Failure criterion for graphene in biaxial loading—a molecular dynamics study

Abstract

Molecular dynamics simulations are carried out in order to develop a failure criterion for infinite/bulk graphene in biaxial tension. Stresses along the principal edge configurations of graphene (i.e. armchair and zigzag directions) are normalized to the corresponding uniaxial ultimate strength values. The combinations of normalized stresses resulting in the failure of graphene are used to define failure envelopes (limiting stress ratio surfaces). Results indicate that a bilinear failure envelope can be used to represent the tensile strength of graphene in biaxial loading at different temperatures with reasonable accuracy. A circular failure envelope is also introduced for practical applications. Both failure envelopes define temperature-independent upper limits for the feasible combinations of normalized stresses for a graphene sheet in biaxial loading. Predicted failure modes of graphene under biaxial loading are also shown and discussed.

Electrical conductivity and mechanical performance of multiwalled CNT‐filled polyvinyl chloride composites subjected to tensile load

“…It can be inferred that the growth of fracture in the specimen is governed by the comparative resistances to cracking of the polymer matrix and the inclusions (i.e., CNT bundles/individuals). Fractures were initiated from inside the largest bundles between 18–36% strain, which is close to the range of strain at failure reported for CNTs and graphene at room temperature (i.e., 8–20%). The initiation of the fractures from bundles is possibly due to the weak van der Waals interactions between MWCNT individuals, and the small shear strength between the MWCNT concentric layers (the average shear strength for high‐quality graphite is approximately 0.48 MPa).…”

Long triple carbon chains formation by heat treatment of graphene nanoribbon: Molecular dynamics study with revised Brenner potential

“…Both the bottom-up process of chain formation as a result of C10H2 molecules fusion [20] and top-down chain formation by rupture of bulk graphene [41,43] and GNRs [38][39][40]42,44], evaporation of GNRs at high temperature [35,36], and as a result of GNR etching by electron irradiation [37] have been studied by ab initio and classical atomistic simulations. In these simulations, the longest chains consisting of 15-20 atoms have been observed for graphene rupture along grain boundaries [43] and at high temperature [44].…”

“…Classical MD simulations performed here reveal a principally different atomistic mechanism of chain formation and predict formation of triple, double and single carbon chains of up to hundreds of atoms in length during heating of zigzagedged GNRs with 3 atomic rows (3-ZGNR). On the other hand, we show that heating of 4-ZGNR leads to formation only of short chains [38][39][40][41][42][43][44] (the nomenclature of GNRs from Ref. 45 is used).MD simulations based on empirical potentials are widely used to get insight into properties of systems of a large size and processes taking a long time, which are not accessible for MD simulations based on tight-binding potentials and ab initio MD.…”

Mechanical properties of carbon nanotube‐filled polyethylene composites: A molecular dynamics simulation study

“…Consequently, CNT exhibits a non-physical strain-hardening behavior at a C-C bond length of 2.0 Å. In this study, as proposed by several researchers [23,24], both the lower and upper limits (i.e., 1.7 and 2.0 Å) were set to 2.0 Å to solve the aforementioned cutoff problem while preserving the ability to describe bond breaking and the nearest-neighbor character of interactions.…”