2D materials communicate with the environment through large area of surface. Recent experimental measurements have deepened our understanding of the friction between layers of 2D materials and suggested the interlayer properties, such as interlayer friction, can couple with intralayer properties and affect the overall behavior of multilayered 2D material systems. In this study, the effect of interlayer friction on asynchronous crack propogation and dissimilar crack paths is considered by integrating theoretical analysis and numerical simulation. It is found that the intact layer can postpone crack propogation in the neighbouring layer and cracks along dissimilar paths can communicate via interlayer sliding zone, resulting in a size-dependent fracture behavior.
Recent experimental measurements have discovered the fracture toughness of monolayer h-BN is much large than its intrinsic surface energy and based on DFT calculations toughening mechanisms of crack tip bifurcation and edge swapping due to the lattice asymmetry have been proposed. In this study, combining theoretical analysis and phase field (PF) modeling, we study the effect of the polarized edge stress and anisotropic fracture energy on the fracture of h-BN. It is found that polarized edge stress can contribute a mode II stress intensity factor (SIF) travelling with the crack tip and the competition between local lattice asymmetry and gloabl extrenal loading can result in a zigzag crack path with swaping branches.