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Öğe Otomotiv fren balatalarının sürtünme performansında sic etkisi(Uludağ Üniversitesi, 2012-06) Altun, Şehmus; Öner, Cengiz; Sugözü, İlkerBu çalışmada, yüksek mukavemet, düşük aşınma, daha fazla yük ve sıcaklık dayanımı özelliklerine sahip SiC içeren balata numunelerinin sürtünme katsayısı ve aşınma dayanımına etkisi incelenmiştir. Balata bileşeni içerisine %5, %10 ve %15 SiC ilave edilmiştir. Sonuç olarak, SiC oranı arttıkça aşınma direnci artmış ve sürtünme katsayısı azalmıştırÖğe Investigation of plasma arc cutting parameters with type-2 fuzzy set and system(De Gruyter, 2013-10) Çelik, Yahya Hışman; Özek, Cebeli; Bulut Özek, MüzeyyenThe objective of the present study was it to design a type-2 fuzzy set and system in order to predict surface roughness and hardness depending on the parameters (material thickness, cutting speed, arc voltage and current) of the plasma arc cutting process of S235JR sheet materials. Therefore, some experimental studies were conducted. The experimentally determined data were used to describe the type-2 fuzzy set and system. Type-2 fuzzy set and system was found to be usefull to predict surface roughnes and hardness. According to the obtained values, the best surface roughness and the values closest to the hardness of the raw material were obtained at 1500 mm/min cutting speed, 8 mm material thickness, 115 V arc voltage and 80 A current.Öğe Biodiesel production from inedible animal tallow and an experimental investigation of its use as alternative fuel in a direct injection diesel engine(Elsevier, 2009-02-15) Altun, Şehmus; Öner, CengizIn this study, a substitute fuel for diesel engines was produced from inedible animal tallow and its usability was investigated as pure biodiesel and its blends with petroleum diesel fuel in a diesel engine. Tallow methyl ester as biodiesel fuel was prepared by base-catalyzed transesterification of the fat with methanol in the presence of NaOH as catalyst. Fuel properties of methyl ester, diesel fuel and blends of them (5%, 20% and 50% by volume) were determined. Viscosity and density of fatty acid methyl ester have been found to meet ASTM D6751 and EN 14214 specifications. Viscosity and density of tallow methyl esters are found to be very close to that of diesel. The calorific value of biodiesel is found to be slightly lower than that of diesel. An experimental study was carried out in order to investigate of its usability as alternative fuel of tallow methyl ester in a direct injection diesel engine. It was observed that the addition of biodiesel to the diesel fuel decreases the effective efficiency of engine and increases the specific fuel consumption. This is due to the lower heating value of biodiesel compared to diesel fuel. However, the effective engine power was comparable by biodiesel compared with diesel fuel. Emissions of carbon monoxide (CO), oxides of nitrogen (NOx), sulphur dioxide (SO2) and smoke opacity were reduced around 15%, 38.5%, 72.7% and 56.8%, respectively, in case of tallow methyl esters (B100) compared to diesel fuel. Besides, the lowest CO, NOx emissions and the highest exhaust temperature were obtained for B20 among all other fuels. The reductions in exhaust emissions made tallow methyl esters and its blends, especially B20 a suitable alternative fuel for diesel and thus could help in controlling air pollution. Based on this study, animal tallow methyl esters and its blends with petroleum diesel fuel can be used a substitute for diesel in direct injection diesel engines without any engine modification.Öğe Effects of cutting parameters and point angle on thrust force and delamination in drilling of CFRP(De Gruyter, 2014-11-14) Çelik, Yahya Hışman; Kılıçkap, Erol; Yardımeden, AhmetParts made of composite materials are generally produced by near-net-shape technology. However, additional machining operations such as drilling are often required to facilitate components assembling. Drilling of composite materials is also a common process in the assembly of aerospace and automotive composite structures. During drilling, unlike the conventional materials, a few damage forms may take place. Among these damage forms, the delamination is the most important one. Therefore, the experimental studies carried out on drilling of CFRP composite materials for determining optimum processing parameters are of great importance. In this particular study, delamination in CFRP composites caused by drilling was investigated. The composite material was drilled under various spindle speeds, feed rates and drill point angles. The results showed that delamination and thrust forces were affected by cutting parameters. It was demonstrated that feed rate and drill point angle make the largest contribution to the overall performance.