Loading...

Multi-Scale Simulation of Metallic Nano-Alloy Compression Process Using Plasticity Cone-Cap Behavior Model

Ashtari, Mehrdad | 2021

246 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54312 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. The primary purpose of this study is to perform nonlinear behavior simulations in the compaction and forming of metal powders and their alloys and investigate their behavior in the plastic state. Powder compression is one of the methods of producing metal parts with high precision and improved mechanical properties, which is why it has been considered in addition to its need in the industry.There are various methods for performing these simulations, including multi-scale methods with optimal performance. Given that only the use of high-scale methods or only low-scale methods will have problems and disadvantages in such simulations, multi-scale methods will be a good alternative in which both scales are used optimally. This method is based on transferring information from one scale to another. One of the low-scale methods is the molecular dynamics method, which is in atomic-scale methods. This method, due to the study of phenomena at the atomic scale and considering the behavior of atoms and their interaction with each other using inter-atomic potential, their accuracy is high in studying phenomena in the behavior of materials, such as fracture or dislocation phenomena in which their study according to behavioral complexity makes simulation difficult. However, on the other hand, it has a high computational cost. So that only the simulation of small samples of several hundred thousand atoms, in terms of computational cost, using modern systems, is reasonable. Therefore, by analyzing this behavior in small samples at the atomic scale and using the results at high scales, we can take advantage of its high accuracy in investigating the mechanical properties of materials and the advantage of low computational cost and perform high-scale simulations on a larger size. In fact, in this multi-scale method, the effect of boundary conditions and the complex geometry of the parts and their mechanical properties can be modeled. Due to the point that the powder compaction method is used to make various industrial parts with complex geometries and performing this process in the industry has a high cost, this method is beneficial for determining the properties and characteristics of the desired process and by performing simulations, their performance in the industry can be optimized. The large-scale method used in this research is the finite element method used to solve problems with different sizes. By enriching the equations governing plasticity relations by using mechanical properties obtained from the atomic scale, this method can solve large size industrial problems with different boundary conditions to compact and form the powder. The properties obtained from the nano-scale affect the obtained parameters of the plasticity behavior model. After that, atomic simulation is no longer needed, and the macro-scale, independent of the nano-scale, is used in the solution; thus, the volume of calculations is significantly reduced. Finally, some numerical examples will be solved using the obtained Cone-Cap plasticity behavior model to present its performance
  9. Keywords:
  10. Powder Compaction ; Plasticity ; Molecular Dynamics ; Finite Element Method ; Multi-Scale Simulation ; Powder Forming ; Metallic Nano Alloys

 Digital Object List

 Bookmark

No TOC