Atomistic Simulation of Mode-I and Mode-II Fracture and Fatigue in Amorphous Carbon

Very little data exists in the literature on Mode II fracture and Mode I fatigue crack growth simulation for amorphous materials using steered molecular dynamics (SMD), and one of the goals of this paper is to fill this gap. Consequently, this paper explores fracture under Mode-II loading as well as Mode I fatigue loading in amorphous carbon, which is often used as a precursor in the manufacturing of carbon-carbon composites. Results for crack initiation in Mode-II, the corresponding fully developed fracture process zone (FPZ) profile, and crack propagation angle are presented using a novel “K-test” approach using SMD. For Mode-I fatigue loading, the gradual reduction in near crack tip material stiffness and fatigue crack growth is presented along with visualizations of fatigue crack growth. However, it should be noted that the fatigue loading frequency in MD is usually much higher than what one would observe in a real-life scenario.