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Öğe Aluminyum esaslı metal matris kompozit malzemelerin mekanik özellikleri(2004) Uygur, İlyas; Saruhan, HamitBu makalede, günümüzde yaygın olarak kullanılmaya başlanan metal matrisli kompozit malzemelerin tanımlanması, sınıflandırılması, üretim teknikleri, mekanik özellikleri ve uygulama alanları irdelenmiştir. Özellikle parçacık takviyeli alüminyum esaslı kompozit malzemelerin kimyasal kompozisyonları, takviye elemanlarının boyutları ve yüzde dağılımlarının mekaniksel özelliklere etkisi tartışılmıştır. Ayrıca, mühendislik uygulamalarında kullanılacak kompozitlerin hangi kriterlere göre seçilebileceği üzerinde durulmuştur. Bu malzemelerin en yaygın şekilde kullanıldığı uygulamalar hakkında detaylı bilgiler verilmiştir.Öğe Batı Karadeniz bölgesindeki dalga enerjisi potansiyelinin araştırılması(2006) Uygur, İlyas; Demirci, Recep; Saruhan, Hamit; Özkan, Arif; Belenli, İbrahimÇevreye zarar vermeyen doğal, temiz ve sürekli yenilenebilir enerji türlerinin başlıcaları, rüzgar, güneş, biyolojik, su ve dalga enerjisidir. Dalga enerjisi, ilk yatırım ve bakım giderlerinden başka masrafı olmayan, girdi bedeli gerektirmeyen, doğaya her hangi bir kirletici bırakmayan, ucuz, temiz, çevreci ve büyük potansiyele sahip bir enerji kaynağıdır. Üç tarafı denizlerle çevrili Türkiye için de dalga enerjisi, enerji sıkıntısı çektiğimiz şu günlerde ve ileriki yıllarda bir çözüm olabilecek durumdadır. Bu bağlamda Batı Karadeniz (Akçakoca) bölgesinde beş yıllık gözlemsel çalışmalar yapılmış ve bölgenin dalga enerji potansiyeli hesaplanmıştır. Meteoroloji verilerinin incelenmesi neticesinde bölgedeki dalga enerjisi güç potansiyeli, mevcut teknolojik sistemler için yetersiz olarak gözükmektedir. Gelişen teknolojiyle birlikte üretilen yeni enerji dönüştürücülerinin de gelişeceği gözünde bulundurularak, yetersiz olarak tespit edilen dalga enerjisi potansiyeli daha verimli bir şekilde değerlendirilebilir. Bu çalışma bundan sonraki araştırmalar için bir temel teşkil edebilecektir.Öğe Design optimization of mechanical systems using genetic algorithms(2003) Saruhan, Hamit; Uygur, İlyasThis paper-prcsents an algorithm for the design of minimum weight of speed reducer, gear train, subject to a specificd set of constraints. The study is p rimarily aimed to expose the potential of genetic algorithms, to discuss their application capabilities, and to show the concept of these algorithms as optiınization techniques and their scope of application by implementing them to the speed reducer. Results obtained for the minimum weight of speed reducer are prescnted to provide insight into the capabilities of these techniques. Genetic algorithms are efficient search techniqucs which are inspircd from natural genetics selection process to cxplore a given search space.Öğe Düzce ilindeki betonarme binaların yeniden yapılanma sürecinde incelenmesi(2006) Uygur, İlyas17 Ağustos ve 12 Kasım 1999 depremleri, yüzyılın en büyük deprem felaketlerinden birisi olup, Düzce ilinde çok büyük hasarlara neden olmuştur. Depremden sonra yapılan çalışmalarda, yıkılan veya hasar gören binaların çok katlı yapılar olduğu belirlenmiştir. Binaların hasar durumları Bayındırlık Bakanlığı elemanları tarafından, belirlenerek ağır, orta ve hafif hasarlı yapılar şeklinde sınıflandırılmıştır. Bu sonuçlara göre orta ve ağır hasar olan yapılarda güçlendirme çalışmalarına başlanmıştır. Bu çalışmada, yıkılmış ve/veya hasar görmüş yapılardan, inşaat çelik numuneleri ve beton numuneleri alınmış ve malzemelerin mühendislik özellikleri incelenmiştir. Bununla birlikte yeniden yapılanma sürecine giren Düzce'deki yeni binalarda kullanılan beton ve çelik numunelerinde mühendislik özellikleri incelenmiştir. Korozyona uğramış çelik donatıların mühendislik özelliklerinde ne gibi değişiklikler olduğu deneylerle belirlenmiş olup, üç farklı durumda elde edilen sonuçlar karşılaştırılmıştır. Açık havada 1 yıl süre ile korozyona maruz bırakılan numunelerden elde edilen deney sonuçlarının da standartları sağlamadıkları gözlenmiştir. Ayrıca sabit olmayan çekme hızlarındaki mühendislik özelliklerinin belirlenmesi amacı ile de deneyler yapılmıştır. Yüksek tuzlardaki çekme deneylerinde malzeme hızla pekleşerek gevrekleşmekte ve aniden kırılmaktadır. Yerinde yapılan incelemelerde, genel olarak binalarda kullanılan çelik donatıların, bir çoğu hurda demirden soğuk ve sıcak olarak haddehanelerde şekillendirilmiş olduğu ve istenilen standartları sağlamadığı, buna karşılık yeni yapılan binalarda kullanılan donatıların ise standartları büyük ölçüde sağladığı yapılan deneyler sonucunda belirlenmiştir. Depremde yıkılmış veya hasar görmüş binalardan alınan beton numunelerin yaklaşık % 60'inin standart dışı olduğu, donatılarda ise bu oranın yaklaşık olarak %75 olduğu belirlenmiştir.