https://hdl.handle.net/20.500.12294/486 Makina Mühendisliği Bölümüne ait makaleler bu koleksiyonda listelenir. 2026-05-22T20:55:25Z https://hdl.handle.net/20.500.12294/4138 Development of sinter linings for high-speed trains Bebekoglu, Sunay; Topuz, Ahmet; Cakir, Esin; Adsoy, Abdulhamit; Yildiran, Turgay In this study, brake linings with Cu (copper)-based and Cu-10Sn (bronze)-based matrix structures have been developed and produced by the powder metallurgy method using sinter metal technology for use in high-speed trains. The developed linings were compared with commercial high-speed train linings. Firstly, the mixing process was carried out in a Turbulo 3V three-dimensional mixer for 4.5 h at 50 rpm. The pressing process was performed at room temperature, under the pressure of 350-450 MPa, and the sintering temperature for Cu-based linings was 1,000 °C, while for Cu-10Sn-based linings, it was 800 °C. After the pressing and sintering processes, lining sample density calculations were conducted, and hardness tests were carried out in the Rockwell L scale. Shear strength tests, friction coefficient, and wear tests were conducted according to SAE J 661 standards. It was observed that sinter metal brake linings with Cu and Cu-10Sn main matrix structures showed similar properties and met the technical requirements. It was determined that the developed production prescriptions are promising for industrial production and patent studies. © 2024 Walter de Gruyter GmbH, Berlin/Boston 2024. 2024-01-01T00:00:00Z https://hdl.handle.net/20.500.12294/4008 Effect of Welding Process Parameters on the Strength of Dissimilar Joints of S355 and Strenx 700 Steels Used in the Manufacture of Agricultural Machinery Szusta, Jaroslaw; Derpenski, Lukasz; Karakas, Oezler; Tuzun, Nail; Dobrzanski, Slawomir The paper evaluates the possibility of using dissimilar materials joined by welding technology in the construction of agricultural machinery. The desire to design larger and more efficient structures requires designers to combine materials with different mechanical and structural properties. In such a case, it is very important to properly select welding parameters so that, on the one hand, the quality of the joint meets the standard requirements, and on the other, the welding process is not too energy-intensive. In this paper, overlay joints connecting S355 steel with Strenx 700 steel were analyzed in terms of strength for three different values of welding parameters and different thicknesses. The starting point was the reference parameters recommended by the company’s welding technologists, which were reduced by 10 and 20% according to the linear welding energy. The study compared the strength, ductility and macrostructure of the joints, as well as the energy intensity of the process. The proposed dissimilar joints achieved approximately a 10% increase in the strength limit of the components in comparison to the previously recommended welding parameters. Additionally, finite element analysis calculations of the improved designs showed significant weight reduction (up to 40%) for the relevant agricultural machinery components. © 2023 by the authors. 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12294/4005 Key implications on food storage in cold chain by energy management perspectives Karacan, M. Akif; Yilmaz, I. Cengiz; Yilmaz, Deniz Over the past decades, increase in food shortages and food costs with the drought caused by population growth and climate change, it becomes more important to prevent food losses with the widespread use of cold storage. That’s why many countries provide incentives for the widespread use of cold stores. However, with cold storages becoming more widespread, keeping energy consumption under control becomes an important issue. Especially in most developing countries, the status and energy performance of installed cold stores are unknown. In this study, energy consumption data were examined by using data from cold stores from different countries. The relationships between some parameters (capacity, volume, etc.) affecting energy consumption were analyzed for 67 established cold stores. In order to measure the energy consumption data of the system under ideal operating conditions, experiments were carried out in the test room under laboratory conditions and comparisons were made according to the data obtained from the field. The data obtained showed that energy consumption in cold stores increased by up to 30%, depending on operating conditions. Therefore, it is very important that cold stores are inspected by the relevant institutions after they are established and during their operation. Copyright © 2023 Karacan, Yilmaz and Yilmaz. 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12294/3846 Dalgalı Yüzeyli Isı Değiştirici Kanallarında Hız ve Sıcaklık Alanlarının “Rans” Tabanlı Türbülans Modelleri ile Sayısal İncelenmesi ve Deneysel Doğrulaması Aslan, Erman; Taymaz, Imdat; İslamoğlu, Yaşar; Parmaksızoğlu, Cem; Özçelik, Güven Levhalı ısı değiştiricilerinde yaygın olarak kullanılan periyodik dalgalı yüzeyli kanal için taşınımla ısı geçişi ve sürtünme faktörü sayısal incelenmiştir. Sayısal çalışmada Sonlu Hacimler Yöntemi (Finite Volume Method – FVM) kullanılmıştır. Realize edilebilir k-ε (Realizable k-ε), k-ω, Kayma Gerilmesi Taşınımı (Shear Stress Transport – SST) ve geçiş SST (transition SST) olarak adlandırılan, dört farklı Reynolds Ortalamalı Navier-Stokes (Reynolds Averaged Navier-Stokes Simulations – RANS) tabanlı türbülans modelleri kullanılarak elde edilen sonuçlar karşılaştırılmıştır. Önceki deneysel çalışmalardan elde edilen sonuçlar da sayısal sonuçları doğrulamak için kullanılmıştır. Çalışmalar, dalga eğim açısının 30° olduğu dalgalı yüzeyli kanallarda hava akışı için yapılmıştır. Prandtl sayısı 0.70 sabit kalırken, Reynolds sayısı 2000 ile 11000 arasında değiştirilmiştir. Nusselt sayısı, Colburn faktörü, sürtünme faktörü ve ısı geçişi iyileştirme performansı Reynolds sayısına bağlı olarak verilmiştir. Dalgalı yüzeyli geometrinin ve kanal yüksekliğinin etkileri ele alınmıştır. Deneysel ve sayısal sonuçlar arasında en iyi uyum SST modeli ile sağlanırken, en çok hata ise realize edilebilir k-ε modelden elde edilmiştir. 2018-01-01T00:00:00Z