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Temperature-dependent Multi Scale Large Deformation Simulation of Heterogeneous Crystals

Gordan, Ali | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 50116 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Khoei, Amir Reza; Jahanshahi, Mohsen
  7. Abstract:
  8. In this study, a novel and unprecedented multi-scale hierarchical molecular dynamics (MD) – finite element (FE) coupling method is proposed to demonstrate the influence of temperature on mechanical properties of heterogeneous Nano-crystalline structures. The embedded-atom method (EAM) many-body interatomic potential is implemented to consider pairwise interactions between atoms in the metallic alloys with face-centered-cubic (FCC) lattice structure at different temperatures. In addition, the Nose-Hoover thermostat is employed to adjust the fluctuation of temperature. In order to calculate the equivalent lattice parameter, a weight average between the lattice parameters of atomic structures is utilized. The atomic nonlinear elastic parameters are obtained via computing second-order derivative of Representative atom’s energy and RVE’s strain energy density with respect to deformation criterions (deformation gradient and Green strain tensor). Then, the variations of yield stress points and elastic constants are presented for crystal Cu RVE at different concentrations levels of Ag impurities and at various temperatures. To bridge between atomistic and continuum level, the mechanical characteristics are captured in the atomistic level and transferred to the continuum level directly by functions of strains. Furthermore, comparing the numerical results of the present multi-scale method with MD simulation results, discloses that the suggested techniques produce promising results with small amount of error in large deformation, comparing the numerical results of the present multi-scale method with MD simulation results, discloses that the suggested technique produces promising results for evaluating the temperature effects on problems including heterogeneous Nano-crystalline structures
  9. Keywords:
  10. Large Deformation ; Multiscale Hierarchical Analysis ; Molecular Dynamics ; Finite Element Method ; Representative Volume Element ; Heterogeneous Nanocrystaline Structure ; Temperature Dependent Properties

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