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Coarse-gained Multi-scale Modeling for Numerical Simulation of Nonlinear Behavior of Materials in Nano-scale

Mohammadi, Khashayar | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51933 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. In this thesis, a coarse-grained multi-scale method for 2D crystallyn solids based-on finite element consepts has presented. In this method, both scales are atomic scale and similar to what we see in non-local QC method, the entire atomic structure will be intact. Accordingly, calculations of potential functions and forces in the domain will have the atomic accuracy. In the presented method to reduce the domain’s degrees of freedom, the classical finite-element meshing concept to mesh the elastic linear areas in the domain is used and the MD calculations will done on the mesh nodes. Therefore, degrees of freedom in the system will reduce and consequently, the computational cost will reduce. Parts of the domain that need the atomic-scale accuracy to investigate the phenomena such as crack propagation and dislocation analysis, the mesh will be finer as far as a mesh consist of three atoms on nods without any inner atoms. The advantages of using this method include (1) Besides the reduction in degrees of freedom the entire atomic structure completely preserved. (2) The potential functions that is used in this method is exactly the same as MD potential functions and there is no need to create a new potential function for this method. (3) Whenever there is a need for atomic precision for simulations, the atomic structure is reachable without any unmapping or other method because the atomc structure remains intact. (4) This method has the ability to simulate the alloy structures and heterogeneous domains consisting two or more materials. (5) This method has the ability to increase the accuracy to reach the all-atom accuracy. This requires using a sutitable adaptive mesh refinement in the domain. Due to the impressive reduction in domain’s degrees of freedom in linear and elastic parts of the domain, this method can simulate the larg envirenments. To examine the capabilities of the presented method several simulations is presented in this thesis
  9. Keywords:
  10. Molecular Dynamics ; Multiscale Modeling ; Coarse Grained Model ; Atomic Simulation ; Metals Simulation ; Alloys Simulation ; Nano-Scale Modeling

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