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3 ve 5 kromlu çeliklerde tantalyum ve krom ilavesinin mikroyapıya ve çentik darbe direncine etkisi
(Selçuk Üniversitesi, 2019) Arıcı, Gökhan; Acarer, Mustafa; Uyaner, Mesut
Krom molibden (tungsten) [Cr-Mo (W)] çelikleri yüksek sıcaklık ve basınçlı buharın geçtiği petrokimya endüstrisindeki, enerji santrallerindeki vb. kullanılan borularda tercih edilmektedir. Bu şartlarda gerekli mukavemetin sağlanması çelikteki alaşım elementlerine bağlıdır. Alaşım elementlerinin kompozisyonlarının değişmesi çeliğin mikroyapısal ve mekanik özelliklerini değiştirmektedir. Bu çalışmada, daha önce üretimi yapılan Cr-Mo (Cr-W) çeliklerine alternatif olabilecek, ağırlıkça % 3, % 5 Cr ve % 3 W ana alaşım elementlerini içeren düşük Cr’lu çelikler döküm yolu ile üretilip sıcak olarak haddelenmiştir. Bu çalışmada farklı oranlarda Cr ve Ta içeren çeliklerin mikroyapıları ve çentik darbe dirençleri incelenmiştir. 3 Cr’lu alaşımlarda mikroyapıda ferrit ve beynit gözlemlenirken, 5 Cr’lu alaşımlarda mikroyapıda beynit ve martenzit gözlemlenmiştir. Ayrıca, Cr ve Ta ilaveleri alaşımların sünekliklerinde azalmaya sebep olmuştur.
An axisymmetric contact problem for a bi-layered transversely isotropic slab resting on a rigid circular support
(Selçuk Üniversitesi Mühendislik-Mimarlık Fakültesi, 2012) Bay, M. İlker; Dağhan, Behcet; Uyaner, Mesut
This paper is concerned with the continuous contact problem of two transversely isotropic layers resting on a circular support. The external load is applied to the layers by a rigid cylindrical block. It is assumed that the contact between all surfaces is frictionless and body forces are not taken into account. The problem is formulated in terms of singular integral equations obtained from the continuous contact position. Equations are solved numerically by using the Gauss-Chebyshev integration method. Furthermore, numerical results as pressure distributions under the rigid cylindrical block are given for different material combinations.
Contact Problem for a Transversely Isotropic Cylinder Radially Compressed by a Rigid Toroidal Indenter
(Walter De Gruyter Gmbh, 2006) Avcı, Ahmet; Yapıcı, Ahmet; Uyaner, Mesut
In this study, an elastostatic contact problem for a radially compressed transversely isotropic cylinder subjected to radial compression through a circumferential indenter is considered. The extent of the contact region and the stress distribution are sought. The problem is formulated for an elastic cylinder in the absence of body forces. It is assumed that the contact between the cylinder and the rigid indenter is frictionless and only compressive normal tractions can be transmitted through the interface. Due to the geometry of the configuration, Fourier transform techniques are chosen. The problem is reduced to a singular integral equation. It is reduced to linear algebraic equations system by using Gauss Chebyshev Integration Formulae. This system is solved by using the Gauss Elimination method. The values are evaluated for various discrete points. Numerical results for the radial stress and the distance characterizing the contact area are given in graphical form for single circular smooth indenter.
Correlation Between Machinability and Chip Morphology of Austempered Ductile Iron
(AMER SOC TESTING MATERIALS, 2018) Yazman, Şakir; Gemi, Lokman; Uludağ, Muhammet; Akdemir, Ahmet; Uyaner, Mesut; Dışpınar, Derya
In this work, macrostructure, microstructure, and work hardening of as-cast and austempered ductile iron chips produced by different cutting speeds were investigated. Cutting forces, surface roughness, and tool wear were also studied. After austenitizing at 900 degrees C for 90 min, samples were austempered in a salt bath at 360 degrees C for 90 min. Machinability tests were conducted with uncoated cemented carbide tools on a CNC lathe. The tests were carried out without using any lubricant. In these tests, the cutting speed was varied in the range 50-200 m/min, while the feed rate (0.12 mm/rev) and depth of cut (2 mm) were kept constant. The tangential, feed, and radial cutting force components acting on the tool holder were measured with a three-component dynamometer. The chips obtained during machining were polished by embedding into epoxy resin, examined with optical microscope and micrographs were taken. The microhardness values were measured on each chip sample. As the cutting speed was increased, deformation strengthening of the microstructure was increased, which decreased the tool life. It was also detected that during the machining, with the effect of cutting forces and stress, spheroidal graphites were broken off in the chip and lost their sphericity, so the chip became fragile and unstable and the graphite displayed a lubricant feature. At low cutting speed, a built-up edge was observed. However, as the cutting speed was increased because of heating, built-up edges were unstable.
