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    Robust Design Optimization for Fatigue Life with Geometric and Material Uncertainties of Mechanical Parts Under Random Loading Based on Maximizing Fatigue Life and Minimizing Uncertainty in Fatigue Llife Prediction

    , M.Sc. Thesis Sharif University of Technology Esfahani, Saeed (Author) ; Khodaygan, Saeed (Supervisor)
    Fatigue life prediction of a mechanical part is one of issues which a group of engineers are engaged with it and always they try to design the parts with the maximum of lifetime. Although many researches have been done in this field but yet we can see that predicted life are different from that happens in the reality because there are some uncertainties in the phenomena. Our effort in this project is creating an algorithm design so that the parts are designed by it, have the maximum fatigue life and the minimum uncertainty in prediction. In this project we have considered geometrical, material and random loading uncertainties as error resources. Older methods those are presented in this... 

    Fretting Fatigue Crack Initiation Life Prediction Model in a Dovetail Joint of a Compressor

    , Ph.D. Dissertation Sharif University of Technology Badrikouhi, Ehsan (Author) ; Adibnazari, Saeed (Supervisor)
    Fretting fatigue is one of the main factors leading to failure in structures that have components temporarily connected to each other. The occurrence of fretting at the connection region of a structure under cyclic loading is inevitable, and only various methods can delay its occurrence or minimize the damage resulting from it. Fretting is dependent on various factors, and this has made previous studies unable to lead to a unified approach for predicting the fretting fatigue crack initiation life. In this thesis, after reviewing previous studies, a proving ring is designed for fretting fatigue testing. In the next step, fretting fatigue tests using the bridge-type method are performed on... 

    Predicting the Fatigue Life of Repaired Specimens by Composite Patch Exposed to Corrosive Environments Using Artificial Neural Network and Finite Element Method

    , M.Sc. Thesis Sharif University of Technology Bakhshiyan, Amir Hossein (Author) ; Farrahi, Gholamhossein (Supervisor)
    In this research, the application of composite patch in the repair of pipes damaged by corrosion has been investigated. Numerical modeling, artificial neural network and Taguchi algorithm are used for this purpose. In the numerical modeling section, the accuracy of modeling performance has been verified by experimental results of other researchers. Then, the effect of various parameters such as depth and, angle of corroded area, fiber orientation in the composite patch and angle of composite patch have been investigated. The depth and the angle of the corroded area and the angle of orientation of the fiber have been shown to have a large effect on the growth life of fatigue cracks. For...