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Öğe Analysis of scoring resistance on coated spur gears by considering surface roughness(Hitit University, 2017) Tunalıoğlu, Mert Şafak; Gemalmayan, NihatWith the rise of velocity and momentum in machines as a result of technological developments, on gears, alongside refraction from the bottom of the gears and pitting formation, and scoring formation has showed up. In the scoring formation phase because of the fact that many parameters are influential, resistance calculations could not be stated precisely. In experiments made for this purpose, 20MnCr5 steel gears were coated using various coating materials (chrome, nickel and manganese), thus usage of coating material on gear mechanisms in terms of scoring was analyzed. In the experiments, gears were rotated with a speed of 3000 rpm and the oil temperature constant at 323±2 °K. Gears were exposed to loading at 15.2 Nm and continued by increasing 20 % until scoring formation was observed. It is seen in the experiments that coated gears have more scoring resistance than uncoated ones. It is also observed that coating materials increases the scoring strength of gears. According to the experiments, when gears run at the same conditions (speed, torque and lubrication), chrome coated gears are 10 times longer, nickel coated gears are 5 times and manganese coated gears are 1.5 times longer resisted when compared with uncoated gears. After the scoring formation, experiments continued for determining how the scoring formation developed. It is seen in the experiments that when scoring occurs the wear increases rapidly on the tooth of gearsÖğe Effect of coating material on wear in internal gears(Materials and Energy Research Center, 2017) Tunalıoğlu, Mert Şafak; Tuç, Bedri; Erdin, Muhammed EminTheoretical and experimental investigation of wear during coupling in internal gears coated with various polymeric coating materials was performed in this study. In the theoretical part of the study, Archards' wear formulation was adapted to internal gears and wear behavior in various conditions was determined. Moreover, a fatigue and wear testing apparatus having similar working principle with FZG (Forschungsstelle für Zahnrader und Getreibbau) closed circuit power circulation system was designed and manufactured to experimentally investigate the wear in internal gears. Internal gear-pinion couples manufactured from St50 material were coated with various polymeric materials, namely PTFE (polytetrafluoroethylene), MoS2 bonded with polyamide, MoS2 bonded with epoxy in the experimental study. An uncoated internal gear was also investigated to find out the performance of coated gears. Variation of wear depth on tooth profiles of internal gears were determined theoretically and experimentally. Theoretical and experimental studies showed that polymeric coated internal gears have more wear resistance than uncoated ones by means of high lubrication ability and low friction coefficient of coating materials. It was also observed that high corrosion resistance of polymeric coatings protected metallic surfaces and decreased corrosive wear.Öğe Effect of tooth profile modification on wear in internal gears(IOP Publishing Ltd, 2018) Tunalıoğlu, Mert Şafak; Tuç, BedriInternal gears are often used in the automotive industry when two gears are required to rotate in the same direction. Tooth shapes, slippage speeds at the beginning and end of meshing are different according to the external gears. Manufacturing of internal gears is more difficult than external gears. Thus, it is necessary to determine the working conditions and wear behavior of internal gears carefully. The profile modification method in terms of strength and surface tension of the gear mechanism are performed in order to increase the load-carrying capability. In this study, profile modification method was performed in the internal gears to reduce the wear on the teeth. For this purpose, the wear of the internal gears was theoretically investigated by adapting the Archard wear equation to the internal gears. Closed circuit power circulation system was designed and manufactured to experimentally investigate the wear in internal gears. With this system, wear tests of gears made of St 50 material without profile modification and different profile modifications were made and the results were compared. Experimental study was performed in the same loading and cycle time conditions to validate the theoretical results and it was seen that the results are compatible. According to the experimental results, it is seen that in the internal gears, when profile modification done the wear is decreased in the teeth tip region. © Published under licence by IOP Publishing Ltd.Öğe Farklı Tip Uçucu Küllerin Kauçuğun Mekanik Özelliklerine Etkisinin Deneysel İncelenmesi(2020) Tunalıoğlu, Mert ŞafakGünümüzün en önemli sorunlarından bir tanesi de atık malzemelerin doğaya zarar vermeden depolanması veya ortadan kaldırılmasıdır. Termik santrallerde kömürün yakılmasıyla atık bir ürün olan uçucu küller ortaya çıkmaktadır. Uçucu küllerin boyutları genellikle 0.5 ile 200 ?m arasında değişen, camsı yapıya sahip küresel parçacıklardır. Uçucu küller havaya karışıp çevreye zarar vermemesi için çeşitli yollarla toplanırlar. Toplanan uçucu küllerin büyük bir bölümü depolanma yöntemiyle ortadan kaldırılır. Dünyada artan nüfus ile birlikte termik santral kullanımı ve dolayısıyla atık uçucu kül miktarı da artmaktadır. Artan uçucu kül miktarının doğaya zarar vermeden ortadan kaldırılması git gide zorlaşmaktadır. Bu uçucu külleri ortadan kaldırmanın diğer bir yolu da özellikle inşaat ve plastik endüstrisinde ikincil katkı maddesi olarak kullanmaktır. Bu sayede hem uçucu küller kullanıldıkları malzemelere olumlu yönde etki etmekte hem de doğaya zarar vermeden ortadan kaldırılmaktadırlar. Bu amaçla yapılan çalışmada farklı kimyasal özelliklere sahip dört adet uçucu kül SBR(styrene-butadiene rubber) kauçuğa eklenerek, kauçuk üzerindeki mekanik etkileri incelenmiştir. Çalışmada Amerika’nın Teksas Eyaletinde bulunan termik santrallerden Class F, $Micron^3$ , PV 14A ve PV 20A tipi uçucu küller ikincil katkı maddesi olarak kullanılmıştır. Birincil katkı maddesi olarak karbon siyahı kullanılmıştır. Testlerde birincil katkı maddesi olarak karbon siyahı ve %5,10,15,20 oranlarında ikincil katkı maddesi olarak uçucu kül kauçuk malzemeye eklenmiştir. Deneylerde birincil katkı maddesi olarak %100 karbon siyahı eklenerek üretilen kauçuk malzemeler ile farklı oranlarda uçucu kül eklenerek üretilen kauçuk malzemelerin çekme dayanımı ve kopma uzama değerleri karşılaştırılmıştır. Bu şekilde atık ürün olan uçucu küller kullanılarak çevreye olan zararları azaltılmış hem de plastik malzemenin çekme dayanımında ve kopma uzamasında artış sağlandığı gözlenmiştir.