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Temperature-dependent Multiscale Simulation of Heterogeneous FCC Crystals

Jafarian, Navid | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 48275 (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 multiscale hierarchical molecular dynamics (MD) – finite element (FE) coupling method is proposed to illustrate 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 surfaces and curves of strain energy density are attained via fitting a fourth-order polynomial function to quantities of strain energy density corresponding to representative volume elements (RVE’s) subjected to biaxial and shear deformation loadings. The atomic linear elastic parameters are obtained via computing second-order derivative of surfaces and curves of strain energy density with respect to strain. Then, the variations of yield stress points, elastic constants, and bulk modulus (B) are presented for crystal Cu RVE at different concentrations levels of Al impurities and at various temperatures. To bridge between atomistic (nano-scale) level and continuum (macro-scale) level, the mechanical characteristics are captured in the atomistic level and transferred to the continuum level based on hyperelasticity theory. Furthermore, comparing the numerical results of the present multiscale 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. Finite Element Method ; Molecular Dynamics ; Mechanical Behavior ; Representative Volume Element ; Face Centered Cubic (FCC)Alloy ; Heterogeneous Nanostructures ; Temperature Related Hierarchial Multiscale Model ; Temperature Dependent Thermophysical Properties

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