Role of lattice discreteness on brittle fracture: Atomistic simulations versus analytical models

By means of thorough atomistic simulations an energy-based theory, named quantized fracture mechanics, is commented and validated. This approach modifies continuum linear elastic fracture mechanics by introducing the hypothesis of discrete crack propagation, taking into account the discreteness of the crystal lattice. We investigate at an atomistic level the crack energy resistance for a matrix of silicon carbide with an isolated crack, and the effect on the stress at the crack tip due to a second phase particle. In both cases our results show that, while atomistic simulations provide the most basic level of understanding of mechanical behavior in nanostructured brittle materials, quantized fracture mechanics is able to effectively incorporate the main lattice-related feature, thus enlarging the realm of continuum modeling.