Master's Theses

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    Development of novel methodologies for rotational dynamics applications
    (2020-12-31) Abbasi, Ahmad; Şendur, Polat; Şendur, Polat; Poyrazoğlu, Göktürk; Tunç, B.; Department of Mechanical Engineering; Abbasi, Ahmad
    In this thesis, a novel methodology is proposed to determine the parameters of a rotating unbalance in a rotor-bearing system. For that purpose, the weighted sum of squared difference between the analytical and predicted unbalance response due to rotational unbalance, is considered as the objective function. A hybrid algorithm integrating Salp Swarm algorithm (SSA) and Nelder–Mead algorithms (NM) is presented for detecting unbalance magnitude and phase as the unbalance parameters. Parameters of the aforementioned optimization algorithm are determined systematically using the Taguchi design of experiments method. The efficiency of the proposed method is compared with various optimization algorithms in the literature. To account for the variability and to mimic the actual experiment conditions, noise with different levels is added to the simulation results. The results show the superiority of the proposed hybrid algorithm (SSA-NM) in terms of the accuracy of the unbalance parameters and computational efficiency. In the last part of this thesis, application of metaheuristic algorithm optimization on two engineering problem examined. The first one is related to maximization of fatigue life of Tapered Roller Bearing (TRB). In second one, the performance and efficiency of Microchannel Heat Sink (MCHS) is improved by Harris Hawks optimization algorithm. In this problem, the entropy generation of MCHS is formulated as objective function for the optimization problem and the Harris Hawks try to minimize the entropy generation, which is undesirable factor for MCHS. Also, several fluids as coolant are considered for the MCHS that the ammonia has best performance in comparison to the others.