Browsing by Author "Yüce, Celalettin"
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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; Bursa Uludağ Üniversitesi/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.Item A case study: Designing for sustainability and reliability in an automotive seat structure(MDPI, 2014-07-16) Yüce, Celalettin; Karpat, Fatih; Yavuz, Nurettin; Şendeniz, Gökhan; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-8474-7328; 0000-0003-1387-907X; A-5259-2018; R-3733-2017; 56237466100; 24366799400; 6701698986; 56236950000Recently, sustainability has been a growing concern for many industries and especially for the transportation sector due to it being the second largest energy consumer and largest contributor of anthropogenic greenhouse gas emissions within the European Union. New legal restrictions on the emission rates have forced the automotive sector to examine different fuel-efficient technologies. Vehicle weight reduction is one of the most important methods of improving fuel efficiency and reducing CO2 emissions. Accordingly, lighter, safer, more fuel efficient, and environmentally sustainable vehicles are a priority for European authorities. In the present work, the passenger seat structure was considered as the area for lightweighting due to its important role in the mass of commercial vehicles in terms of numbers per vehicle. In addition, seat structures presented the best opportunity for weight reduction using new materials and design techniques. Detailed (3D) finite element models of passenger seats were developed for finite element analyses (FEA). To obtain a lightweight and safe seat structure, different materials and thicknesses of profiles were analyzed. Lightweight passenger seat prototypes were developed and an overall 20% weight reduction was achieved including the structural frame, chassis and pillar. In addition, the new passenger seat meets ECE R14 safety norms.Item Design and development of tractor clutch using combined field and bench tests(Canadian Science Publishing, 2018) Genç, Mehmet Onur; Karpat, Fatih; Yüce, Celalettin; Doğan, Oğuz; Kaya, Necmettin; Uludağ Üniversitesi/Mühendislik Mimarlık Fakültesi/Makine Mühendisliği Bölümü.; 0000-0002-8297-0777; 0000-0003-4203-8237; 0000-0001-8474-7328; 0000-0003-1387-907X; R-4929-2018; GXH-1702-2022; AAV-7897-2020; A-5259-2018; R-3733-2017Tractors, the primary component of agricultural mechanization, are actively used for maintaining agricultural activities and carrying burdens on agricultural fields under challenging conditions. Tractors are not only required to possess a high tractive force at low operating speeds but also to produce the power necessary for operating the equipment attached to them when used for agricultural purposes. It is of great importance to determine the degree of force that powertrains, especially the clutch, of the tractors are exposed to on agricultural fields and to use the data obtained in this process concerning their guarantee periods. This study measured the motor rotation speed, clutch surface temperature, and frequency and force of pushing the clutch pedal of a tractor used under five different agricultural field conditions. Furthermore, torque and transfer of the dynamometer and power take-off (PTO) were measured. Based on the data obtained from field tests, the tractor clutch development and validation processes were revised. The prototype clutch was produced and tested by completing the required 1 million rotations safely under new boundary conditions within the guarantee period.Item The effect of process parameters on the microstructure and mechanical performance of fiber laser-welded AA5182 aluminium alloys(Assoc Mechanical Engineers Technicians Slovenia, 2017) Tekin, Gökhan; Yüce, Celalettin; Tutar, Mümin; Karpat, Fatih; Yavuz, Nurettin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makina Mühendisliği Bölümü.; 0000-0002-7286-3433; 0000-0001-8474-7328; 0000-0003-1387-907X; J-2753-2016; A-5259-2018; R-3733-2017; 56237466100; 54406234300; 24366799400; 6701698986The laser welding of aluminium alloys is an important industrial technology but many challenges remain. The objective of this research is to investigate the effect of laser welding parameters on the quality of the fiber laser lap welded AA5182 aluminium alloy. The influences of the laser power, welding speed and focal point position on the mechanical and microhardness properties of the joints were experimentally investigated. The mechanical properties of the joints were evaluated by performing tensile tests. From the experimental results, optimum process parameters were determined, and microstructural examination and microhardness tests were conducted to better understand the performance of the joints. It was found that there is a correlation between the tensile shear loads