Mechanical properties of pristine and nanoporous graphene

The Crack Angle of 60° Is the Most Vulnerable Crack Front in Graphene According to MD Simulations

Graphene is a type of 2D material with unique properties and promising applications. Fracture toughness and the tensile strength of a material with cracks are the most important parameters, as micro-cracks are inevitable in the real world. In this paper, we investigated the mechanical properties of triangular-cracked single-layer graphene via molecular dynamics (MD) simulations. The effect of the crack angle, size, temperature, and strain rate on the Young’s modulus, tensile strength, fracture toughness, and fracture strain were examined. We demonstrated that the most vulnerable triangle crack front angle is about 60°. A monitored increase in the crack angle under constant simulation conditions resulted in an enhancement of the mechanical properties. Minor effects on the mechanical properties were obtained under a constant crack shape, constant crack size, and various system sizes. Moreover, the linear elastic characteristics, including fracture toughness, were found to be remarkably influenced by the strain rate variations.

Multiscale numerical simulation of in-plane mechanical properties of two-dimensional monolayers

Many applications of two dimensional (2D) materials are often achieved through strain engineering, which is directly dependent on their in-plane mechanical characteristics. Therefore, understanding the in-plane mechanical characteristics of the 2D monolayers becomes imperative. Nevertheless, direct experimental measurements of in-plane mechanical properties of 2D monolayers face great difficulties due to the issues related to the availability of high-quality 2D materials and sophisticated facilities. As an alternative, numerical simulation has the potential to theoretically predict such properties. This review presents some recent progress in numerically exploring the in-plane mechanical properties of 2D materials, including first-principles density functional theory, force-field based classical molecular dynamics, and the finite-element method. The relevant case studies are provided to describe the applications of these methods along with their pros and cons. We hope that the multiscale simulation methods discussed in this review will inspire new ideas and boost further advances of the computational study on the in-plane mechanical properties of 2D materials.

The recent progress of multiscale numeric methods for investigating in-plane mechanical properties of 2D monolayers is reviewed.

Temperature Effects on the Fracture Dynamics and Elastic Properties of Popgraphene Membranes

Popgraphene (PopG) is a new 2D planar carbon allotrope which is composed of 5-8-5 carbon rings. PopG is intrinsically metallic and possesses excellent thermal and mechanical stability. In this work, we report a detailed study of the thermal effects on the mechanical properties of PopG membranes using fully-atomistic reactive (ReaxFF) molecular dynamics simulations. Our results showed that PopG presents very distinct fracture mechanisms depending on the temperature and direction of the applied stretching. The main fracture dynamics trends are temperature independent and exhibit an abrupt rupture followed by fast crack propagation. The reason for this anisotropy is due to the fact that y-direction stretching leads to a deformation in the shape of the rings that cause the breaking of bonds in the pentagon-octagon and pentagon-pentagon ring connections, which is not observed for the x-direction. PopG is less stiff than graphene membranes, but the Young's modulus value is only 15 % smaller.

Path-integral simulation of graphene monolayers under tensile stress

Finite-temperature properties of graphene monolayers under tensile stress have been studied by path-integral molecular dynamics (PIMD) simulations.