Optimal Design of Tolerances in the Non-rigid Assemblies under the Thermal Impact

Hemati Nik, Javad | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48694 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Khodaygan, Saeed
  7. Abstract:
  8. Tolerance allocation in the recent mechanical assembly is significant because it straightly affects product performance and cost. Loose tolerances may cause the quality defect while tight tolerances can increase the cost. Thermal effects and the temperature gradients are one of the factors that caused changes in the size and geometry of the components during the performance of mechanical assemblies. This thesis proposes a new approach for tolerance design considering the thermal effects, to achieve lower manufacturing cost and good product quality. Finite element analysis is used to determine the deformation of components in an assembly. The neural network is trained using experimental results from FEM to develop assembly function. According to the approach, the optimized tolerances are determined in the form of a multi-objective problem, as the aim is to minimize total manufacturing cost and quality loss function and improve assembly's performance. Cost function is developed based on the experimental results with response surface methods and also Genetic algorithm (NSGA ΙΙ) is followed for optimizing tolerance allocation problems. Finally, two case study under various temperature conditions is given to verify the proposed approach. The results prove that there is a considerable change in cost and performance
  9. Keywords:
  10. Tolerance Allocation ; Neural Network ; Finite Element Analysis ; Thermal Effect ; Multiobjective Optimization ; Geometrical Tolerance ; Dimensional Tolerance ; Non-Dominate Sorting Genetic Algorithm (NSGAII) Method ; Non-Rigid Mechanical Assemblies

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