Makale Koleksiyonu | Makine Mühendisliği Bölümü / Department of Mechanical Engineering
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Öğe Investigation of residual stresses induced by milling of compacted graphite iron by x-ray diffraction technique(Springer, 2024-04) Kara, Mehmet Emre; Kuzu, Ali Taner; Bakkal, MustafaThis study investigates the relationship between residual stresses, cutting parameters, and machining performance in the milling process of compacted graphite iron (CGI). X-ray diffraction (XRD) analysis is employed to measure residual stresses on the cast and milled surfaces, while cutting force modeling is utilized to calculate the tangential force, power, and active work. The results demonstrate that tensile residual stresses are predominant on the milled surfaces, attributed to the both mechanical and thermal loads generated during milling. By analyzing various cutting conditions, it is observed that lower feeds contribute to reduced plastic deformation, resulting in lower residual stress levels. Additionally, higher cutting speeds lead to higher temperatures, but due to the shorter machining time, heat accumulation is limited, resulting in higher residual stresses, especially at low feeds. At high feeds, residual stresses decreased as the cutting speed increased. The interplay between cutting parameters and residual stresses highlights the need for optimizing cutting conditions to enhance fatigue strength in CGI components. These findings provide valuable insights for process optimization and quality control in the milling of CGI materials.Öğe Neural network steering control algorithm for autonomous ground vehicles having signal time delay(SAGE Publications Ltd, 2024-03) Dinçmen, ErkinAn adaptive neural network–based steering control algorithm is proposed for yaw rate tracking of autonomous ground vehicles with in-vehicle signal time delay. The control system consists of two neural networks: the observer neural network and the controller neural network. The observer neural network adapts itself to the system dynamics during the training phase. Once trained, the observer neural network cooperates with the controller neural network, which constantly adapts itself during the control task. In this way, an adaptive and intelligent control structure is proposed. Through simulation studies, it has been shown that while a proportional-integral-derivative type steering controller fails to perform its control task in case of steering signal delay, the proposed control algorithm manages to adapt itself according to the control problem and achieves reference yaw rate tracking. The robustness of the control algorithm according to the signal delay magnitude has been demonstrated by simulation studies. A rigorous Lyapunov stability analysis of the control algorithm is also presented.Öğe Tribo-corrosion behavior of electroplating, nitrocarburizing, and QPQ processes on barrel finishing(Walter de Gruyter GmbH, 2023-11-27) Yücel, Aysu Hande; Yılmaz, Alpay; Bakkal, Mustafa; Kuzu, Ali TanerIn this study, the effects of nitrocarburizing, QPQ, and Cr coating on the surface properties of 32CrMoV12-10 gun barrels are discussed. Hardness measurements, pin-on-disc tests, and anodic polarization tests were performed to examine the hardness values, wear resistance, friction coefficient, and corrosion resistance. The hardness of the specimen treated with QPQ was found to be the highest. Comparing the hardness profiles, it was observed that the casing depth of the nitrocarburized sample was shallower than that of the QPQ-treated sample. The pin-on-disc test revealed that the nitrocarburized sample exhibited a high coefficient of friction, while the Cr-coated sample showed the lowest coefficient of friction. Analyzing the Tafel polarization curve, it was determined that the nitrocarburized and QPQ-treated specimens demonstrated similar levels of corrosion resistance. However, it can be noted that the QPQ-treated specimen had a slightly lower corrosion rate.