Journal
COMPUTATIONAL MECHANICS
Volume 68, Issue 2, Pages 311-335Publisher
SPRINGER
DOI: 10.1007/s00466-021-02033-1
Keywords
Phase-field models; Ductile fracture; Plasticity; Three-point bending
Funding
- U.S. Department of Energy's National Nuclear Security Administration, USA [DE-NA0003525]
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A novel phase-field model for ductile fracture is developed within a consistent variational framework in the context of finite-deformation kinematics. The model introduces a new coupling mechanism between plasticity and fracture through a novel coalescence dissipation. Numerical examples and simulations show good agreement with experimental observations, validating the model's effectiveness in representing ductile fracture behavior.
A novel phase-field model for ductile fracture is presented. The model is developed within a consistent variational framework in the context of finite-deformation kinematics. A novel coalescence dissipation introduces a new coupling mechanism between plasticity and fracture by degrading the fracture toughness as the equivalent plastic strain increases. The proposed model is compared with a recent alternative where plasticity and fracture are strongly coupled. Several representative numerical examples motivate specific modeling choices. In particular, a linear crack geometric function provides an unperturbed ductile response prior to crack initiation, and Lorentz-type degradation functions ensure that the critical fracture strength remains independent of the phase-field regularization length. In addition, the response of the model is demonstrated to converge with a vanishing phase-field regularization length. The model is then applied to calibrate and simulate a three-point bending experiment of an aluminum alloy specimen with a complex geometry. The effect of the proposed coalescence dissipation coupling on simulations of the experiment is first investigated in a two-dimensional plane strain setting. The calibrated model is then applied to a three-dimensional calculation, where the calculated load-deflection curves and the crack trajectory show excellent agreement with experimental observations. Finally, the model is applied to simulate crack nucleation and growth in a specimen from a recent Sandia Fracture Challenge.
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