of the joints and heat input per unit length. At the optimized parameters, the welded joint showed good weld appearance without macro defects, and the joint had an adequate tensile shear load.Item Effect of rotational speed and dwell time on mechanical properties of dissimilar AA1050-AA3105 friction stir spot welded joints(Walter De Gruyter Gmbh, 2014) Tunçel, Oğuz; Aydın, Hakan; Yüce, Celalettin; Tutar, Mumin; Yavuz, Nurettin; Bayram, Ali; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0002-7286-3433; 0000-0003-1387-907X; 0000-0002-6886-6367; J-2753-2016; R-3733-2017; 16312009400; 56400829400; 56237466100; 54406234300; 6701698986; 7004197848Friction stir spot welding is a newly developed joining technology which is expected to be used in the automotive industry for joining body parts made of aluminum sheets. The effect of the rotational speed and dwell time on the mechanical properties of dissimilar friction stir spot welded aluminum sheet alloys was investigated in this study. In the experimental studies, macro-structural characterization, micro-hardness tests and tensile shear tests were conducted. The experimental results showed that the tensile shear load and tensile deformation of the friction stir spot welded joints decreased roughly by 20 % and 25 %, respectively, when the rotational speed increased from 1000 rpm to 2000 rpm. On the other hand, when the dwell time increased from 3 s to 11 s, the tensile shear load increased roughly by 7 %, while the tensile deformation decreased roughly by 19 %, respectively.Publication Effects of asymmetric tooth profile on single-tooth stiffness of polymer gears(Walter De Gruyter Gmbh, 2022-04-26) Yüce, Celalettin; Doğan, Oğuz; Karpat, Fatih; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi; 0000-0001-8474-7328; A-5259-2018As a result of polymer materials development and the use of additive manufacturing technologies, gear wheels made of polymer materials are becoming widespread in many areas of the industry. In recent years, determining the dynamic behavior of polymer gears has gained significant importance because it is desired to carry more loads and operate at higher speeds. Since it is one of the most critical factors affecting dynamic behavior, tooth stiffness should also be determined. In this study, the single-tooth stiffness (STS) of polymer gears with symmetrical and asymmetrical profile was measured experimentally with a unique test setup. Force was applied to three different points on the tooth, and the resulting deflection was measured with the help of linear variable differential transformer and a high-speed camera. Using the obtained deflection values, STS of the polymer tooth was calculated depending on the pressure angle. The experimental results are also compared with the finite element model created, and it is found that the results are matched well. As a result of the study, it is determined that the drive-side pressure angle of the polymer gear increased from 20 degrees to 32 degrees, and the tooth stiffness increased by approximately 10.8%.Publication Effects of rim thickness and drive side pressure angle on gear tooth root stress and fatigue crack propagation life(Elsevier, 2021-02-12) Doğan, Oguz; Yüce, Celalettin; Karpat, Fatih; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; 0000-0001-8474-7328; A-5259-2018Gears are the most significant machine elements in power transmission systems. They are used in almost every area of the industry, such as small watches to wind turbines. During the power transmission, gears are subjected to high loads, even unstable conditions, high impact force can be seen. Due to these unexpected conditions, cracks can be seen on the gear surfaces. Moreover, these cracks can propagate, and tooth or body failures can be seen. The fatigue propagation life is related to the gear tooth root stress. If the root stresses decrease, the fatigue life of the gears will increase. In this study, standard and non-standard (asymmetric) gear geometries are formed for four different rim thicknesses and four different pressure angles to examine fatigue crack prop-agation life. Moreover, the effects of the rim thickness and drive side pressure angle on the root stress are investigated. The static stress analyses are carried out to determine the starting points of the cracks, and the maximum point of the stress is defined as the starting point of the cracks. Fatigue crack propagation analyzes are performed for gears whose crack starting points are determined. The static stress analyses are conducted in ANSYS Workbench; similarly, the fatigue propagation analysis is performed in ANSYS smart crack growth. In this way, the directions of the cracks are determined for different rim thicknesses and drive side pressure angles. Besides, the number of cycles and da/dN graphs is obtained for all