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Register a new userMechanical Properties and Fracture Phenomenon of Defected Monolayer Indium Selenide: A Molecular Dynamics Study
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Added by
Tanmay Sarkar Akash
Publication date
2020
fields
Physics
and research's language is
English
Authors
Md. Faiyaz Jamil
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In this study, we report the mechanical properties and fracture mechanism of pre-cracked and defected InSe nanosheet samples using molecular dynamics (MD) simulations. We noticed that the failure of pre-cracked and defected InSe nanosheet is governed by brittle type fracture. Armchair directional bonds exhibit a greater resistance for crack propagation relative to the zigzag directional ones. Thus, fracture strength of the pre-cracked sheet is slightly higher for zigzag directional loading than that for armchair. We evaluated the limitation of the applicability of Griffiths criterion for single layer (SL) InSe sheet for nano-cracks as the brittle failure of Griffith prediction demonstrates significant differences with the MD fracture strength. We inspected the effect of temperature on the mechanical properties of the pre-cracked samples of SLInSe. We also discussed the fracture mechanism of both defected and pre-cracked structure at length.
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Ebert et al. [Phys. Rev. Lett. 77, 3827 (1996)] have fractured icosahedral Al-Mn-Pd single crystals in ultrahigh vacuum and have investigated the cleavage planes in-situ by scanning tunneling microscopy (STM). Globular patterns in the STM-images were interpreted as clusters of atoms. These are significant structural units of quasicrystals. The experiments of Ebert et al. imply that they are also stable physical entities, a property controversially discussed currently. For a clarification we performed the first large scale fracture simulations on three-dimensional complex binary systems. We studied the propagation of mode I cracks in an icosahedral model quasicrystal by molecular dynamics techniques at low temperature. In particular we examined how the shape of the cleavage plane is influenced by the clusters inherent in the model and how it depends on the plane structure. Brittle fracture with no indication of dislocation activity is observed. The crack surfaces are rough on the scale of the clusters, but exhibit constant average heights for orientations perpendicular to high symmetry axes. From detailed analyses of the fractured samples we conclude that both, the plane structure and the clusters, strongly influence dynamic fracture in quasicrystals and that the clusters therefore have to be regarded as physical entities.
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In this work, we report on the mechanical responses and fracture behavior of pristine and defected monolayer 1T-Titanium Disulfide using classical molecular dynamics simulation. We investigated the effect of temperature, strain rate and defect ratio on the uniaxial tensile properties in both armchair and zigzag direction. We found that monolayer TiS2 shows isotropic uniaxial tensile properties except for failure strain which is greater in zigzag direction than armchair direction. We also observed a negative correlation of ultimate tensile strength, failure strain and youngs modulus with temperature and defect ratio. Results depicts that strain rate has no effect on the youngs modulus of monolayer TiS2 but higher strain rate results in higher ultimate tensile strength and failure strain.
As graphene became one of the most important materials today, there is a renewed interest on others similar structures. One example is silicene, the silicon analogue of graphene. It share some the remarkable graphene properties, such as the Dirac cone, but presents some distinct ones, such as a pronounced structural buckling. We have investigated, through density functional based tight-binding (DFTB), as well as reactive molecular dynamics (using ReaxFF), the mechanical properties of suspended single-layer silicene. We calculated the elastic constants, analyzed the fracture patterns and edge reconstructions. We also addressed the stress distributions, unbuckling mechanisms and the fracture dependence on the temperature. We analysed the differences due to distinct edge morphologies, namely zigzag and armchair.
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