Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Optimization of Buckling Behavior of Hybrid Composite Beam Under Axial Compression(01. Izmir Institute of Technology, 2021) Altıntaş, Hayri; Artem, Hatice Seçil; Artem, Hatice Seçil; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe use of lighter and high-performance materials in the aerospace sector is of great importance. Optimization methods, which have become very popular with the technological development in the production methods of composite structures in recent years and provide the most suitable design for the purpose, are frequently preferred in the design of parts in the aviation industry. Determining the buckling load capacity of a composite beam under compression load is very important for the design of composite structures. The buckling load capacity of a hybrid composite beam with fiber metal laminate (FML), which is frequently used between aircraft wing and fuselage. The optimum design of the anti-buckling behavior of the hybrid composite beam, which is subjected to compression load, fixed by simple support on both sides, was performed by a genetic algorithm (GA) based on the Tsai-Wu fracture criterion. The robust design of composite hybrid laminates was developed using a design optimization process based on GA with the finite element method. A multi-objective genetic algorithm (MOGA) was used to optimize the design of a hybrid composite beam subjected to buckling. Design variables in the optimization process are considered as fiber material and angle orientations. The purpose of the objective function is to reduce the equivalent stress of hybrid composites while increasing critical buckling load. The design constraint was the Tsai-Wu failure index. As a result, it has been observed that the buckling performance of the beam depends on the structure of the metal material in FML composites. Carbon/epoxy and glass/epoxy structures were proposed and a design was aimed according to the maximum buckling load in the best stacking sequence, taking into account the data in the design constraints.Master Thesis Investigation of Mechanical Properties and Fatigue Performance of Carbon-Glass Fiber Reinforced Epxy Hybrid Composites(Izmir Institute of Technology, 2019) Sandallı, Hatice; Tanoğlu, Metin; Tanoğlu, Metin; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRecently, hybrid composites have known as high performance engineering materials and they have been used broadly in engineering applications where high strength to weight ratio, reasonable cost and ease of fabrication are requested. Since these composites offer combination of benefits of different kinds of fibers, their usage is increasing day after day. The objective of this thesis is to examine the mechanical properties of carbonglass fiber reinforced epoxy hybrid composites in two different configurations. Also, the fatigue performance under bending tests of these composites were investigated. The hybrid composites were manufactured by using vacuum infusion technique at ambient temperature. To examine the mechanical properties of manufactured composites, a series of mechanical tests such as compression, tensile and three-point bending tests were performed on the samples which were prepared in accordance with the relevant ASTM standards. Load-controlled three-point bending fatigue tests were also carried out to investigate the performance of manufactured composites under fatigue. The fatigue tests were performed at different stress levels varied from 30 percent to 90 percent of average ultimate flexural strength of the samples which were determined from static three-point bending tests. Subsequently stiffness loss and Wöhler curves were constructed using a specific failure criterion.