cases depending on crack propagation. As a result of the study, maximum stress values were decreased by 66%. The fatigue propagation life was increased approximately fifteen times by using the maximum drive side pressure angle and optimum rim thickness.Publication Effects of tooth root cracks on vibration and dynamic transmission error responses of asymmetric gears: A comparative study(Taylor & Francis Inc, 2023-03-03) Doğan, Oğuz; YÜCE, CELALETTİN; Kalay, Onur Can; Yüce, Celalettin; Karpat, Fatih; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makina Mühendisliği Bölümü.; 0000-0001-8643-6910; 0000-0003-4203-8237; 0000-0003-1387-907X; 0000-0001-8474-7328; R-3733-2017; AAV-7897-2020; A-5259-2018Gears are significant machine elements used in various industrial applications. An undetected fault in a gear transmission system may lead to a fatal breakdown and, thus, severe economic losses or even human casualties. From this standpoint, the present study developed a numerical method to detect root crack damages in symmetric and asymmetric involute spur gears. To achieve this end, the single tooth stiffness values were calculated for healthy and cracked (25%-50%-75%-100%) gears, and then the time-varying mesh stiffness was obtained. A six-degree-of-freedom dynamic model of a single-stage gear mechanism was developed to collect vibration and Dynamic Transmission Error (DTE) signals. The efficacy of vibration and DTE responses in fault detection was compared through six statistical indicators. The results indicate that the vibration signals were more effective than DTE in detecting tooth root cracks. It was observed that the statistical indicator changes significantly increase with the increment of the drive side pressure angle from 20 degrees to 30 degrees for the backup ratios where the root crack propagates along the tooth, thus making fault detection easier. The findings could provide significant outputs for a better understanding of the influence of tooth asymmetry on gear dynamics characteristics and early fault diagnosis.Publication Experimental investigation of the impact resistance of involute spur gears(IEEE, 2018-01-01) Doğan, Oğuz; Yüce, Celalettin; Karpat, Fatih; Kalay, Onur Can; IEEE; DOĞAN, OĞUZ; YÜCE, CELALETTİN; KARPAT, FATİH; Kalay, Onur Can; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi; 0000-0003-4203-8237; 0000-0003-1387-907X; 0000-0001-8474-7328; 0000-0001-8643-6910; A-5259-2018; GXH-1702-2022; R-3733-2017; GDQ-4936-2022Gears are the most commonly used power transmission element in today's world. Due to their advantages, gears are widely used in many sectors such as aerospace, space, wind turbines, automotive, etc. In these sectors the moment, speed and power values that need to be transmitted are increasing day by day. Due to the increased power and moment values, gears are exposed to high dynamic, impact loads and they are subject to damage due to these loads. For this reason, the impact resistance of the gears must be determined carefully in the design phase of the gear. In this study, an experimental method for determining impact loads of the gears is developed. A special drop gear impact test setup is designed and manufactured to determine the impact loads on the gear. The test setup works by dropping the load on the gear tooth from a certain height. In this way, the teeth are broken and the impact load, acceleration and displacement values are measured by using special measurement instruments which are attached on the test setup. The effect of surface hardness on impact loads is investigated. Two different gear samples are used in the experiments. It is seen that the surface hardness has great effect on the impact loads of the gears. It has been found that surface hardened gears have much higher impact strength than unhardened gears.Item Experimental measurement and numerical validation of single tooth stiffness for involute spur gears(Elsevier Science, 2020-01) Yüce, Celalettin; Karpat, Fatih; Doğan, Oğuz; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği.; 0000-0001-8474-7328; 0000-0003-4203-8237; A-5259-2018; GXH-1702-2022; 24366799400; 7006415878Dynamic characteristics of the spur gears have become a growing field in recent years, due to the high operating speeds and increased power and torque demands. Tooth stiffness is one of the most influential contributing factors of the dynamic behavior of the gear pairs, which varies continuously during the meshing operation. Therefore, the tooth stiffness of the spur gears must calculate accurately. Generally, to calculate the tooth and mesh stiffness of spur gears, analytical equations are used. In this study, single tooth stiffness of involute spur gear was measured experimentally. A special test rig for this purpose was designed, and an experimental technique was proposed to investigate the effects