Molecular Dynamics approach for Fracture Simulation along a Weakly Bonded Interface

Abstract

Opening mechanisms for fractures (joints) characterized by weak bonding (nano-micro scale cracks) in low-porosity rock play a key role in shale oil and shale gas development through staged hydraulic fracturing. We explore the cohesive interface strength of two weakly bonded slabs of Polymethylmethacrylate (PMMA) with nanoscale Molecular Dynamics (MD) methods, calibrated to experimental data and simulated by the Finite Element Method (FEM). The proper stress/strain state at the weakly bonded interface is determined because it is required for MD simulation. Then, we develop a representative PMMA structure as an input for LAMMPS © software to simulate a tensile strength test. Results including per-atom stress values and pressures in different components are extracted, and we note that the fracture location and its behavior deduced from MD simulations follows experimental results. The total force for this simulation is close to 80 × 10 6 N, and we can use this parameter to reflect the fracture behavior of the weakly bonded PMMA slabs with an acceptable accuracy, considering the levels of uncertainty.