Doğalgaz Isıtma ve Sıhhi Tesi̇sat Teknoloji̇si̇ Programı Öğrenci̇leri̇ni̇n Endüstri̇ye Dayalı Öğreti̇m Hakkındaki̇ Görüşleri̇ ve Beklenti̇leri̇
(Selçuk Üniversitesi, 2011 Mayıs) Kara, Memduh; Uyaner, Mesut
Bu çalışmada Doğalgaz Isıtma ve Sıhhi Tesisat Teknolojisi Programı öğrencilerinin Endüstriye Dayalı Öğretimden neler bekledikleri, beklentilerinin karşılanma düzeyleri ve karşılaştıkları sorunlar ele alınmıştır. Araştırma kapsamına giren 1. sınıf ve 2. sınıf öğrencilerine anket uygulanmıştır. Araştırma sonucuna göre; işletme yetkilileri öğrencilerin kişisel becerilerine katkı sağlamaktadır. Endüstriye Dayalı Öğretim öğrencilerin kişisel gelişimine büyük bir etkisi olmaktadır ancak süresinin arttırılması gerekmektedir. Öğrencilerin iş yerinde kazandığı beceri okuldakine oranla daha fazladır. Öğrenciler okulda göremediği makine ve aletleri işletmede görmekte ve kullanabilmektedir. İşletme öğrencinin gelecekle ilgili iş bulma kaygısına tam olarak cevap verememektedir.
Dynamic response of laminated composites subjected to low-velocity impact
(SAGE PUBLICATIONS LTD, 2007) Uyaner, Mesut; Kara, Memduh
The dynamic response of E-glass/epoxy composite laminates under low velocity impact was experimentally investigated. Uni-directionally reinforced E-glass/epoxy laminates with the stacking sequence of [0 degrees/-45 degrees/45 degrees/0 degrees/90 degrees/0 degrees/45 degrees/-45 degrees/0 degrees](s) were studied with the aim of an impact test. The impact tests performed at impactor mass (30 kg) for three different impact velocities (2.0, 2.5, and 3.0 m/s) were conducted with a specially developed vertical drop weight testing machine. The radius of the impactor with a semispherical nose was 12 mm. Sample plate specimens that had dimensions of 180 x 50, 180 x 100, and 180 x 150 mm were clamped from two opposite sides while the other two sides were free. The center of each plate was exposed to impact loading. The differences in the impact responses of specimens with varying width are characterized. Moreover, it was shown that the peak force increased with the increase of the width of the specimen.
