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Simulation of Thermal Barrier Coatings under Thermo-Mechanical and Low Cycle Fatigue Loadings

Rezvani Rad, Milad | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45415 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Farrahi, Gholamhossein
  7. Abstract:
  8. The main purpose in this thesis is the finite element simulation of thermal barrier coatings (TBC), subjected to residual stresses due to the coating process followed by thermo-mechanical fatigue loadings. This finite element modeling is performed in the ABAQUS software. In order to consider the actual condition of thermal barrier coating, models are defined based on a SEM image including real roughness and porosity of coating layers using image processing technique.
    Two-step residual stress taking into account both coating process of bond coat and top coat layer is performed. Pre- heating of substrate and bond coat in order to reach comperessive stresses in coating layers has been taken into consideration. Afterwards, in order to simulate the real nature of loadings in a diesel engine cylinder head, models are subjected to out of phase thermo-mechanical loadings. Finally, the results that have been acquired by simulation of partial models under thermomechanical loadings are compared to the results taken from experimental tests. It is worth mentioning that the difference between results acquired by thermo-mechanical stress experiment and its simulation is only 18.9%.
    In the end, a cylinder head example in ABAQUS software has been used to simulate TBC in the real working condition. Residual stress and thermomechanical simulation have been performed. Finally, optimized thickness of TBC was presented
  9. Keywords:
  10. Thermal Barrier Coating ; Aluminum-Magnesium-Silicon Alloy ; Finite Element Simulation ; Thermomechanical Stress Analysis ; Two Step Residual Stresses

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