Öğe Doğal fiber takviyeli kompozitler üzerine bir derleme çalışması(IESS Publishing, 2019-06) Çelik, Yahya Hışman; Yalçın, RojinÖğe The comparison of engine performance and exhaust emission characteristics of sesame oil-diesel fuel mixture with diesel fuel in a direct injection diesel engine(Elsevier, 2008-01-09) Altun, Şehmus; Bulut, Hüsamettin; Öner, CengizThe use of vegetable oils as a fuel in diesel engines causes some problems due to their high viscosity compared with conventional diesel fuel. Various techniques and methods are used to solve the problems resulting from high viscosity. One of these techniques is fuel blending. In this study, a blend of 50% sesame oil and 50% diesel fuel was used as an alternative fuel in a direct injection diesel engine. Engine performance and exhaust emissions were investigated and compared with the ordinary diesel fuel in a diesel engine. The experimental results show that the engine power and torque of the mixture of sesame oil-diesel fuel are close to the values obtained from diesel fuel and the amounts of exhaust emissions are lower than those of diesel fuel. Hence, it is seen that blend of sesame oil and diesel fuel can be used as an alternative fuel successfully in a diesel engine without any modification and also it is an environmental friendly fuel in terms of emission parameters.Öğe Effect of tightening torque on the fatigue strength of bolted composite lap joints(Kilis 7 Aralık Üniversitesi, 2016) Topkaya, Tolga; Solmaz, Murat YavuzÖğe Şanlıurfa ilinde yatay yüzeye gelen anlık global güneş ışınımının modellenmesi(Dicle Üniversitesi, 2019-03-15) Karakaya, Hakan; Kallioğlu, Mehmet Ali; Avcı, Ali Serkan; Ercan, UmutBu çalışma ile Şanlıurfa ilinin iklim özellikleri ve topografik yapısı göz önüne alınarak yatay düzleme gelen aylık ortalama günlük global güneş radyasyonunun tespit edilebilmesi için literatürde yer alan 5 farklı model incelenmiştir. Sonuçlar istatistiksel karşılaştırma metotları, belirlilik katsayısı (R²), ortalama yüzde hata (MPE), sapma hatası (MBE), ortalama mutlak hata yüzdesi (MAPE), bağıl hata karesi (SSRE), bağıl standart hata (RSE), ortalama karekök hatası (RMSE), bağıl hata yüzdesi (e) ve t-istatistik (t-sat) ile olmak üzere dokuz farklı istatistik yöntemi ile karşılaştırılmıştır. Şanlıurfa ili için en uygun yaklaşım için bir sonuç verilmiştir. İstatistiksel hata sonuçlarına göre Cheegar ve Chibani Modeli yatay düzleme gelen global güneş ışınımı için Şanlıurfa ilinde kullanılacak en uygun model olarak belirlenmiştir. Sonuç olarak Şanlıurfa ili toplam güneş radyasyonu tahmini için polinom modelin tercih edilmesi önerilmiştir. Bu model verilerine göre Şanlıurfa ili için yıllık güneş enerjisi potansiyeli 4332,020 W/m2 /ay olarak belirlenmiştirÖğe Combustion, performance and emissions of a diesel power generator fueled with biodiesel-kerosene and biodiesel-kerosene-diesel blends(Elsevier, 2017-02-05) Bayındır, Hasan; Işık, Mehmet Zerrakki; Argunhan, Zeki; Yücel, Halit Lütfi; Aydın, HüseyinHigh percentages of biodiesel blends or neat biodiesel cannot be used in diesel engines due to high density and viscosity, and poor atomization properties that lead to some engine operational problems. Biodiesel was produced from canola oil by transesterification process. Test fuels were prepared by blending 80% of the biodiesel with 20% of kerosene (B80&K20) and 80% of the biodiesel with 10% of kerosene and 10% diesel fuel (B80&K10&D10). Fuels were used in a 4 cylinders diesel engine that was loaded with a generator. Combustion, performance and emission characteristics of the blend fuels and D2 in the diesel engine for certain loads of 3.6, 7.2 and 10.8 kW output power and 1500 rpm constant engine speed were experimented and deeply analyzed. It was found that kerosene contained blends had quite similar combustion characteristics with those of D2. Mass fuel consumption and Bscf were slightly increased for blend fuels. HC emissions slightly increased while NOx emissions considerably reduced for blends. It was resulted that high percentages of biodiesel can be a potential substitute for diesel fuel provided that it is used as blending fuel with certain amounts of kerosene.Öğe Köşeleri yuvarlatılmış eşkenar üçgen delikli kompozit levhaların gerilme ve yüzde uzama davranışlarının deneysel olarak incelenmesi(Nevşehir Hacı Bektaş Veli Üniversitesi, 2016-04) Adin, Hamit; Ergün, Raşit Koray