Öğe The effect of allotropic transformation temperature in diffusion-welded low-carbon steel and copper(Natl Acad Sciences Ukraine, Inst Metal Physics, 2006) Kurt, Adem; Uygur, İlyas; Mutlu, EkremDiffusion welding (DW) is a solid-state joining process, capable of joining a wide range of metal and ceramic combinations to produce both small and large components. In this study, low-carbon steel (AISI 1010) was joined to commercially pure copper by diffusion welding technique. Metallographic and mechanical examinations were carried out to determine the welding quality. Diffusion interfaces were investigated by scanning electron microscopy (SEM) and x-ray energy-dispersive spectroscopy (EDS) analysis in order to observe the effect of allotropic-transformation temperature on the amount of diffusing elements. It was found that Fe diffusion from AISI 1010 steel to copper at the transformation temperature of 845 degrees C was lower than the measurement at 770 degrees C. This low-diffusion amount at 845 degrees C was attributed to the consumption of the internal energy for the phase transformation. From the findings of this study, it can be concluded that the perfect diffusion welding can be done in the temperature just below the allotropic transformation. The shear strength in DW joints was also evaluated.Öğe Effect of porosity content on the weldability of powder metal parts produced by friction stir welding(Trans Tech Publications Ltd, 2007) Kurt, Adem; Uygur, İlyas; Ateş, HakanFriction stir welding technique (FSW) has many advantages in terms of tool design, rotational speed and traveling speed, and can be adjusted in a precise manner. It enables heat input into the system to be controlled. In this study, Aluminum powders were compacted at 350,400 and 450 MPa pressure and sintered at 450 degrees C temperature for 30 minutes in Ar atmosphere. Sintered powder metal parts were joined to each other by FSW at the speed of 1800 rpm and traveling welding speed 200 mm/min under a constant friction force. The results show that the amount of porosity affects the welclability of powder metallurgy (P/M) parts. Furthermore, the porosity and microstructural evolution of the Aluminum also affected the hardness values of the tested materials.Öğe The effect of shielding gas compositions for MIG welding process in mechanical behavior of low carbon steel(2004) Uygur, İlyas; Gülenç, BehçetThe present study is focused on the mechanical properties of the deposited material which was extracted from welded region. This study explains the effect of the shielding gas composition on tensile behavior, R = - 1 fatigue response and various temperature impact test results of MIG welded low carbon steels. In tensile tests, the strength values are increased with increase of CO2 content, whereas the ductility is decreased. In the fatigue tests, the fatigue strength and the number of cycles to failure enhanced as the content of CO2 increased. However, the impact toughness of the filler material is seriously influenced by the content of the shielding gas. An increase in CO2 content caused significant decrease in toughness values at all temperatures.Öğe The effect of TIG welding on microstructure and mechanical properties of a butt-joined-unalloyed titanium(Croatian Metallurgical Soc, 2005) Uygur, İlyas; Dogan, IMicrostructures, properties and technical parameters of welding specimen of 3 mm thick sheets of commercially pure titanium have been studied. The results indicate that the TIG welding process is suitable for commercially pure titanium, full penetration and the welding seam without defects can be obtained. The tensile, bending and hardness properties of the joints are corresponding to matrix structure. The mechanical properties of the three welded joints are similar to each other and comparable to those of the base material.Öğe Effects of temperature on the weldability of powder metal parts joined by diffusion welding(Trans Tech Publications Ltd, 2007) Kurt, Adem; Uygur, İlyas; Ateş, HakanDiffusion welding is an advanced bonding process in which similar or dissimilar materials can be bonded in solid state. In this study, aluminium composite (5% and 15% WC) powders were compacted at 450 MPa pressure and sintered at 550 degrees C for 45 minutes in argon atmosphere.and joined each other by diffusion bonding. The bonding temperatures (585 degrees C, 600 degrees C, 615 degrees C) and dwell time (185 min) were chosen for the welding process at constant 20 MPa. It has been observed that these variations on the welding parameter strongly affected the microstructure and the weldability of the materials.