The effect of remote and internal crack stresses on mixed-mode brittle fracture propagation of open cracks under compressive loading

The standard mixed-mode fracture propagation models, based on near-tip stress approximations, have limited application for fractures under far-field compressive loading. Most studies in engineering mechanics have focused on extending or modifying the standard models to solve mixed-mode fracture propagation under tensile loading. However, for geomechanics and geologic applications, the ambient stress is compressive, and internal fluid pressure or frictional stress can play an important role in the near-tip stress field altering the predicted propagation path. In this study, we modify the maximum tangential principal stress (MTPS) criterion to improve fracture propagation path predictions relative to published experimental results under both tensile and compressive external loadings. In addition, new experimental results on open cracks under compressive loading were consistent with our proposed model. Accurate propagation path predictions are independent on whether small scale yielding conditions are met in the experiments. Overall, the modified MTPS-criterion proved capable for predicting propagation paths for open cracks under compressive far-field loading.