of drive side pressure angle on the stiffness. The validation process of this study was performed using the finite element method. The experiments were repeated in ANSYS Workbench, and the elastic deformations were calculated. Experimental and numerical results were found to be generally consistent. Results showed that, the single tooth stiffness increase nearly 38% with the increase in drive side pressure angle from 20° to 35°. Single tooth stiffness of gear types manufactured by non-traditional methods, including additive manufacturing and forged bimetallic gears, can be investigated experimentally with this technique.Item Farklı malzemelerden üretilmiş interferans vidaların geometrik boyutlarının tutunma dayanımına etkisinin incelenmesi(Bursa Uludağ Üniversitesi, 2023) Kulaksız, Hakan; Yüce, Celalettin; Bursa Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Konstrüksiyon ve İmalat Anabilim Dalı.; 0000-0003-3484-6891İnterferans vidalar, ACL (Anterior Cruciate Ligament) ve PCL (Posterior CruciateLigament) tamiri, lateral ve medial kolateral ligaman rekonstrüksiyonu, aşil tendonuonarımı, distal biceps tendonu onarımı ve proksimal biseps tendonu onarımı gibi birçoktedavide kullanılmaktadır. Bu vidalar genellikle geçici fiksasyon sağlamak amacıyla kullanılır. Farklı boyutlardave farklı malzemelerden üretilmiş interferans vidaların, üretimi ve geçici fiksasyon içindikkat edilmesi gereken tutunma dayanımları incelenmiştir. Bu çalışma kapsamında, farklı boyutlardaki PEEK malzemeden ve Titanyum alaşımdan(Ti6Al4V) üretilen interferans vidaların kortikal kemik üzerindeki tutunma testiyapılmıştır. Medikal testler için kullanılan köpük dökümü “ASTM F1839” standartlarına uygun bir şekilde üretilmiştir. Çekme testi sonuçları, sonlu elemanlaranalizi ile karşılaştırılmıştır. Yapılan değerlendirmede hatve uzunlukları arttıkça tutunma dayanımının azaldığıgözlemlenmiş olup Titanyum alaşımdan üretilen vidaların PEEK malzemeden üretilenvidalara göre daha yüksek tutunum sağladığı tespit edilmiştir.Item An improved numerical method for the mesh stiffness calculation of spur gears with asymmetric teeth on dynamic load analysis(Sage Puplications, 2017-06-23) Ekwaro, Stephen Osire; Karpat, Fatih; Doğan, Oğuz; Yüce, Celalettin; Uludağ Üniversitesi/Mühendislik Mimarlık Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-8474-7328; 0000-0003-4203-8237; 0000-0003-1387-907X; A-5259-2018; AAV-7897-2020; GXH-1702-2022; R-3733-2017; 24366799400; 7006415878; 56237466100Gears are one of the most crucial parts of power transmission systems in various industrial applications. Recently, there emerged a need to design gear drivers due to the rising performance requirements of various power transmission applications, such as higher load-carrying capacity, higher strength, longer working life, lower cost, and higher velocity. Due to their excellent properties, gears with asymmetric teeth have been designed to obtain better performance in applications. As the rotation speed of the gear transmission increases, the dynamic behavior of the gears has become a subject of growing interest. The most important contributing factor of dynamic behavior is the stiffness of the teeth, which changes constantly throughout the operation. The calculation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. The primary objective of this article is to develop a new approach to calculate gear mesh stiffness for asymmetric gears. With this aim in mind, single tooth stiffness was calculated in the first stage of the study using a finite element method. This study presents crucial results to gear researchers for understanding spur gears with involute asymmetric teeth, and the results will provide researchers with input data for dynamic analysis.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; Bursa Uludağ Üniversitesi/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.Publication Influence of heat input on mechanical properties and microstructure of laser welded dissimilar galvanized steel-aluminum joints(Amer Soc Mechanical Engineers, 2018-01-01) Yüce, Celalettin; Karpat, Fatih; Yavuz, Nurettin; ASME; YÜCE, CELALETTİN; KARPAT, FATİH; YAVUZ, NURETTİN; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makina Mühendisliği Bölümü; 0000-0003-1387-907X; 0000-0001-8474-7328; A-5259-2018; R-3733-2017; GKI-9429-2022The hybrid structures of aluminum-steel have been increasingly used for body-in-white constructions in order to reduce weight and green gas emissions. Obtaining acceptable joints between steel and aluminum required a better understanding of welding metallurgy and their effects on the resultant mechanical properties as well as the microstructure of the joints. In this research, the fiber laser welding of zero-gap galvanized steel and aluminum alloy in an overlapped configuration was carried out. The influence of heat input