Öğe Elution characteristics and mechanical properties of calcium sulfate-loaded bone cement containing teicoplanin(Springer Tokyo, 2007) Tüzüner, Tolga; Uygur, İlyas; Şencan, İrfan; Haklar, Uğur; Oktaş, Birhan; Özdemir, DavutBackground. Acrylic bone cement is the most widely used drug delivery system clinically. It has already been shown that antibiotic release is significantly increased when calcium sulfate-loaded acrylic bone cement is used. However, there is no information yet about the mechanical responses of these composite materials. Thus, the purpose of this study was to investigate the effect of calcium sulfate on the elution characteristics and mechanical behavior of teicoplanin-loaded acrylic bone cement. Methods. Four groups of acrylic bone cements (GI, GII, GIII, GIV) were prepared using the same liquid/powder ratios. After mixing, the bone cement and additive mixtures were packed into different-type molds to prepare the specimens for the elution and mechanical tests. All of the specimens were tested for two conditions (dry and human plasma solution). The mechanical tests included the setting time (hardness) and tensile, bending, and compression strengths. The fracture surfaces of the failed samples were also examined by scanning electron microscopy. Results. Teicoplanin release in the calcium sulfate powder added groups (GIII and GIV) was higher than that of GII. When the calcium sulfate and teicoplanin were added on acrylic bone cement, the compressive, bending and tensile strength, hardness values, and elastic modulus decreased. Also, further reductions were evident in human plasma solution. Conclusions. Although mechanical properties of tested specimens decreased, all of the results obtained were higher than those required by the American Society for Testing and Materials Standards, but further investigations are necessary before making definitive statements for clinical applications.Öğe The fatigue behaviour of SiC particulate reinforced 2124 aluminium matrix composites(Natl Acad Sciences Ukraine, Inst Metal Physics, 2004) Uygur, İlyas; Evans, W. J.; Bache, Martin; Gülenç, BehçetIn this investigation paper, the cyclic stress-controlled fatigue response and fracture behaviour of aluminium alloy 2124 discontinuously reinforced with Silicon-Carbide Particulates (SiCp) are presented. The influence of volume fraction (17% and 25% vol.), particle size (2.5 mum and 15 pm), and stress ratio (R = 0.1 and R = 0.5) are examined. In addition, the cyclic fatigue tests were carried out at elevated temperatures (200 degreesC and 250 degreesC). Volume fraction had a significant influence on fatigue lives. An increase in stress ratio and temperature significantly diminished the fatigue life responses of the base alloy and the composites. At elevated temperatures, the tensile properties of the materials decreased, thus, the fatigue lives and their strength diminished. Fracture surfaces revealed that the materials failed in ductile manner, with the evidence of the shallow dimples.Öğe Kaynaklı konstrüksiyonlarda tasarım(2000) Uygur, İlyas; Mendi, Faruk; Külekci, M. KemalBu çalışmada kaynaklı yapıların tasarımında göz önünde bulundurulması gereken sınırlılıklar üzerinde durulmuştur. Farklı kesit kalınlığına sahip parçaların kaynağı ve optimum ısı girişinin sağlanması ile dairesel kesitli boruların kaynağında, distorsiyonları en aza indirgeyen yöntem ve teknikler irdelenmiştir. Tüm kaynak yöntemlerinde karşılaşılan ortak sorunlardan birisi, tasarıma ait muhtemel çözümler arasından uygun olanının seçilmesidir. Bu bağlamda endüstriyel uygulamalarda sıklıkla kullanılan üst üste bindirme ve $\bot$ formundaki kaynaklı birleştirmelerde, meydana gelebilecek distorsiyonları belirlemede kullanılan belli başlı formüller ile deneysel çalışma sonuçları karşılaştırılmıştır.Öğe Low cycle fatigue properties of 2124/SiCp Al-alloy composites(2002) Uygur, İlyas; Külekci, Mustafa Kemalloading conditions. The influence of volume fraction (17 and 25 vol%), particulate size (2.5 and 15 µm) of reinforcement particles and strain ratio (R=0, R=0.5 and R= -1) are examined for 2124 Al-alloy-T4 composites. Increasing the content of SiCp results in the degradation of strain control fatigue properties. The monotonic and cyclic stress-strain response of the 2124Al – (25 vol% 2.5 µm) SiCp composite was significantly altered by strain ratio values. Fatigue cracks frequently initiated from intensively stress concentrated regions. Increasing volume fraction and particle sizes result in early crack initiationÖğe Microstructure and performance in diffusion welded joints of Al +5-10-15% WCp composites(Trans Tech Publications Ltd, 2007) Uygur, İlyasJoining parts by diffusion welding is one of the recent manufacturing techniques, since it allows manufacturing of similar or dissimilar parts, and complex components with high precision. It is difficult to weld Aluminium and its composites by conventional fusion welding techniques. Thus, In this study, diffusion welding technique was applied to weld Al+5-10-15% WCp composites in argon gas. An experimental set up has been designed and series of experiments have been performed, Metallographical examinations have been carried out to determine the welding quality. It was concluded that changes in volume fraction of the reinforcement particles strongly affect the weldability of the materials and their microstructures.