracture ; Crack branching ; Brittle materials ; Phase ; field model ; Damage ; gradient model
• 刊名：International Journal of Fracture
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：204
• 期：1
• 页码：79-100
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Characterization and Evaluation of Materials; Classical Mechanics; Civil Engineering; Automotive Engineering; Mechanical Engineering;
• 出版者：Springer Netherlands
• ISSN：1573-2673
• 卷排序：204

文摘

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 \(\varGamma \) as an increasing function of the crack velocity. This \(\varGamma (v)\) 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 2\(G_c\) 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.