Fracture Stress and Failure Morphology of Graphene with a Nano-pore Geometry under Uniaxial Tension: A Molecular Dynamics Study

Abstract

Graphene exhibits remarkable optical, electrical, and mechanical characteristics. The transformation of pristine graphene into nanoporous membranes with expanded applications is enabled by precise defect engineering, specifically through the formation of nanopores. This study examined the fracture behaviour of graphene with a triangular nanopore geometry under uniaxial tensile strain using a molecular dynamics approach. The fracture stress decreased to 38.93% under ZZ loading and 33.28% under AC loading after the formation of the triangular pore. Consequently, the fracture strain decreased to 57.03% and 47.81% under ZZ and AC loading conditions, respectively. Nevertheless, the anisotropic fracture behaviour of porous graphene was not influenced by this substantial reduction in mechanical strength. The pre-fracture strain of graphene with a triangular pore decreased more at 10−4 ps−1 (low) than at 10−2 ps−1 (high) strain rates as the temperature increased from 100 K (low) to 500 K (high) under both tensile loading directions. In addition, the fracture-sequence analyses indicate that the upper pore-edge region is the primary control region for ZZ failure, while the two side lower regions are responsible for AC failure. This study provides useful physical insights for nanoporous graphene for molecular sieving systems, separation membranes and nanosensors.