Phase field modeling of frictional slip with slip weakening/strengthening under non-isothermal conditions

Cracks, veins, joints, faults, and ocean crusts are strong discontinuities of different length scales that can be found in many geological formations. While the constitutive laws for the frictional slip of these interfaces have been the focus of decades-long geophysical research, capturing the evolving geometry such as branching, coalescence, and the corresponding interplay between frictional slip and the mode II crack growth in compression remains a challenging task. This work employs a phase field framework for frictional contact originated in Fei and Choo (2020), s.t. these strong discontinuities are represented by implicit functions and the frictional responses of the transitional damage zone is approximated by a diffusive constitutive law that captures the coupling between the bulk and interfacial plasticity. To replicate the rate dependence and size effects commonly exhibited in frictional interfaces, we propose a regularized constitutive law for the slip weakening/strengthening at different loading rates and temperature regimes. Numerical examples are provided to show that the regularized model may converge into the strong-discontinuity counterpart and capture the frictional response along geometrically complex interfaces. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study utilizes a phase field framework to investigate the frictional slip of strong discontinuities in geological formations of different length scales, proposing a regularized constitutive law adjusted based on loading rates and temperature ranges. Numerical examples demonstrate that this model can capture the frictional response along complex interfaces.