on the weld bead dimension, microstructural and mechanical properties of the joints was studied. A detailed study was conducted on the effects of the heat input on the penetration depth, weld width and microstructure of the laser welded dissimilar joints by means of an optical microscopy. A scanning electron microscopy with energy dispersive spectroscopy was carried out to determine the atomic percent of the elements for intermetallic compounds (IMC) occurred at the interface of the aluminum and steel. Microhardness measurement and tensile shear tests were conducted to evaluate the mechanical properties of the galvanized steel to aluminum lap joints. The experimental results showed that the penetration depth and weld width increased with the increase of heat input level. However, in order to limit IMC layer thickness and hardness at the surface of the weld seam and aluminum alloy, iron to aluminum dilution should be restricted by limiting the penetration depth. At lower heat input levels, less brittle IMC formation was formed. Consequently, with limited penetration depths at low heat input levels, up to 520 N tensile shear load achieved, with failures located in the interface of the joints.Item Investigations on the microstructure and mechanical properties of laser welded dissimilar galvanized steel–aluminum joints(Springer, 2019-10) Yüce, Celalettin; Karpat, Fatih; Yavuz, Nurettin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-8474-7328; A-5259-2018; GKI-9429-2022; 24366799400; 6701698986In this study, galvanized high-strength steel and aluminum alloy sheets were laser-welded in zero-gap lap joint configuration. In order to determine the influences of the heat input levels, microstructural and mechanical properties of the joints were investigated. The weld bead geometry, microstructure, and intermetallic phases at the interface of welded joints were investigated using an optical microscope and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) at different heat input levels. Mechanical properties and microhardness distribution of the welded joints were examined according to the weld bead dimension. The results revealed that there is a correlation between the weld seam geometry and intermetallic phase formation. At relatively high heat input level, the penetration depth increased, and thick Al-rich intermetallic layer was observed at the interface of the weld seam, which deteriorated the tensile strength of the joint. It has been found that without the need for any additional precaution, the thickness of the IMC layer can be limited to 5–15 μm when the optimum welding parameters were conducted. The experimental results showed that with limited heat input and penetration depths, up to 108.7-N/mm tensile strength could be achieved and fracture initiated at the weld seam–steel interface.Publication Multi-response optimization for laser transmission welding of pmma to abs using taguchi-based topsis method(Sage Publications Ltd, 2023-08-01) Küçükoğlu, Ayça; Yüce, Celalettin; Sözer, İbrahim Emrah; Karpat, Fatih; Küçükoğlu, Ayça; YÜCE, CELALETTİN; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0003-1387-907X; 0000-0001-8474-7328; R-3733-2017; A-5259-2018; FJI-7166-2022Recently, the usage of laser transmission welding (LTW) technology in the automotive industry has been rising for joining thermoplastic parts regarding its superior properties in comparison to other welding technologies. However, specifying the process parameters is a crucial step to obtain satisfactory welding quality for the vehicle parts. In this context, this paper addresses the LTW process of Polimetil metakrilat (PMMA) to Akrilonitril butadien stiren (ABS) materials for the production of taillights in an automotive company and proposes a new multi-response Taguchi-Based TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) method to optimize machining parameters in the laser welding process. In the proposed solution methodology, the main effects of the parameters on different outputs are identified by using the L-16 orthogonal array of the Taguchi method. Regarding the best parameter set for each output, the best parameter set for multi-response is identified by using the TOPSIS method, in which alternatives are evaluated through the interrelated quality measures. To optimize welding process in taillight production, PMMA and ABS samples with the dimensions of 40 mm in width, 85 mm in length, and 2 . 