arXiv subjects

Wjefferson H. S. Brandão

Publications and source records attributed to Wjefferson H. S. Brandão.

3 recordsLinked to original sources

arXiv2023

Exploring the Elastic Properties and Fracture Patterns of Me-Graphene Monolayers and Nanotubes through Reactive Molecular Dynamics Simulations

Me-graphene (MeG) is a novel two-dimensional (2D) carbon allotrope. Due to its attractive electronic and structural properties, it is important to study the mechanical behavior of MeG in its monolayer and nanotube topologies. In this work, we conducted fully atomistic reactive molecular dynamics simulations using the Tersoff force field to investigate their mechanical properties and fracture patterns. Our results indicate that Young's modulus of MeG monolayers is about 414 GPa and in the range of 421-483 GPa for the nanotubes investigated here. MeG monolayers and MeGNTs directly undergo from elastic to complete fracture under critical strain without a plastic regime.

cond-mat.mtrl-sci↗

arXiv2022

Fully Atomistic Molecular Dynamics Simulations of Elastic Properties of Tetragraphene Monolayer

A quasi-2D semiconductor carbon allotrope called tetrahexcarbon, also named tetragraphene, was recently proposed featuring an unusual structure combining squared and hexagonal rings. Mechanical and electronic properties of tetragraphene have been predicted based on first-principles Density Functional Theory (DFT) calculations. However, a comprehensive study of its mechanical behavior under different temperatures is still lacking. In this work, using fully atomistic reactive molecular dynamics (MD) simulations, we investigate the mechanical properties of monolayer tetragraphene under tensile strain from the linear regime up to the complete structural failure (fracture). Different temperatures were considered and the results were compared to that of two other known planar carbon allotropes: graphene and penta-graphene. One interesting result is that tetragraphene experiences a transition from crystalline to an amorphous structure by either temperature or tension application. At room temperature, the critical strains along the two orthogonal unit-cell directions of tetragraphene are 38\% and 30\%, which is higher than that for graphene and penta-graphene. Tetragraphene Young's modulus values along its directions are from three to six times smaller than that of graphene and about 57\% that of penta-graphene at room temperature. Ultimate tensile strength values along the two directions of tetragraphene were obtained and also shown to be smaller than that of graphene and penta-graphene.

cond-mat.mtrl-sci↗

arXiv2020

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.

cond-mat.mtrl-sci↗