E-CAMI/EPOKSİ KOMPOZİT BORULARIN DARBE CEVABINA VURUCU GEOMETRİSİNİN ETKİSİ
(2016) Uyaner, Mesut; Kara, Memduh
Bu çalışmada filaman sarım yöntemiyle üretilmiş 55 sarım açısına sahip 10 tabakalı E-camı/epoksi kompozit boruların düşük hızlı darbe cevabına vurucu geometrisinin etkisi deneysel olarak araştırılmıştır. V yatağı üzerine yerleştirilen kompozit boru numunelerine düşük hızlı darbe cihazı kullanılarak, 24 mm ve 12 mm çaplı yarı-küresel ve 120 piramit uca sahip vurucularla düşük enerjili darbe yapılmıştır. Düşük enerjili darbe deneyleri 5 J, 10 J ve 15 J enerji seviyelerinde yapılmıştır. Vurucu geometrisine ve enerji seviyesine bağlı olarak elde edilen kuvvet-zaman ve kuvvet yer değiştirme değişimleri incelenmiştir. Ayrıca farklı geometrilere sahip vurucuların kompozit boru numunesinde meydana getirmiş olduğu hasarlar haritalanmış, vurucu geometrisine bağlı olarak değişen hasar alanları tetkik edilmiştir
THE EFFECT OF BUILD UP EDGE FORMATION ON THE MACHINING CHARACTERISTICS IN AUSTEMPERED FERRITIC DUCTILE IRON
(AMER SOC MECHANICAL ENGINEERS, 2013) Yazman, Sakir; Akdemir, Ahmet; Uyaner, Mesut; Bakircioglu, Bari
In this study, chip formation mechanism during the machining of austempered ferritic DI and the effect of the emerging chip morphology on such machining properties as surface roughness and cutting forces has been scrutinized. After austenitizing at 900 degrees C for 90 min, DI specimens were austempered in a salt bath at 380 degrees C for 90 min. Chip roots were produced by using a quick stop device during the machining of austempered specimens in different cutting speeds. The metallographies of these specimens were performed and chip morphologies were examined. The fact that the cutting speed increased led to a decrease in built-up edge formation. Depending on this fact, it was detected that the change in built-up edge thickness substantially affected the surface roughness and cutting forces. It was also detected that during the machining, with the effect of cutting forces and stress, spheroidal graphites were broken off in the chip and lost their sphericity and so that the chip became fragile and unstable and grafites here displayed a lubricant feature.
Effect of non-penetrating impact damages of pre-stressed GRP tubes at low velocities on the burst strength
(ELSEVIER SCI LTD, 2014) Kara, Memduh; Uyaner, Mesut; Avci, Ahmet; Akdemir, Ahmet
In this study, failure behavior of pre-stressed Glass Fiber Reinforced Plastic (GRP) tubes subjected to low velocity impact was investigated. Filament wound E-glass/epoxy composite tubes with a winding angle of +/- 55 degrees were used in the experiments. The tubes pre-stressed to 32 bars internal pressure, one of the specified operating pressures according to ANSI/AWWA C950 standards. Both prestressed and non-prestressed GRP tubes were subjected to low velocity impact tests at 5, 10 and 15 J low energy levels. Plots of contact force and internal pressure with respect to time and those of force-displacement were obtained and damages occurred on the specimens were examined by means of reflected and transmitted light photography and light microscope. No marked fiber breakages are observed; however, debonding and some sort of delamination on the layers were observed. The GRP tubes with impact damages were subjected to monotonic burst pressures up to failure based on the ASTM D 1599-99 standards. Burst damages on the tubes were studied and variations of their corresponding burst strengths were spotted. Besides that, diameter changes with internal pressures were determined during the tests. Diameter changes with internal pressures for the impacted and the non-impacted tubes were found to be the same. (C) 2014 Elsevier Ltd. All rights reserved.
The Effects of Cutting Speed and Depth of Cut on Machinability Characteristics of Austempered Ductile Iron
(ASME-AMER SOC MECHANICAL ENG, 2012) Akdemir, Ahmet; Yazman, Sakir; Saglam, Haci; Uyaner, Mesut
Ductile iron can acquire enhanced thermal and mechanical properties from austempering heat treatment. The present study aims to identify the function of different cutting parameters affecting machinability and to quantify its effects. Turning was performed to test machinability according to the ISO3685-1993 (E) standard. After austenitizing at 900 degrees C for 90 min, austempered ductile iron (ADI) specimens were quenched in a salt bath at 380 degrees C for 90 min. The cutting force signals along three directions were measured in real time, whereas flank wear and surface roughness were measured offline. For the cutting parameters, the cutting speed and depth of cut were varied, but the feed rate was kept constant. In the flank wear tests, machining length was corresponded to tool life. In addition, in order to find out the effect of cutting parameters on surface roughness (R-a), tangential force (F-t), and flank wear (VB) during turning, response surface methodology (RSM) was utilized by using experimental data. The effect of the depth of cut on the surface roughness was negligible but considerable in the cutting forces. The increased cutting speed produced a positive effect on surface roughness. It is found that the cutting speed was the dominant factor on the surface roughness, tangential force, and flank wear. [DOI:10.1115/1.4005805]
Elastic-Plastic Stress Analysis in a Thermoplastic Composite Cantilever Beam Loaded by Bending Moment
(Sage Publications Ltd, 2002) Sayman, Onur; Uyaner, Mesut; Tarakçıoğlu, Necmettin
In this study, an elastic-plastic stress analysis is carried out in a thermoplastic composite cantilever beam loaded by a bending moment at the free end. The composite beam is reinforced unidirectionally by steel fibers at 0, 30, 45, 60, and 90 orientation angles. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli-Navier hypotheses. It is found that the intensity of the residual stress component of sigma(x) is maximum at the upper and lower surfaces or at the boundary of the elastic and plastic regions. The composite material is assumed to be as hardening linearly. The Tsai-Hill theory is used as a yield criterion.
