Computational Materials and Modelling
Aristides D. Zdetsis; Shanawer Niaz
Abstract
We demonstrate that a suitable atomistic method with judicially selected nanoclusters/ nanocrystals (in real space) supplemented with general symmetry and dimensionality arguments, can give surprisingly good results for macroscopic properties of the infinite crystalline solid, such as bandgaps, cohesive ...
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We demonstrate that a suitable atomistic method with judicially selected nanoclusters/ nanocrystals (in real space) supplemented with general symmetry and dimensionality arguments, can give surprisingly good results for macroscopic properties of the infinite crystalline solid, such as bandgaps, cohesive energies, as well as aromaticity (if any), at minimal computational cost and maximum physical insight. For graphene on top of these properties the present approach can successfully describe in real space and illuminate many of its exotic properties, which are usually introduced in k-space, such as Dirac points or topological insulators. An early version of this methodology has been very successfully applied and extrapolated to Si, Be, BeH, CdSe, MgH, crystals and nanocrystals, with almost chemical accuracy in most cases. Here, after a pedagogical and critical review of the earlier results, we introduce a new combined and expanded approach to comparatively describe the electronic and cohesive properties of diamond and graphene. For the later a drastically enlarged sequence of “nanocrystals” of well-chosen geometries and sizes up to 1440 atoms or 8190 electrons is used to verify earlier predictions and results. We have obtained in a simple and fast way the bandgap (5.4 eV) and the cohesive energy (7.34 eV/atom) of diamond with almost chemical accuracy; and we have fully rationalized (in a different perspective and prospective) the electronic and cohesive properties of graphene, with a tentative value of cohesive energy of 7.52 eV/atom. Strangely enough this value is larger than the one for diamond and is currently under investigation. Finally, we suggest that this methodology in its current simple and transparent form can be a first-line diagnostic, functional, and inexpensive computational tool. This is particularly true for quick assessments and comparative estimates, size-dependence studies, or cases where standard k-space methods or other advanced techniques either fail or demand unavailable computational resources.
Computational Materials and Modelling
Arghadeep Laskar; Prashant Motwani; Shruti Dhruw
Abstract
This work is a vital step in enhancing the potential use of a newly developed organic basalt fibre reinforced polymer (BFRP) bars for prestressed concrete applications. In the present study, a test setup has been designed using finite element analysis (FEA) and the various steps of prestressing such ...
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This work is a vital step in enhancing the potential use of a newly developed organic basalt fibre reinforced polymer (BFRP) bars for prestressed concrete applications. In the present study, a test setup has been designed using finite element analysis (FEA) and the various steps of prestressing such as initial prestress, effective prestress and the time dependent effects have been appropriately simulated in the finite element (FE) model. The configuration details of the test setup, such as the size and orientation of the sections and the location of the stiffener plates have been thoroughly investigated. A robust design of the setup has been established based on the FEA results. Subsequently, the FE model has been utilized to predict the transfer stage parameters for concrete beams prestressed using BFRP bars.The transfer length has been predicted from the FEA results to be 24db and 26db (where, db is the diameter of bar) when measured using the BFRP bar strains and the concrete strains, respectively. An end slip of 0.3mm has been obtained after the prestressing of concrete beams. The designed test setup will be later fabricated and utilized to perform experiments under laboratory-controlled conditions.
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