7 mm in thickness are used in the experiments. The samples are welded by using LPKF Twinweld 3D 6000 (R) laser welding machine. For the welding process, laser power, welding speed, and pressure force are taken into account as the input parameters to optimize three responses: weld strength, breaking strain, and weld width. To identify the best process parameter values, the Taguchi Method is initially employed to calculate the main effects of LTW parameters for each output. Then, the TOPSIS method is carried out to evaluate a number of alternative parameter sets generated through the Taguchi results. As a consequence of the TOPSIS ranking scores, the best parameter set that jointly optimizes three outputs of the LTW process is identified for the taillight production as 60 W power, 100 mm / s speed, and 150 N pressure force. Based on the conducted experiments, this parameter setting achieves the highest weld strength, breaking strain level, and above-average weld width. The results of the experiments show that the proposed methodology is capable of optimizing LTW parameters for a multi-response with fewer experiments in the joining of plastic vehicle parts.Item A novel design procedure for tractor clutch fingers by using optimization and response surface methods(Korean Social Mechanical Engineers, 2016-02-06) Şen, Hasan; Doğan, Oğuz; Karpat, Fatih; Yüce, Celalettin; Kaya, Necmettin; Yavuz, Nurettin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0003-4203-8237; 0000-0001-8474-7328; 0000-0002-8297-0777; 0000-0003-1387-907X; GXH-1702-2022; AAV-7897-2020; A-5259-2018; R-4929-2018; R-3733-2017; 7006415878; 24366799400; 56237466100; 7005013334; 6701698986This paper presents a methodology for re-designing a failed tractor transmission component subjected to cyclic loading. Unlike other vehicles, tractors cope with tough working conditions. Thus, it is necessary to re-design components by using modern optimization techniques. To extend their service life, we present a design methodology for a failed tractor clutch power take-off finger. The finger was completely re-designed using topology and shape optimization approach. Stress-life based fatigue analyses were performed. Shape optimization and response surface methodology were conducted to obtain optimum dimensions of the finger. Two design parameters were selected for the design of experiment method and 15 cases were analyzed. By using design of the experiment method, three responses were obtained: Maximum stresses, mass, and displacement depending on the selected the design parameters. After solving the optimization problem, we achieved a maximum stress and mass reduction of 14% and 6%, respectively. The stiffness was improved up to 31.6% compared to the initial design.Item The optimisation of process parameters for friction stir spot-welded AA3003-H12 aluminium alloy using a Taguchi orthogonal array(Elsevier, 2014-11) Tutar, Mümin; Aydın, Hakan; Yüce, Celalettin; Yavuz, Nurettin; Bayram, Ali; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0003-1387-907X; 0000-0002-7286-3433; R-3733-2017; J-2753-2016; 54406234300; 16312009400; 56237466100; 6701698986; 7004197848The aim of the present work is to optimise the welding parameters for friction stir spot welded non-heat-treatable AA3003-H12 aluminium alloy sheets using a Taguchi orthogonal array. The welding parameters, such as the tool rotational speed, tool plunge depth and dwell time, were determined according to the Taguchi orthogonal table L9 using a randomised approach. The optimum welding parameters for the peak tensile shear load of the joints were predicted, and the individual importance of each parameter on the tensile shear load of the friction stir spot weld was evaluated by examining the signal-to-noise ratio and analysis of variance (ANOVA) results. The optimum levels of the plunge depth, dwell time and tool rotational speed were found to be 4.8 mm, 2 s and 1500 rpm, respectively. The ANOVA results indicated that the tool plunge depth has the higher statistical effect with 69.26% on the tensile shear load, followed by the dwell time and rotational speed. The tensile shear load of the friction stir spot welding (FSSW) joints increased with increasing plunge depth. Additionally, examination of the weld cross-sections, microhardness tests and fracture characterisation of the selected friction spot welded joints were conducted to understand the better performance of the joints. All the fractures of the joints during tensile testing occurred at stir zone (SZ), where the bonded section was minimum. The tensile shear load and tensile deformation of the FSSW joints increased linearly with increasing the bonded size. The finer grain size in the SZ led to the higher hardness, which resulted in higher fracture strength. When the tensile shear load of the joints increased approximately 3-fold, the failure energy absorption of the joints increased approximately 15-fold.Item The optimization of process parameters and microstructural characterization of fiber laser welded dissimilar HSLA and MART steel joints(MDPI, 2016-10-10) Yüce, Celalettin; Tutar, Mümin; Karpat, Fatih; Yavuz, Nurettin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-8474-7328; 0000-0003-1387-907X; 