Elastic-Plastic Stress Analysis of Composite Beams Loaded by Bending Moment
(Sage Publications Ltd, 2002) Sayman, Onur; Uyaner, Mesut; Dağhan, Behçet
An elastic-plastic stress analysis is carried out in a thermoplastic composite cantilever beam loaded by a bending moment at the free end. The orientation angle is chosen as 0degrees, 15degrees, 30degrees and 45degrees. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli-Navier hypotheses. It is found that the intensity of the residual stress component sigma(x) is maximum at the upper and lower surfaces. The beam material is assumed to be strain-hardening. The Tsai-Hill theory is used as a yield criterion. The displacement components are found in the elastic region.
Experimental study of the impact behavior of laminated composites stricken by sharp impactors
(WALTER DE GRUYTER & CO, 2012) Uyaner, Mesut; Kara, Memduh
In this study, the influence of the impactor shape on the dynamic response of E-glass/epoxy laminates was investigated. Composite samples were impacted using steel 90 degrees and 120 degrees conical, 24 mm and 12 mm in diameter hemispherical, pyramidal impactors via a specially developed drop weight test machine. The impact tests were performed at impactor mass (20 kg) for impact velocity (2.5 m/s). Plate specimens consisting of 18 plies for tests (180x50 mm) with a nominal thickness (7 mm) were used. Contact force-time and contact force-deflection data obtained from the experiments were interpreted. It was found that the contact force was smaller in the 90 degrees conical impactor while it was bigger in the 24 mm hemispherical one. Absorbed energies were also investigated. The absorbed energy obtained for pyramidal impactor was greater than that of the others. Furthermore, overall damage areas caused by the impactor were evaluated.
Fatigue behavior of filament wound E-glass/epoxy composite tubes damaged by low velocity impact
(ELSEVIER SCI LTD, 2014) Uyaner, Mesut; Kara, Memduh; Sahin, Aykut
In this paper, filament wound glass fiber reinforced plastic (GRP) tubes were studied. Impact tests were realized at 5 J and 10 J energy levels. Force-time and force-displacement curves were obtained and damage zones were also examined. The burst strengths of tubes were found in accordance with ASTM-D 1599 before and after impact. For fatigue tests, PLC controlled hydraulic inner-pressure fatigue test rig was set up. Damaged and non-damaged tubes were subjected to the fatigue test in accordance with ASTM-D 2992. The samples were exposed to five different stress levels; 30%, 35%, 40%, 50%, 60% of the burst strength. Number of cycles occurred up to the final failure was recorded and S-N diagrams were plotted. The burst strength and the fatigue life of the damaged GRP pipes were decreased as the impact energy increased. Also the decrease in the fatigue life was greater than that of the burst strength. (C) 2013 Elsevier Ltd. All rights reserved.
