Loading...

Coarse Grained-Atomistic Concurrent Multi-Scale Modeling for Numerical Simulation of Mechanical Behavior of Heterogeneous Materials in Nano-cale

Ali Madadi Ahmadabadi, Ashkan | 2020

385 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52902 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. In this thesis, a method has been exploited to couple the atomistic domain with the coarse-grained domain. Since molecular dynamics has a high computational cost when a large number of atoms exist, coarse-grained molecular dynamics was used in which a number of atoms are assumed as a bigger bid and interatomic potential is modified for bids so that the material’s mechanical properties remain constant. This method not only reduces the computational cost of calculating forces in molecular dynamics simulation but also, the time step used in Coarse-Grained Methods can be more than atomistic simulations as the frequency of occurring phenomena in CG scale is less than atomistic scale.The advantage of using coarse-grained simulations is that these methods are based on molecular dynamics equations and does not need constitutive laws that are exploited in continuum mechanics. Determining constitutive law in nano scale is very complex.When using coarse-graining method, not only does this method fail to model defects and heterogeneity in material, but also it is not able to model phenomena with a smaller wavelength in comparison to coarse grain lattice spacing. Therefore, critical regions of a domain are modeled by molecular dynamics and other parts by coarse-grained. In one problem, fourier transform was exploited to resolve the issue of high-frequency wave reflection in the interface of coarse and fine scales.Dislocations play a crucial role in determining the mechanical behavior of superalloys even though a considerable number of atoms are located in perfect lattice-structures and dislocations comprise a small region of the domain. Thus, it is rational to use the abovementioned method in modeling these materials. misfit dislocation evolution in the interface of Ni_3 Al and Ni ,which is formed by their subtle difference in lattice parameter, has been modeled in this study
  9. Keywords:
  10. Molecular Dynamics ; Superalloys ; Dislocation ; Multiscale Modeling ; Simulation ; Coarse Grained Model ; Coarse Grain Molecular Dynamic

 Digital Object List

 Bookmark

No TOC