Person: YILMAZ, TUFAN GÜRKAN
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YILMAZ
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TUFAN GÜRKAN
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Publication Effects of drive side pressure angle on gear fatigue crack propagation life for spur gears with symmetric and asymmetric teeth(Amer Soc Mechanical Engineers, 2020-01-01) KARPAT, FATİH; DOĞAN, OĞUZ; Yılmaz, Tufan; YILMAZ, TUFAN GÜRKAN; Yüce, Celalettin; YÜCE, CELALETTİN; KARPAT, ESİN; KOPMAZ, OSMAN; Kalay, Onur Can; Mühendislik Fakültesi; Mekatronik Mühendisliği BölümüToday gears are one of the most crucial machine elements in the industry. They are used in every area of the industry. Due to the high performances of the gears, they are also used in aerospace and wind applications. In these areas due to the high torques, unstable conditions, high impact forces, etc. cracks can be seen on the gear surface. During the service life, these cracks can be propagated and gear damages can be seen due to the initial cracks. The aim of this study is to increase the fatigue crack propagation life of the spur gears by using asymmetric tooth profile.Nowadays asymmetric gears have a very important and huge usage area in the industry. In this study, the effects of drive side pressure angle on the fatigue crack propagation life are studied by using the finite element method. The initial starting points of the cracks are defined by static stress analysis. The starting angles of the cracks are defined constant at 45 degrees. The crack propagation analyses are performed in ANSYS SMART Crack-Growth module by using Paris Law. Four different drive side pressure angles (20 degrees-20 degrees, 20 degrees-25 degrees, 20 degrees-30 degrees and 20 degrees-35 degrees) are investigated in this study. As a result of the study the fatigue crack propagation life of the gears is increased dramatically when the drive side pressure angle increase. This results show that the asymmetric tooth profile not only decrease the bending stress but also increase the fatigue crack propagation life strongly.Publication Experimental verification and finite element analysis of automotive door hinge(Amer, 2015-01-01) Doğan, S.; Güven, C.; Karpat, Fatih; Yılmaz, Tufan Gürkan; Doğan, Oğuz; ASME; KARPAT, FATİH; YILMAZ, TUFAN GÜRKAN; DOĞAN, OĞUZ; Mühendislik Fakültesi; Makine Mühendisliği; 0000-0001-8474-7328; 0000-0003-3772-7871; 0000-0003-4203-8237; V-6153-2017; A-5259-2018; GXH-1702-2022; AAV-7897-2020; CTF-4189-2022; EVY-7464-2022In automotive industry, achieving lightweight, low-cost, reliable and more accurate product design are the most important goal. Using Finite Element Analysis (FEA) is an important tool for achieving this since it decreases prototyping cost and time. Cars have different door system and one of the important part of them is door hinge. An automotive door hinge is mainly composed of three elements, fixed part, mobile part and hinge pin that fasten fixed part and mobile parts. Manufacturers have to perform tests and analysis for ensuring international and customer requirements.In this study, FEA results are compared with static and dynamic test results of front door hinge of automotive according to International specifications. The agreement between the computed and measured values is shown.Publication A comparative experimental study on the impact strength of standard and asymmetric involute spur gears(Elsevier, 2021-01-06) Kalay, Onur Can; Doğan, Oğuz; Yılmaz, Tufan Gürkan; Yüce, Celalettin; Karpat, Fatih; Kalay, Onur Can; YILMAZ, TUFAN GÜRKAN; KARPAT, FATİH; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0001-8643-6910; 0000-0003-3772-7871; 0000-0001-8474-7328; GDQ-4936-2022; V-6153-2017; A-5259-2018Gears are one of the main components of the power transmission systems and are used in various fields. Problems caused by sudden load changes in mobile systems are frequently encountered today. Gear dynamics have become more influential due to demands of high power transmission capability, long life, and low-cost. However, inertial forces caused by accelerated movements of gear can have unpredictable results. The impact loads must be calculated correctly. It is inconvenient to determine the impact strength of gear via standard drop-weight test rig due to inhomogeneity and complex geometries. This study investigates how the tooth profile affects the impact load on the involute spur gears. For this reason, a special test setup and experimental approach was proposed to examine the influence of the asymmetric profile on the impact strength. It was observed that the peak force values increased by approximately 15.3% when using 20/30 degrees asymmetric profile gears in comparison with the 20 degrees/20 degrees standard design. This improvement can reach up to 25.8% in terms of peak force energy. The results indicate that the proposed novel test setup and the experimental method can be used for measuring the impact strength of asymmetric involute gears.Publication Design and analysis of internal gears with different rim thickness and shapes(Amer Soc Mechanical Engineers, 2016-01-01) Karpat, F.; Ekwaro-Osire, S.; Yılmaz, T. G.; Doğan, O.; Yüce, C.; KARPAT, FATİH; YILMAZ, TUFAN GÜRKAN; DOĞAN, OĞUZ; YÜCE, CELALETTİN; Mühendislik Fakültesi; Makina Mühendisliği Bölümü; 0000-0001-8474-7328; 0000-0003-4203-8237; 0000-0003-1387-907X; GXH-1702-2022; AAV-7897-2020; V-6153-2017; R-3733-2017; A-5259-2018In recent years, thanks to their