Strain-Rate-Dependent Tensile Deformation and Fracture of Monolayer Amorphous Graphene: A Reactive Molecular Dynamics Study

Abstract

Amorphous graphene (a-graphene) a 2D carbon network with short-range order but no long-range periodicity holds promise for flexible electronics and nanocoatings, yet its rate-dependent mechanics remain unclear. Reactive molecular dynamics (MD) simulations using the ReaxFF potential investigated the tensile deformation and fracture of monolayer a-graphene at 300 K. The stress–strain behavior exhibits linear elasticity, non-linear yielding, and abrupt fracture. At a baseline strain rate of ε̇ ≈ 10⁹ s⁻¹, the effective Young’s modulus is 345.2 GPa (~1/3 of pristine graphene) due to topological disorder and non-hexagonal (5-7-8) ring defects. Increasing the strain rate 2.5-fold to ε̇ ≈ 2.5 × 10⁹ s⁻¹ elevates the ultimate tensile strength from 138.2 to 158.0 GPa and fracture strain from 0.0933 to 0.1158. Failure initiates via stress concentration at under-coordinated defects, leading to micro-void nucleation, coalescence, and brittle cleavage. This rate sensitivity stems from competition between loading rate and thermal relaxation of strained C–C bonds