Öğe Microstructure and performance in diffusion welded joints of Al+5-10-15% WCp composites(Trans Tech Publications Ltd, 2007) Uygur, İlyasJoining parts by diffusion welding is one of the recent manufacturing techniques, since it allows manufacturing of similar or dissimilar parts, and complex components with high precision. It is difficult to weld Aluminium, and its composites by conventional fusion welding techniques. Thus, In this study, diffusion welding technique was applied to weld Al+5-10-15% WCp composites in argon gas. An experimental set up has been designed and series of experiments have been performed, Metallographical examinations have been carried out to determine the welding quality. It was concluded that changes in volume fraction of the reinforcement particles strongly affect the weldability of the materials and their microstructures.Öğe Microstructure and wear properties of AISI 1038 H steel weldments(Emerald Group Publishing Limited, 2006) Uygur, İlyasPurpose - To provide information about technical data; wear behaviour of worn rotor parts in mining industry and for the other application of ferrous alloys. Design/methodology/approach - Wear behaviour of the various filler wires were tested (tensile, hardness, and wear) and compared with each other in the light of microstructure, chemical, and mechanical properties. Findings - The results showed that the wear rates were significantly increased with the increasing load, welding current, wear distance and poor mechanical properties. A larger amount of C, Cr, and Mn specimen showed the best wear resistance since it contained a number of hard MC-type carbides and coarse grains. Furthermore, for all materials the weight loss increases linearly with the increasing of welding arc current, load and wear distance. Research limitations/implications - It would be interesting to search about the toughness values and fatigue behaviour of these materials. It could be the good idea for future work could be concentrated fracture surface analysis of these materials. Practical implications - For these materials choosing the right chemical composition of the filler material, certain arc current and ideal microstructure is crutial for the wear response. Originality/value - The main value of this paper is to contribute and fulfil the mechanical properties of welding wires that is being studied so far in the literature such as the effects of chemical composition, applied road range, and arc current on the tensile, hardness and wear behaviours of the welding wires.Öğe Optimization of MQL parameters using the Taguchi method in milling of nickel based Waspaloy(Gazi Univ, 2017) Yıldırım, Çağrı Vakkas; Kıvak, Turgay; Erzincanlı, Fehmi; Uygur, İlyas; Sarıkaya, MuratThis study aimed to investigate the effect of the minimum quantity lubrication (MQL) parameters such as cutting oil type, flow rate, milling method, pulverization distance and nozzle type on average surface roughness (Ra) in milling of nickel based Waspaloy super alloy. During milling experiments, constant cutting speed (45 m/min), feed rate (0.1 mm/rev) and depth of cut (0.5 mm) were selected as machining parameters. Four different types of oil (vegetable, synthetic, mineral and mineral-synthetic), four different flow rates (25, 50, 75 and 100 ml/h), two different milling methods (down milling and up milling) two pulverization distances (25 and 50 mm) and two different nozzle types were chosen as MQL parameters. The results were analyzed using 3D surface graphs, signal-to-noise ratio (S/N) and main effect graphs of means. Optimal MQL parameters were determined using the S/N ratio. Mathematical models have been created for surface roughness. The analysis results indicated that the dominant factors were oil type and flow ratio on surface roughness. In addition, confirmation test results showed that the Taguchi method was very successful in the optimization of MQL parameters in order to obtain minimum surface roughness in milling of Waspaloy super alloy.Öğe Tensile behavior of powder metallurgy processed (Al-Cu-Mg-Mn /SiCp composites(2004) Uygur, İlyasThe tensile behavior of Al-Cu-Mg-Mn alloy matrix composites produced by a powder metallurgy process was investigated as a function of particle size and volume fraction in a naturally aged condition (T4). Microstructural examinations have enabled identification of particles and grain structure of the materials. The results indicated that tensile properties of the composites significantly improved in the yield strength, UTS and elastic modulus, on incorporation of hard, brittle ceramic particles as compared to unreinforced counterparts. On the other hand, ductility decreased considerably due to the brittle ceramic particles. The results were discussed in the light of microstructures. © Shiraz University.