significant advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations, internal gears have been used in automotive and aerospace applications especially in planetary gear drives. Although internal gears have a number of advantages, they have not been studied sufficiently. Internal gears are manufactured by pinion type cutters which are nearly identical with pinion gear except the addendum factor which is 1.25 instead of 1. The tip geometry of a pinion type cutter which determines the fillet of internal gear tooth can be sharp or rounded. In this study, the design of internal gears were investigated by using a traditional approach. Mathematical equations of pinion type cutter were obtained by using differential geometry, then the equations of internal gear tooth were derived accurately by using coordinate transformations and relative motion between the pinion type cutter and internal gear blank. A computer program was generated to attain points of internal gear teeth and three dimensional design of complete gear. 20-20 were used as pressure angle. To find optimum internal gear geometry, different rim thicknesses and shapes are tried out for finite element analyses. There were several parameters that were shown to effect the performance of the internal gears, with tooth stiffness being the most significant parameter. Tooth stiffness was also vitally influence the dynamic analysis. In order to compute gear tooth stiffness of the internal gear with various rim thicknesses and shapes, finite element analysis was used. A static analysis was performed to assess the gear bending stress and tooth displacement. Tetrahedral element type was selected for meshing. The internal gear outer ring was fixed and the force of 2500 N was applied on the tooth. According to the displacement values from the analysis internal gear tooth stiffness were calculated individually. Additionally, the effect of root bending stress with varying rim thickness, shapes, and root radius were investigated. The bending stresses were calculated according to ISO 6336 and using finite element analysis were shown to be in good agreement. It was shown that when the rim thickness and fillet radius were increased, the maximum bending stresses decreased considerably. As rim thickness was increased, the maximum bending stress decreased nearly 23%. It was also shown that as the fillet radius decreased, the maximum bending stress increased, whereas the rim stresses slightly changed. As the fillet radius was decreased, the maximum bending stress increased nearly 10%. It was also observed that when rim thickness was increased, the stress on the rim was decreased, whereas tooth stiffness was increased. However, fillet radius had no visible effect both on rim stress and tooth stiffness. Furthermore, it was shown that the rim shape had significant effect on rim stress.Publication Stress analysis of additive manufactured lightweight spur gears(Amer Soc Mechanical Engineers, 2021-01-01) Ekwaro-Osire, Stephen; Yılmaz, Tufan Gürkan; YILMAZ, TUFAN GÜRKAN; Kalay, Onur Can; Karpat, Fatih; KARPAT, FATİH; Mühendislik Fakültesi; 0000-0003-3772-7871; 0000-0001-8643-6910; 0000-0001-8474-7328; 0000-0002-9548-8648; V-6153-2017; A-5259-2018Additive manufacturing processes (AMP) have grown and spread in the last twenty years. Additive manufacturing methods, which were first used for plastic materials, are now increasingly finding a place in metals. With these methods, more lightweight component designs which cannot be generated with traditional methods can be manufactured. With the spreading of electric drive vehicles, weight reduction is becoming more important since weight is primarily responsible for energy consumption. There is a one-stage gear system in electric vehicles in general. For this reason, the subject of reducing the mass of gears is gaining importance. The weight reduction can be achieved with holes and slots on the gear body for involute spur gears or reducing gear web thickness. Several optimization methods can be used for this aim. Another way is to use light materials for the gear body, while steel material is used in the tooth-rim region. Carbon fiber composites are preferred for this purpose. However, using adhesives to join steel and carbon fiber reinforced plastics may cause problems in different environmental conditions. On the other side, parts are generated with single material with AMP methods. In this study, involute spur gears with different designs convenient for generation by AMP are created in a 3D CAD program. The involute tooth region is defined as design space. The effects of different designs on root stress and tooth stiffness are investigated by finite element analyses. For this purpose, the mathematical modeling of involute spur gear is set to get points of a tooth based on Litvin's approach in MATLAB. A point cloud code is obtained and imported to the 3D CAD program. After that, three teeth 3D finite element spur gear models are generated. Static analyses are conducted in ANSYS. Meshing force is implemented on the highest point single tooth contact line. Root stress value is the most important reason for tooth root fatigue, one of the most common failure modes of involute spur gears. Tooth deflection and stiffness are significant parameters for the dynamic behavior of involute spur gears. The tooth stiffness affects mesh stiffness and transmission error which are the primary source of gear whine. For these reasons, tooth root stress