Filaman sarım ile üretilen CTP kompozit borularda tabaka sayısının teğetsel gerilme dayanımına etkisi
(2017) Kara, Memduh; Uyaner, Mesut
Cam takviyeli plastik (CTP) kompozit boruların diğer boru çeşitlerine göre birçok üstün özelliği vardır. Bunlar, kimyasal maddelerin oluşturacağı korozyona karşı dayanım, olumsuz hava koşullarına ve UV ışınlara karşı dayanım, istenilen boyutlarda seri üretim imkânı ve uzun ömürlü olması gibi özelliklerdir. Bütün bu özellikleri nedeniyle petrol ve doğalgaz iletim hatlarında ve kimyasal akışkanların iletim hatlarında yaygın olarak kullanılmaktadır. Kullanım alanı hızla artmakta olan CTP kompozit boruların mekanik özelliklerinin belirlenmesi için birçok test yöntemi geliştirilmiştir. Cam takviyeli plastik boruların teğetsel gerilme dayanımı; ASTM D 1599 standardına göre hidrolik basınç testi ve ASTM D 2290 standardına göre halka çekme testi ile tespit edilmektedir. Bu çalışmada 6, 8 ve 10 tabakalı olacak şekilde filaman sarım yöntemiyle 55 sarım açısında üretilen Ecamı/epoksi kompozit boruların teğetsel gerilme dayanımı her iki yöntem kullanılarak belirlenmiştir. Her iki yöntemden elde edilen sonuçlar birbirleriyle karşılaştırılarak değerlendirilmiştir. Ayrıca CTP kompozit borularda statik iç basınç patlatma testi esnasında ve halka çekme testi esnasında oluşan hasar gelişimi değerlendirilmiştir.
Filaman sarım kompozit boruların düşük hızlı darbe davranışının simülasyonu
(Selçuk Üniversitesi Mühendislik-Mimarlık Fakültesi, 2011) Uyaner, Mesut; Güvensoy, Serdar
Bu çalışmada düşük hızlı darbeye maruz E-camı/epoksi filaman sarım kompozit boruların dinamik cevabı araştırılmıştır. Uygulanacak yöntem Sonlu Elemanlar Yöntemi olup bu çalışma bilgisayar analizi sonuçlarının yorumlanmasına dayanmaktadır. Filaman sarım kompozit boru ve darbe olayı modellenmiştir. Benzeşim için ANSYS-LSDyna ticari yazılımı kullanılmıştır. Benzeşimde kullanılacak vurucu 24 mm çapında, küresel uçlu bir geometriye sahiptir. Vurucu kütlesi 6,35 kg’ dır. İnceleme 2, 2,5 ve 3 m/s’lik çarpma hızlarında yapılmıştır. Çalışmalarda [+55°,?55°]3, [+55°,?55°]4, ve [+55°,?55°]5 olmak üzere 6, 8 ve 10 tabakalı E-camı/epoksi malzemeden 72 mm iç çapında, bir V-yatağında dönmeden durabilen kompozit borular kullanılmış ve her bir borunun enine darbe yapılmıştır. Elde edilen bu veriler doğrultusunda, malzeme üzerine darbe esnasındaki kuvvet-zaman diyagramı, darbe enerjisi-yutulan enerji değişimi, hız-zaman değişimi grafikleri elde edilmiştir.
IMPACT RESISTANCE OF GYPSUM BOARD SUBJECTED TO LOW VELOCITY IMPACT
(UNIV OSIJEK, TECH FAC, 2017) Kara, Memduh; Metinoz, Mufit; Uyaner, Mesut
The aim of this study was to investigate the impact resistance and damage behaviour of gypsum and composite gypsum boards subjected to low velocity impact. Low velocity impact tests were performed on four different board materials which can be listed as gypsum boards, gypsum+75 gr/m(2) mesh boards, gypsum+wallpaper boards and gypsum+75 gr/m(2) mesh+wallpaper boards. Indenter used in the impact tests was 24 mm in diameter and has semi spherical tip geometry. Gypsum and composite gypsum boards were bonded in 500x400 mm sizes and simply supported at four sides. Various energy levels, i.e. 2, 4, 6, 8, 10 and 12 J were applied to the centre of each board. As a result of low speed impact tests, impact force-time and force-displacement variations were obtained and the damaged regions of the samples were examined. Penetration thresholds and perforation thresholds of gypsum and composite gypsum board samples were determined by using Energy Profile Method (EPM). The effect of adding mesh and wallpaper into the gypsum board on stab and puncture limits was evaluated. Around 62.40 % increase occurred on gypsum+mesh+wallpaper board comparing to gypsum board in perforation thresholds.