0000-0002-7286-3433; A-5259-2018; R-3733-2017; J-2753-2016; 56237466100; 54406234300; 24366799400; 6701698986Nowadays, environmental impact, safety and fuel efficiency are fundamental issues for the automotive industry. These objectives are met by using a combination of different types of steels in the auto bodies. Therefore, it is important to have an understanding of how dissimilar materials behave when they are welded. This paper presents the process parameters' optimization procedure of fiber laser welded dissimilar high strength low alloy (HSLA) and martensitic steel (MART) steel using a Taguchi approach. The influence of laser power, welding speed and focal position on the mechanical and microstructural properties of the joints was determined. The optimum parameters for the maximum tensile load-minimum heat input were predicted, and the individual significance of parameters on the response was evaluated by ANOVA results. The optimum levels of the process parameters were defined. Furthermore, microstructural examination and microhardness measurements of the selected welds were conducted. The samples of the dissimilar joints showed a remarkable microstructural change from nearly fully martensitic in the weld bead to the unchanged microstructure in the base metals. The heat affected zone (HAZ) region of joints was divided into five subzones. The fusion zone resulted in an important hardness increase, but the formation of a soft zone in the HAZ region.Item Optimum design of tractor clutch PTO finger by using topology and shape optimization(American Society of Mechanical Engineers, 2016) Genç, Mehmet Onur; Doğan, Oğuz; Karpat, Fatih; Kaya, Necmettin; Yüce, Celalettin; Yavuz, Nurettin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0003-4203-8237; 0000-0001-8474-7328; 0000-0002-8297-0777; 0000-0003-1387-907X; AAV-7897-2020; A-5259-2018; R-4929-2018; R-3733-2017; GKI-9429-2022; GXH-1702-2022; 7006415878; 24366799400; 7005013334; 56237466100; 6701698986Tractors are one of the most important agricultural machinery in the world. They provide agricultural activities in challenging conditions by using various agricultural machineries which are added on them. Therefore, there has been a rising demand for tractor use for agricultural activities. During the power transmission, tractor clutches are exposed to high static and cyclic loading directly. Thus, most of clutch parts fail before completing their design life which is under 106 cycles. Especially, because of the high stress, there are a number of fractures and breakages are observed around the pin area of the finger mechanisms. Due to these reasons, it is necessary to redesign these fingers by using modern optimization techniques and finite element analysis. This paper presents an approach for analysis and re-designs process of tractor clutch PTO finger. Firstly, the original designs of the PTO fingers are analyzed by using finite element analysis. Static structural analyses are applied on these fingers by using ANSYS static structural module. The boundary conditions are determined according to the data from the axial fatigue test bench. Afterwards, the stress-life based fatigue analyses are performed with respect to Goodman criterion. It is seem that the original design of the PTO finger, failed before the design life. Hence, the PTO finger is completely redesigned by using topology and shape optimization methods. Topology optimization is used to find the optimum material distribution of the PTO fingers. Topology optimization is performed in solidThinking Inspire software. The precise dimensions of the PTO fingers are determined by using shape optimization and response surface methodology. Two different design parameters, which are finger thickness and height, are selected for design of experiment and 15 various cases are analyzed. By using DOE method three different equations are obtained which are maximum stresses, mass, and displacement depending on the selected design parameters. These equations are used in the optimization as objective and constraint equations in MATLAB. The results indicate that the proposed models predict the responses adequately within the limits of the parameters being used. The final dimensions of the fingers are determined after shape optimization. The new designs of the PTO fingers are re-Analyzed in terms of static and fatigue analysis. The new design of the PTO finger passed the analysis successfully. As a result of the study, the finger mass is increased 7% but it is quite small. Maximum Equivalent Von-Misses stress reduction of 25.3% is achieved. Fatigue durability of the PTO finger is improved 53.2%. The rigidity is improved up to 27.9% compared to the initial design. The optimal results show that the developed method can be used to design a durable, low manufacturing cost and lightweight clutch parts.