Öğe The development of a hybrid cutting model for workpiece temperature distribution via advection heat partition approach(Springer Science and Business Media Deutschland GmbH, 2023-04-15) Kara, Mehmet Emre; Kuzu, Ali Taner; Bakkal, MustafaThis paper presents a novel hybrid cutting model for the prediction of workpiece temperature distribution during the dry milling process of compacted graphite iron (CGI). The hybrid model consists of an analytical force model based on a mechanistic approach and finite element analysis (FEA) based on the thermal model. The heat generated during the milling process transferred to the workpiece is computed via the advection heat partition model. The workpiece temperature distribution obtained through the heat loads, using as boundary conditions in the FEA, was calculated by means of cutting forces. The developed force and thermal models have been experimentally validated, and good agreement between the measured and calculated results has been observed. The energy and active work calculations show that by doubling the feed during CGI milling, an energy saving of about 10% is achieved despite almost doubling the cutting forces.Öğe Analysis of mechanical behavior of termoplastic composites(Necip Fazıl YILMAZ, 2022-03-04) Kuzu, Ali Taner; Kosemen, Elifnur; Yücel, Aysu Hande; Bakkal, MustafaThis paper presents the effect of fiber orientation on the tensile, compression, impact, and flexuralproperties of glass fiber reinforced acrylic-based thermoplastic composites. The mechanical behaviorof three different composite plates, produced by the resin transfer molding (RTM) method, with0°/90°/45°, 0°/90° and ±45° glass fiber orientations were investigated by carrying out tensile,compression, three-point bending and Charpy impact tests. A Weibull distribution model wasimplemented to explain the variation in mechanical properties of the acrylic-based composite.According to Weibull analysis results with 63.2% probability, the highest tensile strength (561 MPa),compressive strength (293 MPa) and impact values (19.44 J) were obtained when the plate with0°/90° glass fiber orientation was tested, whereas the highest flexural strength was obtained when theplate with 0°/90°/45° was tested.Öğe Eksenel çıkışlı radyal fan sistemi tasarımı(TMMOB Makina Mühendisleri Odası, 2021-11) Develi, Salih Deniz; Sönmez, Olgun; Ayder, ErkanRadyal fanlar hava veya gaz nakline gerek duyulan klima santralleri, havalandırma tesisatları vb. gibi pek çok yapıda kullanılmaktadır. Son zamanlarda radyal fanların performans artırımlarına yönelik pek çok çalışma yapılmakta ve fan kanatları üzerinde yapılan değişiklikler ile yüksek performanslı fanlar elde edilebileceği vurgulanmaktadır. Bilindiği üzere radyal fanlarda, akış fanın içerisine eksenel olarak girip 90° dönerek ve radyal olarak çıkmaktadır. Klima santrallerinde çoğunlukla çift emişli salyangozlu radyal vantilatörler ve salyangozsuz plug fanlar kullanılmaktadır. Plug fanlar, salyangozlu vantilatörlere göre daha düşük verimli olsa da sağladığı montaj kolaylığı ve yer tasarrufu üstünlüğü nedeniyle daha yaygın olarak kullanılmaktadırlar. Plug fanlarda, rotorda basınçlandırılmış hava, çıkışta enerjisinin önemli bir kısmını yitirmekte ve hava hızındaki büyük değişim sistemin gürültü seviyesinin artması ile sonuçlanmaktadır. Birden fazla fanın dizilmesi ile oluşturulan fan demeti uygulamalarında, fanların birbirleriyle etkileşimini ortadan kaldırma amacıyla fanların aralarına belirli uzaklıklarda ayırıcı duvarlar yerleştirilmekte ve bu nedenle sistem boyutları büyümektedir. Rotor çıkışına bir eksenel yönlendirici yerleştirilmesiyle plug fanların bu dezavantajlarının ortadan kaldırılabileceği öngörülmektedir. Plug fan çıkışındaki akışın eksenel hale getirilmesi, klima santrallerindeki diğer ekipmanların (filtre, eşanjör, nemlendirme ünitesi vb.) performanslarını da arttıracaktır. Bu nedenle bu çalışma kapsamında radyal fanın hemen çıkışına konumlandırılan, akışı 90° döndürerek eksenel hale getiren bir yönlendirici bileşen tasarlanmış ve performansı hesaplamalı akışkanlar dinamiği (HAD) analizleri ile incelenmiştir. Ayrıca tasarlanan bu yönlendiricinin fan performansı üzerindeki etkisi de çalışılmıştır. Varılan sonuç yönlendiricinin sistemin debisini ve verimini arttırdığı yönündedir.