Öğe Role of adhesion in sandpaper failure progression(Elsevier Ltd, 2016) Tunalıoğlu, Mert Şafak; Sancaktar, ErolIn this study, different grit sizes of sandpapers were used under controlled rubbing experiments using a rheometer to investigate the role of adhesion in failure progression by particulate separation. Frictional shear forces were induced on sandpaper samples of different grit sizes by frictional rubbing of the same and different grit size sandpaper samples. Comparison of failure rates under different normal forces, grit sizes, as well as grit size mismatch, provided insight on the role of particulate adhesion to the sandpaper's backing sheet on the loss of wear function for different grit-size sandpapers. In conclusion, it is considered that the wear/failure mechanism for the cases corresponding to similar/reasonably close wear ratios are likely to have occurred under similar mechanism, most probably adhesion failure on the abrasive particles. © 2015 Elsevier Ltd. All rights reserved.Öğe Saturation operation on the direct current motor that is used for manipulator control(2013) Gemalmayan, Nihat; Tunalıoğlu, Mert ŞafakIn this study, the saturation operation on the motor armature current has been carried out with a manipulator control algorithm. Manipulator system is controlled by state feedback plus integral error control strategy. Controller design tool in the system is pole placement method. Linearization process was performed by means of Jacobian matrices that expresses small refractions around nominal trajectory of manipulator system. The conclusions for two degree of freedom manipulator were shown with simulations by means of a computer program that makes saturation operation.Öğe The effect of finely-divided fillers on the adhesion strengths of epoxy-based adhesives(Elsevier Ltd, 2015) Tüzün, Fatma Nihal; Tunalıoğlu, Mert ŞafakIt was aimed to investigate the effect of five different fillers on the adhesion strength of the metal parts used in different industries by using T-peel and lap-shear tests with respect to ASTM D 1876 and ASTM D 1002 respectively. EPIKOTE® 828 and DURATEK® epoxy resin types were used as adhesives with curing EPIKURE® 3090 modified polyamidoamine adduct and DURATEK® polyamide curing agents respectively. Curing temperatures were increased, while curing times were decreased. Five different fillers used are calcite with a mean particle diameter of 4.97 ?m, talc extra with an average particle diameter of 4.91 ?m, and barite extra with a mean particle diameter of 4.76 ?m supplied by ESEN MIKRONIZE, calcite with an average particle diameter of 0.7 ?m and coated calcite with a mean particle diameter of 0.9 ?m provided by ERCIYES MIKRON. The effect of five different fillers on adhesion strength was investigated with choosing the best regression model fitted to data by using two different epoxy resin systems. The best values in shear and peel tests were attained with calcite having the particle diameter of 0.7 ?m in both type of epoxy resins providing a good agreement between experimental and theoretical results.Öğe Theoretical and experimental investigation of wear in internal gears(2014) Tunalıoğlu, Mert Şafak; Tunç, BedriInternal gears are commonly used in automotive and aeronautic industries as external sun gears of planetary mechanisms. Internal gears have some advantages such as low sliding velocities, low contact stresses, high contact ratios compared with external gears. Therefore, manufacturing is more difficult than external gears. For this reason, it is necessary to determine the working conditions of internal gears carefully. For that purpose, wear in internal gears is investigated theoretically by adapting Archard's wear equation to internal gears and a MATLAB® programme is written to solve this modified equation. The aim is to determine the wear values in different conditions by using this modified equation. In addition, a fatigue and wear test equipment is designed and manufactured which is similar to FZG (Forschungsstelle für Zahnrader und Getreibbau) closed circuit power circulation system in working principle to investigate wear in internal gears experimentally. Internal spur gears which are manufactured from St50 are used in the experiments with different torques and motor speeds. Wear is determined that occurs in tooth profiles of internal gears for different load cycles. It is seen that the results obtained from theoretical and experimental studies are compatible. © 2013 Elsevier B.V.Öğe Wear and Service Life of 3-D Printed Polymeric Gears(MDPI, 2022) Tunalıoğlu, Mert Şafak; Ağca, Bekir VolkanPlastic gears are mostly used in the textile, food, and automotive industries due to their silent operation, corrosion resistance, and light and cheap advantages. Plastic gears are generally manufactured by injection molding or hobbing methods. The excess costs of the molds used to produce parts in injection molding and the problems of wastes that occur during production in hobbing lead companies to additive manufacturing, which is an alternative application. In the additive manufacturing method, the desired amount of product is produced without the problem of waste. In this study, the wear resistance of plastic spur gears produced by the Fused Deposition Modeling (FDM) method was determined theoretically. In order to determine the service life of gears, wear tests were carried out in the Forschungsstelle fur Zahnrader und Getriebebau (FZG) type test device at the same load and rotational speeds. polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PETG) thermoplastic polymer materials were used in the production of gears. When the gears rotate at the same load and rotational speeds, the most wear was observed in ABS, PLA, and PETG at the theoretically calculated wear depths. PETG is the most resistant material in terms of wear.
