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https://hdl.handle.net/20.500.12846/804

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  • [ X ]
    Öğe
    Investigation of weld quality for friction stir welding of extruded 6000 series aluminum alloys
    (Türk-Alman Üniversitesi, 2019) Keskin, Ezgi Yağmur; İpekoğlu, Mehmet
    Kaynak, endüstrilerde sıkça uygulanan bir birleştirme tekniğidir; ancak, çoğunlukla uygulanan ergitme kaynağı, alüminyum alaşımlarına uygulandığında problemlere ve kaynak kalitesinin olumsuz etkilenmesine sebep olabilmektedir. Sürtünme karıştırma kaynağı, diğer birleştirme yöntemleri arasında birçok avantaj sağlayan bir birleştirme tekniğidir. Bu yöntem, alüminyum alaşımlarının ve farklı metallerin birleştirilmesini başarıyla gerçekleştirir. Bu çalışmada, 6000 serisi alüminyum alaşımlarının kaynak davranışları, ekstrüzyon ürünü AA 6005-T6 ve AA 6082-T6 alaşımlarının sürtünme karıştırma kaynak işlemi ile birleştirilmesiyle incelenmiştir. Toplamda, üç farklı set, test planına dahil edilmiştir: AA 6082-T6 ile AA 6082-T6'nın kaynağı, AA 6005-T6 ile AA 6005-T6'nın kaynağı ve AA 6005-T6 ile AA 6082-T6'nın kaynağı. Kaynak prosesi vidalı konik pinli sürtünme karıştırma takımı ile kaynağa adapte edilmiş 5 eksenli CNC tezgahında gerçekleştirilmiştir. Çalışmanın ana parametreleri takım devri ve kaynak hızı olarak belirlenmiştir. Kaynak kalitesi, çekme testi, mikro sertlik testi, mikroskobik ve makroskobik analizler dahil olmak üzere çeşitli testlerle incelenmiştir. Kaynak parametrelerinin kaynak kalitesi üzerine etkisi incelenmiştir.
  • Küçük Resim
    Öğe
    Advanced mechanical and microstructural characterization of rear bumper material produced from hosehold waste
    (Türk-Alman Üniversitesi Fen Bilimler Enstitüsü, 2023) Kara, Gizem; Elibol, Çağatay
    In this study, the usability of the composite material, which is the result of adding an organic decarbonizer to the talc reinforced polypropylene matrix, as a rear bumper in passenger buses, is investigated. In this context, it is aimed to obtain a cheap, sustainable and environmentally friendly composite. The mentioned organic decarbonizer is created from unsorted household waste and its average carbon footprint is -11.7 kg/CO2eq. The carbon footprint of polypropylene, which is used as a matrix material, is 2.8 kg/CO2eq. Four observation groups were formed based on the results of life cycle analyzes and carbon footprint contributions. These groups are respectively 10% decarbonizer + 20% talc, 20% decarbonizer +15% talc, 25% decarbonizer + 12% talc and 37% decarbonizer + 10% talc. In order to evaluate its usability as a rear bumper in passenger buses, advanced mechanical characterization and microstructural examination of the observation groups were carried out. In order to observe the performance decrease that may occur due to temperature over time, the same experiments were repeated on the samples that underwent accelerated thermal aging at 100 ?C for 7 days. In the results obtained, it was seen that the decarbonizer behaves in a fibrous structure inside the material, but is not surrounded by the matrix. At the same time, it was seen that the distribution of the decarbonizer material in the matrix was random and did not have any orientation. It has been determined that as the ratio of decarbonizer increases, the matrix-decarbonizer interaction, which weakens the material by creating stress concentration areas in the material, increases and this situation deteriorates the mechanical properties of the material. In the tensile tests, impact tests and bending tests, it was observed that the strength and toughness of the material decreased as the decarbonizer ratio in the material increased and the talc ratio decreased, as well as the ductility of the material. As a result of thermal aging, a 1% decrease was observed in tensile strength in all observation groups, while an increase between 3% and 12% was observed in elongation at break. In the impact tests, a decrease of up to 18% was observed in the impact strength of the samples subjected to thermal aging. In the observation group containing 25% decarbonizer and 12% talc, results were obtained that do not comply with the trend of deterioration of mechanical properties due to the increasing decarbonizer ratio in the material in impact strength and flexural strength. The reason for this behavior has not been determined yet, and this issue will be emphasized in the next study.