Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Artem, Hatice SeçilSubject: search.filters.subject.Mechanical Engineering

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Now showing 1 - 4 of 4
  • Master Thesis
    Lazer Toz Yataklı Füzyon Yöntemiyle Üretilen Ti-6Al-4V Alaşımının Süreç Parametrelerinin Stokastik Arama Yöntemleri Kullanılarak Optimizasyonu
    (2025) Aktunalı, Mehmet; Artem, Hatice Seçil
    Eklemeli imalat, karmaşık geometrilerin yüksek hassasiyetle üretilebilmesine olanak sağlaması nedeniyle çeşitli sektörlerde yaygın olarak kullanılan bir üretim yöntemi haline gelmiştir. Ti-6Al-4V alaşımı, üstün mekanik özellikleri ve iyi biyouyumluluğu sayesinde eklemeli imalat uygulamalarında oldukça tercih edilmektedir. Eklemeli imalat ile üretilen Ti-6Al-4V bileşenlerin mekanik, fiziksel ve yüzey özellikleri; lazer gücü (P) ve tarama hızı (V) gibi proses parametrelerinden önemli ölçüde etkilenmektedir. Bu çalışma, yüksek Vickers sertliği, düşük Arşimet porozitesi ve düşük yüzey pürüzlülüğü elde etmek amacıyla, Ti-6Al-4V alaşımının Laser Powder Bed Fusion (LPBF) yöntemiyle üretiminde P ve V parametrelerinin optimizasyonunu incelemektedir. Literatürde mevcut olan deneysel veriler kullanılarak, proses-çıktı ilişkileri, regresyon analizi ile yapay sinir ağı yöntemlerinin güçlü yönlerini bir araya getiren hibrit bir modelleme yöntemi olan nöro-regresyon yaklaşımı ile modellenmiştir. LPBF yöntemiyle üretilen Ti-6Al-4V alaşımında yüksek sertlik, düşük porozite ve kontrollü yüzey pürüzlülüğü elde etmek amacıyla farklı P ve V proses parametre koşulları için çeşitli optimizasyon senaryoları tasarlanmıştır. Bu senaryolar, 'Wolfram Mathematica 13' programında yer alan 'NMaximize' ve 'NMinimize' araçları kullanılarak, Differential Evolution, Nelder-Mead, Simulated Annealing ve Random Search gibi farklı stokastik optimizasyon algoritmaları ile optimize edilmiştir. Elde edilen optimizasyon sonuçları literatür ile karşılaştırıldığında, kullanılan modelleme ve optimizasyon yöntemlerinin güvenilirliğini ve uygulanabilirliğini göstermektedir ve çalışma, biyomedikal ve havacılık uygulamalarında yüksek performanslı parça üretimine katkıda bulunma potansiyeline sahiptir.
  • Master Thesis
    Experimental Analysis and Modeling of Shear Strength of Adhesive-Bonded Single-Lap Glass Fiber Reinforced Composites
    (01. Izmir Institute of Technology, 2024) Artem, Hatice Seçil; Serbest, Sertaç; Artem, Hatice Seçil
    Composite materials are being used in many fields of industry day by day. With this increasing interest in composites, the methods of joining composites have also become the focus of attention. Mechanical fasteners cause damage to the composite, increase in weight, and stress accumulation in the joint area. Recently, joining composites with adhesives has attracted the attention of researchers. In this study, glass fiber reinforced polymer composites were combined with two paste adhesive thicknesses, using two brands of paste adhesives as fast-curing and slow curing, and three different peel plies and the effects of these three different parameters on the bonding strength were investigated both experimental and numerical analyses. In the experimental part of the thesis, glass fiber reinforced polymer composites were produced by the vacuum infusion method. The surfaces modified with different peel plies were combined with two different paste adhesives. A single-impact shear test was performed to examine the bond strength. As a result, it was observed that the fast-curing paste adhesive showed better performance in bond strength. At the same time, it has been experimentally demonstrated that the paste adhesive thickness of 0.6 mm has a positive effect compared to the paste adhesive with a thickness of 0.4 mm. It has been observed that the different peel plies used did not make a critical difference in the bond strength. In the numerical part of the thesis, six different regression models were used to model the shear strength of adhesive-bonded composites and then an optimization study was carried out by selecting the two best regression models that accurately express the physical model. Using the stochastic optimization methods, Differential Evolution and Nelder Mead algorithms, the optimum shear strength values possible with the existing parameters were found. This thesis contributes to determination of the bonded samples with the highest shear stress value by determining the optimum parameters.
  • Master Thesis
    Optimization of Injection Molding Process Parameters for Cycle Time
    (01. Izmir Institute of Technology, 2024) Kaplan, Anıl; Artem, Hatice Seçil
    Plastic, an integral part of modern life, is widely used in various sectors such as automotive, aerospace, and healthcare. The rapid advancements in the plastic industry have improved plastic processing technologies. Among contemporary production methods, plastic injection molding has become one of the most commonly used techniques. As industrial markets evolve rapidly, the need to shorten product cycle times, reduce production costs, and increase production speeds to respond swiftly to demand has become increasingly urgent. In this context, the thesis addresses the reduction of cycle times through the optimization of process parameters in the injection molding process. By utilizing experimental data available in the literature, a mathematical model of the injection molding process has been developed using a hybrid method known as Neuro-regression approach and cross-validation technique. To minimize the cycle time of the injection molding process, multi-objective optimization scenarios were created using seven different process parameters and two parameters affecting product quality. Optimization studies were carried out using stochastic optimization methods with the 'Simulated Annealing,' 'Random Search,' 'Nelder-Mead,' and 'Differential Evolution' algorithms in the 'Wolfram Mathematica' program with the help of the 'NMinimize' tool. When comparing the obtained optimization results with those in the literature, it was found that the model and optimization methods used in the study are reliable and applicable.
  • Master Thesis
    Design and Optimization of Hydraulic Actuator Used in Jet Fighter
    (01. Izmir Institute of Technology, 2024) Denizci, Ahmet; Artem, Hatice Seçil
    Actuators have been used in many areas from past to present. It is an indispensable equipment in the areas of use in today's technology. They are classified according to their usage areas and drive type. Depending on the type of drive, there are hydraulic, pneumatic and electrical actuators. It also has many uses: construction, manufacturing, automotive, robotics and aerospace industries. Hydraulic actuators are frequently used equipment in the aviation industry. In this thesis, the hydraulic actuator rod used in jet fighters was examined. This actuator is used to move the flight control surfaces in the jet fighter. So hydraulic actuator is vital for jet fighters. First, by conducting a literature search, boundary conditions and parameters were determined for actuator design and analysis. The design of rod was made using the determined parameters and the design parameters were analyzed using the finite element method. Neuro-regression approach was used to model a compact, lightweight and durable actuator. After regression analysis, many scenarios were created to optimize the mass and von Mises stress of the rod. The design and optimization of the hydraulic actuator rod were achieved by using Differential Evolution, Nelder-Mead, Random Search and Simulated Annealing algorithms. It has been concluded that the model and optimization algorithms are reliable and applicable to the problem.