Yazar "Bakkal, Mustafa" seçeneğine göre listele
Listeleniyor 1 - 9 / 9
Sayfa Başına Sonuç
Sıralama seçenekleri
Yayın 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.Yayın 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.Yayın Effect of scanning strategies and laser parameters on metal-composite joining(Bellwether Publishing, 2021-07-27) Kuzu, Ali Taner; Karagüzel, Umut; Erbay, Batıray; Bakkal, MustafaThis study presents an investigation on the effectiveness, automation characteristics, and mechanics of joints between different material types namely glass ?ber reinforced plastics (GFRPs) and SS304 stainless steel using an industrial Nd: YAG continuous-wave laser welder and a 2-axis custom design jig. The custom design jig includes computer-controlled (CNC) step motors, which provide high accuracy position control of the selected laser patterns. Four different patterns (Linear Curve, Hilbert Curve, Triangle Weave, and Curlique Weave) are investigated under different process parameters (laser power, lap joint length, and traveling speed) to obtain more robust joints. The strength of the joint is examined by variance analysis and found that the laser power and the pattern are the most important factors. Tensile shear tests present that the best-resulted joint carried around 4000 N before fracture. Polymer vaporization resulted in sub-millimeter sized bubbles that are widely formed inside the molten zone of the GFRP specimen. Therefore, a strong joint between GFRP and SS304 stainless steel could be obtained by a direct laser joining process at low power, with load adaptable space-filling curve patterns and without needing surface pretreatment, sophisticated clamps or high clamping forces.Yayın Experimental analysis on drilling of Al/Ti/CFRP hybrid composites(Bellwether Publishing, 2021-01-25) Kayihan, Mete; Karagüzel, Umut; Bakkal, MustafaCarbon fiber reinforced composites (CFRP) have superior mechanical properties such as high strength/density ratio, and good damping ability. CFRP which is frequently used in parts in the aviation industry can also be single or stacked together with titanium and aluminum alloys. However, delamination could occur on the CFRP surfaces after drilling which leads to deterioration in mechanical properties. Therefore, in this paper, the effect of process parameters and stack order on cutting force, torque are investigated. The tests were carried out at three different drilling speeds and feed rates on a CNC vertical machine tool by using a solid carbide cutting tool. The results of hole quality indicate that the process outputs are significantly affected by process parameters and stack order. The force and torque values obtained at high drilling speeds and low feed rates are independent of the stack order. However, the stacking order is determined to be the most effective parameter for the thrust force and torque values. The force generated during the Ti/CFRP/Al stack in which the highest force value is approximately 50% higher than the lowest force which occurs on Al/Ti/CFRP stack. The surface roughness value measured during the Al/Ti/CFRP stack is approximately half of the other stack order.Yayın Frezeyle tornalamada takımda ortaya çıkan termal deformasyonların modellenmesi(Gazi Universitesi Muhendislik-Mimarlik, 2017) Karagüzel, Umut; Bakkal, Mustafa; Budak, ErhanFrezeyle tornalama işleminde işlemiş parça doğruluğu ve üretkenliği arttırarak işlem performansını iyileştirmek kesme kuvvetlerini ve takım ucundaki ısı kaynaklı deformasyonları kontrol etmekle mümkündür. Bu çalışmanın amacı frezeyle tornalama sırasında ortaya çıkan ısı kaynaklı deformasyonları belirlemek ve bunları basınçlandırılmış soğuk hava kullanarak azaltmaktır. Kesme kuvvetleri, takım sıcaklıkları ve deformasyonlar sonlu elemanlarla modellenmiş ve deneylerle doğrulanmıştır. Kuru kesme koşullarında bu deformasyonların paso derinliğinin %40’ı kadar olabileceği ve bunun sonlu elemanlarla tahmin edilecebileceği gösterilmiştir. Ayrıca bu deformasyonlar soğuk hava ile %65’e kadar azaltılabilir. Termal deformasyonlara ek olarak çalışmada takım aşınması ve işlenen parçada yüzey pürüzlülüğü değerleri de ölçülmüştür ve özellikle frezeyle tornalamada yüzey pürüzlülüğü değerlerinin taşlamadaki kadar iyi olabileceği gösterilmiştir.Yayın 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.Yayın Mechanical and thermal modeling of orthogonal turn-milling operation(Elsevier Science BV, 2017) Karagüzel, Umut; Bakkal, Mustafa; Budak, ErhanTurn-milling is a relatively new machining technology which is performed for cutting of symmetrical or non-symmetrical rotational parts. To improve productivity, determination of cutting parameters in turn-milling is crucial. However, experimental approach is costly, hence it is important to develop predictive models, especially analytical models, for improved process outputs such as cutting force, MRR, cutting temperature etc. In this study, cutting forces, part quality, MRR, cutting temperatures are modeled for orthogonal turn-milling operation. The developed models are verified by experiments. The results show that the eccentricity parameter in turn-milling has a significant effect on process outputs.Yayın Sıcak dövme kalıplarına infrared (kızılötesi) yöntemi ile ön ısıtma uygulanmasına yönelik deneysel ve teorik analiz(Makina Tasarım ve İmalat Derneği, 2020-09-19) Karagüzel, Umut; Kuzu, Ali Taner; Korap, Vedat; Çilingir, Hasan; Bakkal, MustafaSıcak dövme işlemi, üretim teknolojisinin önemli bir parçasınıoluşturur. Sıcak dövmede uygulanan ısı enerjisi ile parçanın akmadayanımı azalır böylelikle şekil verme kabiliyeti artarak daha karmaşıkgeometrili parçaların üretilmesine imkân tanır. Ancak artan sıcaklıklabirlikte kalıp dayanımında da düşüş yaşanması kalıp ömrünün azalmasınave üretim maliyetlerinin artmasına neden olur. Kalıp ömrünü azaltanetkenlerden biri de kalıbın dövme işlemi süresince karşılaştığı yükseksıcaklık farklarıdır, bunun önüne geçebilmek için dövme işlemi öncesindekalıba ön ısıtma işlemi uygulanır. Bu çalışmada sıcak dövme sırasındadengeli ve homojen bir ön ısıtma için infrared ısıtıcı geliştirilmiş veüretime uygulanmıştır. İnfrared ısıtıcının verimi ısıtılıcak kalıbın yüzeydurumuna da bağlı olduğundan, çalışmada kalıp yüzeyi için çeşitlikaplamalar ve yüzey uygulamaları denenmiş ve bunların verimlerikarşılaştırılmıştır. Çalışmada ısıtma prosesinin sonlu elemanlar modelide geliştirilmiş ve sıcaklık sonuçları deneysel sonuçlarlakarşılaştırılmıştır. Geliştirilen model ile sıcaklıkların en fazla % 9’luk birfark ile tahmin edilebileceği ortaya konulmuştur. Bu modelle ayrıca farklıkalıp geometri ve kalıp derinliğinde, istenilen sıcaklığa ulaşabilmek içingereken ısıtma süresi kolaylıkla belirlenebilir. Çalışma sonucundainfrared ısıtıcı ile kalıbın ön ısıtıma işleminin homojen ve verimli birşekilde yapılabiliceği gösterilmiştir.Yayın 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.