and tooth deflection values should be determined for different gear designs.In this study, stress analyses of additive manufactured gears are conducted with the finite element method. The effect of shell thickness, infill radius, and infill stiffener on tooth root stress and deformation is recorded. According to the results, shell thickness is the most effective parameter on the root stress and deformation. It is followed by infill orientation angle and infill radius, respectively.Publication An investigation on the design of formate and generate face milled hypoid gears(Amer Soc Mechanical Engineers, 2020-01-01) Doğanlı, Mert; Altıntaş, Elif; Yılmaz, Tufan Gürkan; YILMAZ, TUFAN GÜRKAN; Kalay, Onur Can; Karpat, Fatih; KARPAT, FATİH; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0003-3772-7871; 0000-0001-8643-6910; 0000-0001-8474-7328; A-5259-2018Hypoid gears are transmission elements that transfer power and moment between shafts whose axes do not intersect. They are similar in structure to spiral bevel gears. However, there are many advantages compared to spiral bevel gears in terms of load carrying capacity and rigidity. Hypoid gear pairs are mostly used as powertrain on the rear axles of cars and trucks. Hypoid gears are manufactured by two essential methods called face-milling and face-hobbing, and there are mainly two relative kinematic movements (Formate (R) and Generate). In this study, the gears produced with the Face-milling method are discussed. Face milled hypoid gears can be manufactured with both Formate (R) and Generate, while pinions can only be manufactured with the Generate method. The most crucial factor that determines the performance of hypoid gears is the geometry of hypoid gears. The gear and pinion geometry is directly dependent on the tool geometry, machine parameters, and relative motion between the cradle and the workpiece. The gear geometry determines the contact shape and pressure during power transmission. In this study, the mathematical equation of the cutting tool is set. After that, using differential geometry, coordinate transformation, and the gearing theory, the mathematical equation of hypoid gear is obtained.Publication Effects of rim thickness on tooth root stress and mesh stiffness of internal gears(Amer Soc Mechanical Engineers, 2015-01-01) Yilmaz, Tufan; YILMAZ, TUFAN GÜRKAN; Yüce, Celalettin; YÜCE, CELALETTİN; Karpat, Fatih; KARPAT, FATİH; Engin, B.; Doğan, O.; DOĞAN, OĞUZ; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0001-8474-7328; 0000-0003-4203-8237; 0000-0003-1387-907X; 0000-0003-3772-7871; A-5259-2018; GXH-1702-2022; R-3733-2017; AAV-7897-2020; V-6153-2017In recent years, internal gears are used commonly in a number of automotive and aerospace applications especially in planetary gear drives. Planetary gears have many advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations. Although internal gears have many advantages, there are not enough studies on it. Designing an internal gear mechanism includes two important parameters. The gear mesh stiffness which is the main excitation source of the system. In this paper, 2D gear models are developed in order to compute gear mesh stiffness for various rim thicknesses and different rim shapes of the internal gear design. Effects of root stress with varying rim thickness and some tooth parameters are investigated by using 2D gear models. The stress calculated according to ISO 6336 and the stresses calculated against FEM are compared. These results are well-matched. It is observed that when the rim thicknesses are increased, both the maximum bending stresses and gear mesh stiffness are decreased considerably.Publication Improvement of loading capacity of internal spur gear with using asymmetric trochoid profile(Amer Soc Mechanical Engineers, 2018-01-01) Yılmaz, Tufan Gürkan; Doğan, Oğuz; Yüce, Celalettin; Karpat, Fatih; ASME; YILMAZ, TUFAN GÜRKAN; DOĞAN, OĞUZ; YÜCE, CELALETTİN; KARPAT, FATİH; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0003-3772-7871; 0000-0003-4203-8237; 0000-0003-1387-907X; 0000-0001-8474-7328; R-3733-2017; A-5259-2018; GXH-1702-2022; V-6153-2017; AAV-7897-2020Today, with numerous advantages such as reduced sliding velocity and wear, higher transmission ratio, higher running efficiency etc., internal spur gears are used in several industrial applications. An internal gear is generated by pinion cutters towards inside of gear blank opposite of external gear. In this study, bending stress of internal spur gear with the asymmetric trochoid profile is investigated. Asymmetry is ensured by using pinion cutter has different tip radius value on its right and left side. This situation is allowed to use larger tip radius on one side. The limit value of tip radius is defined with taking into account cutter addendum height and interference possibility for the given pinion gear parameters. On the other side, asymmetry on the involute region is also examined. Firstly, a mathematical equation of pinion cutter is derived then points of internal gear are obtained by using coordinate transformation, differential geometry and gearing theory in MATLAB. Points of internal gear are exported to CATIA to realize the 3D design. Case studies are conducted for determining the relation between tip radius and pressure angle on bending stress separately with ANSYS program. According to preliminary results, using asymmetric trochoid profile reduces approximately 16% bending stress of internal spur gear.