Low velocity impact response of CFRP and Al2024-T3 helicopter blade
(Selçuk Üniversitesi, 31.12.2024) Kurtar, Sakine; Yaman, Gamze; Bektaş, Dilara Nur; Özsunar, Seda Nur; Uyaner, Mesut
A high level of safety is demanded in response to the foreign object damage (FOD) problem frequently encountered in aviation. For this reason, in this study, the effect of stone impact on a helicopter blade performed within the scope of FOD is investigated. Considering the actual size of the propeller, a stone impact is applied to a certain section and the mechanical behavior of the propeller is examined according to the material type. In this direction, the Bo-105 helicopter blade with the NACA-23012 profile is taken as a reference, and a 3D drawing of the blade is made in the SolidWorks program. The behavioral properties of metal and composite materials frequently preferred in aviation against stone impact are compared. For this purpose, Al2024-T3 and carbon fiber reinforced polymer (CFRP) are selected. These materials are frequently preferred in aviation. To observe the difference between the materials, low-velocity impact analysis is performed on two blade sections with span dimensions of 140 mm and chord dimensions of 310 mm under the same geometry and conditions. The analysis of the simulated action is obtained using the LS-DYNA program. Because it is a mechanical action, the Arbitrary Lagrangian (ALE) method was used accordingly. Within the scope of this method, the stone to be hit by the blade was modeled as a 5 mm solid structure and hit the blade surface with a speed of 3500 mm/s. While the blade with Al2024-T3 material was modeled as a shell, the CFRP blade was modeled as a composite part consisting of six layers at [0-90-0-90-0-90] degrees. Material properties were defined on the blade using 018 Law Plasticity and 54/55 Enhanced Composite Damage material cards for Al2024-T3 and CFRP, respectively. As a result of this analysis, the time-dependent changes in displacement, kinetic energy, and force parameters were acquired. Then, the low-velocity impact responses of the CFRP and the Al2024-T3 blades were compared.
Metal tabakalı kompozitlerin düşük hızlı enine darbeye karşı davranışlarının incelenmesi
(Selçuk Üniversitesi Mühendislik Fakültesi, 2016) Kara, Memduh; Uyaner, Mesut
Bu çalışmada metal kompozit levhaların düşük hızlı enine darbe davranışları incelenmiştir. 1 mm kalınlığında St37 DKP çelik ve 1050-H14 alaşımlı alüminyum plakalar kullanılarak dört farklı yerleşim düzeninde oluşturulan üç katmanlı kompozit levhalar farklı enerji seviyelerinde düşük hızlı darbe testlerine maruz bırakılmışlardır. 150x150 mm ebatlarında kesilen metal levhalar üç alüminyum, üç çelik, aliminyum+çelik+alüminyum ve çelik+alüminyum+çelik olacak şekilde dizilerek dört tarafı ankastre olacak şekilde bağlanmıştır. Deneylerde kullanılan vurucu kütlesi 6,35 kg olup 24 mm yarı küresel geometriye sahiptir. Hazırlanan her bir deney numunesinin ortasına 10J, 20J, 30J, 40J ve 50J enerji seviyelerinde darbe testleri yapılmıştır. Darbe testleri sonucu elde edilen kuvvet-zaman, hız-zaman ve kuvvet-yer değiştirme değişimleri grafikler halinde incelenmiştir. Her bir deney numunesinde meydana gelen hasarların boyutları ve hasar şekilleri değerlendirilmiştir
Plastic Zones for a Penny-shaped Crack in a Transversely Isotropic Layer Bonded Between Two Isotropic Half Spaces
(GAUTHIER-VILLARS/EDITIONS ELSEVIER, 2002) Uyaner, Mesut; Ataberk, Necati; Avcı, A.
In this paper, a problem in an elastic-perfectly plastic dissimilar layered medium is considered. It is assumed that a transversely isotropic layer is sandwiched between two isotropic semi-infinite half spaces, and contains a penny-shaped crack located in its mid-plane. The problem is formulated by using integral transform technique under uniform load and reduced to a singular integral equation. This integral equation is solved numerically by using Gaussian Quadrature Formulae. The plastic zones are evaluated by using the plastic strip model. They are plotted for various penny-shaped crack sizes and transversely isotropic materials. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

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