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A Novel Atomistic Modeling Technique for Poly-crystalline Nanoporous Metals



In this study, a novel technique, which is mainly based on the Voronoi tessellation method representing randomly oriented three-dimensional network of ligaments for the atomistic modeling of poly-crystalline nanoporous metals, is presented. In this regard, by the utilization of the proposed methodology atomistic models of polycrystalline nanoporous metals consisting of randomly oriented ligaments with nonuniform mass distribution along the ligament axis can be generated, which in turn enables researchers to control both length and diameter of the individual ligaments within the porous network. Furthermore, the atomistic models of poly-crystalline nanoporous materials can be simply employed for the mechanical, thermal and acoustic characterization through molecular dynamics (MD) simulations. In general, proposed modeling technique consists of five steps. In the first step, a modeling process, which has been already used in literature for the modeling of poly-crystalline bulk metals, is followed. In this step, Voronoi tessellation technique is utilized for the purpose of generating the granular structure. In the second step, in order to define the volumetric region for the ligaments of the nanoporous structure, the process for the generation of a new Voronoi tessellation is initiated. In the following step, the coordinates of randomly distributed points are determined in a controlled way to be employed in the establishment of the Voronoi tessellation, which results in randomly oriented and intersected line segments. Then, the line segment representation of the Voronoi tessellation is transformed into a unique volumetric region by using spherical regions. Finally, the atoms external to the volumetric region are removed from the poly-crystalline bulk metal resulting in a poly-crystalline nanoporous structure. In conclusion, the ultimate goal of the study is to generate atomic coordinates that can be employed for the MD simulations of randomly organized poly-crystalline nanoporous structures. Furthermore, the thermodynamic stability of poly-crystalline nanoporous metal is also investigated to validate the feasibility of the atomistic model.


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