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Farshid, Saman | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43028 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Adib Nazari, Saeed
  7. Abstract:
  8. First stage blades tempreture in the turbine rotor section for the advanced turbines has increased up to 1100oc. The blades should be under mentioned condition for the long times up to 70000 hours and accordingly creep happens. Fatigue–creep interaction is the main reason for the failures of many engineering components under high temperature and cyclic loading. In this thesis, a model for the life prediction of fatigue–creep interaction which was developed by other investigators has been modified to predict fatigue–creep interaction on the nickel-based superalloys. In this model, the law of energy conservation and the momentum conservation principle are used to describe the process of fatigue–creep interaction.¬¬ By some mathematical techniques, the constants of new model was obtained for Rene 95 at 650oc. To check the validity of the new model for nickel-based superalloys, this model was compared to three models such as strain range partition , frequency separation , ostergren model for Rene 95 at 650oc. By comparsion obtained results has been observed that new model is most accuracy model for life prediction Fatigue–creep interaction of the nickel-based superalloys and good agreement has been achieved between the predicted lives and the experimental result
  9. Keywords:
  10. Nickel-Base Superalloy ; Life Time Estmation ; Energy Conservation ; Creep-fatigue Interaction ; Inelastic Strain Range ; Mechanical Work ; Momentum Conservation

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