Investigating Effect of Nano Ceramic Coating of Combustion Chamber on the Performance of Internal Combustion Engines

Sharifi, Masoud | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46334 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Naghdabadi, Reza
  7. Abstract:
  8. Thermal barrier coatings (TBCs) are used for increasing the efficiency and reducing pollutants of internal combustion engines (ICEs). In this paper, an optimization framework is developed in order to obtain the optimal dimensions for conventional coat, and the optimal dimensions and material property for functionally graded (FG) coat of a partially coated piston. A thermo mechanical analysis is investigated for Nano coat by finite element method. The conventional and Nano coats are made of MgZrO_3 as the insulating ceramic overlay and NiCrAl as the metallic bond-coat. The properties of the FG coat is assumed to vary according to power law through the thickness. For all tree conventional, FG and Nano coats, it is observed that shear stress increases by increasing the thickness of the coating but normal stress decreases. Also, it is found that shear and normal stresses are mostly governed by the thickness, rather than the width, of the coating. The cost function is a linear combination of nondimensional normal stress, shear stress, and the volume of the coating multiplied by weight coefficients. In each iteration of optimization procedure, the cost function is evaluated by solving an uncoupled thermo-mechanical scheme with finite element method. Optimization problem is solved for two cases of cost function: considering the volume of the coating, and neglecting it. In order to model thermo-mechanical behavior of Nano structured coating, molecular dynamics (MD) is employed. Hence, results of MD are obtained for a representative volume element in simple and multi-axial extension, afterward, some hyper-elastic models (e.g. Oden, linear elasticity) are calibrated with the purpose of minimizing the error
  9. Keywords:
  10. Optimization ; Thermo-Mechanical Analysis ; Nanostructured Coating ; Thermal Barrier Coating ; Piston ; Finite Element Method ; Functionally Graded Coat (FGC) ; Molecular Dynamics

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