Phase-field modeling of elastic-plastic fracture propagation in punch
through shear test
Abstract
Fracture initiation and propagation from a wellbore within a rock
formation exhibit nonlinear and inelastic behaviors. When the rock
material undergoes plastic deformation prior to failure, the classical
Griffith theory is no longer valid. In this study, a variational
phase-field approach is applied to model the inelastic behavior of
granite rock in a punch through shear test. The rock failure and the
fracture initiation and propagation during the loading was simulated and
compared to the corresponding experimental investigations. In this
numerical approach, the total local free energy is fully coupled with
solid deformation and computes the plastic strain rate. The code is
scripted in Multiphysics Object Oriented Simulation Environment (MOOSE).
The model is shown capable of reproducing the three point bending
benchmark problem and the evidenced phenomena from Punch Through Shear
(PTS) test encompassing mixed mode fracture pattern (Mode I, and Mode
II), and wing fractures. The numerical results show a good agreement in
stress-displacement curve with experimental data for critical energy
release rate of . Therefore, the granite sample’s fracture toughness for
Mode II is calculated to be 4.85 at no confining pressure.