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Selection of the Optimal Orientation of Parts in Rapid Prototyping Processes

Amir Hossein Golmohammadi | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50107 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Khodaygan, Saeed
  7. Abstract:
  8. Additive manufacturing (AM), also known as Rapid prototyping or D printing, is a new technology for the manufacturing of the physical parts through an additive manner. In the AM process, the orientation pattern of the part is one of the most important factors that significantly affects the product properties such as the build time, the surface roughness, the mechanical strength, the wrinkling, and the amount of support material. The build time and the surface roughness are the more imperative criteria than others that can be considered to find the optimum orientation of parts. In this research, Two method is used to optimize part build orientation (PBO). In the first method a new combined meta-modeling/NSGA II/TOPSIS method is introduced to find the accurate optimal PBO in the AM based on the multi-criteria optimization formulation. In order to reach this aim, first, a new formulation is proposed to model the build time with respect to the PBO in AM processes. Then, a proper formulation is developed to estimate the mean surface roughness based on the part orientations. Then by utilizing Kriging method as a powerful metamodeling approach, the build time and the surface roughness as the objective functions are modeled in the explicit form in terms of the part orientation. Then, the non-dominated sorting genetic algorithm II (NSGA-II) is used for solving the multi-criteria optimization problem that its objectives are the build time and the surface roughness. In the following, a set of Pareto-optimal solutions is obtained from the optimization problem solving. The TOPSIS method is employed to rank all obtained optimal solutions for selecting the best solution. Second method proposes a multiplex method to determine optimum part build orientation by using new developed Taguchi design of experiments in multi objective optimization problem to minimize build time and the surface roughness. Then by using Taguchi's orthogonal arrays and Design of experiments method optimum part build orientation is determined. Finally, case studeis is provided to illustrate and validate the accuracy and efficiency of the proposed method. The proposed approach aims to precisely find the optimal PBO for the several AM processes under the low computational time. Finally, a case study is provided to demonstrate and validate the efficiency and accuracy of the proposed method
  9. Keywords:
  10. Rapid Prototyping ; Genetic Algorithm ; Taguchi Method ; Kriging Metamodel ; Design of Experiments Method(DOE) ; Standard Triangular Language (STL) ; Build Time Estimation ; Optimum Part Build Orientation

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