Person: KARPAT, FATİH
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KARPAT
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FATİH
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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 The effect of micro grooving on goat total knee replacement: A finite element study(Amer Soc Mechanical Engineers, 2020-01-01) Khandaker, Morshed; Haleem, Amgad; Williams, Wendy; Boyce, Kari E.; Clary, Erik; Agrawal, Kshitijkumar; Kalay, Onur Can; Karpat, Fatih; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-5985-7402; 0000-0001-8643-6910; 0000-0001-8474-7328; A-5259-2018A method to improve the mechanical fixation of a total knee replacement (TKR) implant is clinically important and is the purpose of this study. More than one million joint replacement procedures are performed in people each year in the United States, and experts predict the number to increase six-fold by the year 2030. Whether cemented or uncemented, joint prostheses may destabilize over time and necessitate revision. Approximately 40,000 hip arthroplasty surgeries have to be revised each year and the rate is expected to increase by approximately 140% (and by 600% for total knee replacement) over the next 25 years. In veterinary surgery, joint replacement has a long history and the phenomenon of surgical revision is also well recognized. For the betterment of both people and animals, improving the longevity of arthroplasty devices is of the utmost clinical importance, and towards that end, several strategies are under investigation. One approach that we explore in the present research is to improve the biomechanical performance of cemented implant systems by altering the implant surface architecture in a way that facilitates its cement bonding capacity. Beginning with the Charnley system, early femoral stems were polished smooth, but a number of subsequent designs have featured a roughened surface-created with bead or grit blasting-to improve cement bonding. Failure at the implant-cement interface remains an issue with these newer designs, leading us to explore in this present research an alternate, novel approach to surface alteration- specifically, laser microgrooving. This study used various microgrooves architectures that is feasible using a laser micromachining process on a tibia tray (TT) for the goat TKR. Developing the laser microgrooving (LM) procedure, we hypothesized feasibility in producing parallel microgrooves of precise dimensions and spacing on both flat and round metallic surfaces. We further hypothesized that laser microgrooving would increase surface area and roughness of the cement interface of test metallic implants and that such would translate into an improved acute mechanical performance as assessed in vitro under both static and cyclic loads. The objective was to develop a computational model to determine the effect of LIM on the tibial tray to the mechanical stimuli distributions from implant to bone using the finite element method. This study designed goat TT 3D solid model from a computer topography (CT) images, out of which three different laser microgrooves were engraved on TT sample by varying depth, height and space between two adjacent grooves. The simulation test results concluded that microgrooves acchitecures positively influence microstrain behavior around the implant/bone interfaces. There is a higher amount of strain observed for microgroove implant/bone samples compared to non-groove implant/bone samples. Thus, the laser-induced microgrooves have the potential to be used clinically in TKR components.Publication Investigation of infectious droplet dispersion in a hospital examination room cooled by split-type air conditioner(Springer, 2024-05-08) Yüce, Bahadir Erman; Kalay, Onur Can; Karpat, Fatih; Alemdar, Adem; Temel, Şehime Gülsün; Dilektaşlı, Aslı Görek; Başkan, Emel Bülbül; Özakın, Cüneyt; Coşkun, Burhan; YÜCE, BAHADIR ERMAN; Kalay, Onur Can; KARPAT, FATİH; ALEMDAR, ADEM; TEMEL, ŞEHİME GÜLSÜN; GÖREK DİLEKTAŞLI, ASLI; BÜLBÜL BAŞKAN, EMEL; ÖZAKIN, CÜNEYT; COŞKUN, BURHAN; Bursa Uludağ Üniversitesi/Yenişehir İbrahim Orhan Meslek Yüksekokulu/İklimlendirme ve Soğutma Teknolojisi Bölümü.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/Sağlık Bilimleri Enstitüsü.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Tıbbi Genetik Anabilim Dalı.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Histoloji ve Embriyoloji Anabilim Dalı.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Göğüs Hastalıkları Anabilim Dalı.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Dermatoloji Anabilim Dalı.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Enfeksiyon Hastalıkları ve Mikrobiyoloji Anabilim Dalı.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Üroloji Anabilim Dalı.The novel coronavirus (SARS-CoV-2) outbreak has spread worldwide, and the World Health Organization (WHO) declared a global pandemic in March 2020. The transmission mechanism of SARS-CoV-2 in indoor environments has begun to be investigated in all aspects. In this regard, many numerical studies on social distancing and the protection of surgical masks against infection risk have neglected the evaporation of the particles. Meanwhile, a 1.83 m (6 feet) social distancing rule has been recommended to reduce the infection risk. However, it should be noted that most of the studies were conducted in static air conditions. Air movement in indoor environments is chaotic, and it is not easy to track all droplets in a ventilated room experimentally. Computational Fluid Dynamics (CFD) enables the tracking of all particles in a ventilated environment. This study numerically investigated the airborne transmission of infectious droplets in a hospital examination room cooled by a split-type air conditioner with the CFD method. Different inlet velocities (1, 2, 3 m/s) were considered and investigated separately. Besides, the hospital examination room is a model of one of the Bursa Uludag University Hospital examination rooms. The patient, doctor, and some furniture are modeled in the room. Particle diameters considered ranged from 2 to 2000 mu m. The evaporation of the droplets is not neglected, and the predictions of particle tracks are shown. As a result, locations with a high infection risk were identified, and the findings that could guide the design/redesign of the hospital examination rooms were evaluated.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 The effect of hamatum curvature angle on carpal tunnel volumetry: A mathematical simulation model(Hindawi Ltd, 2020-03-10) Akdağ, Gökhan; Alp, Nazmi Bülent; Kaleli, Tufan; KALELİ, HÜSEYİN TUFAN; Kalay, Onur Can; Karpat, Fatih; KARPAT, FATİH; Macunluoğlu, Aslı Ceren; Oral, Gamze Saygı; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Ortopedi Anabilim Dalı.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Biyoistatistik Anabilim Dalı.; 0000-0003-3656-0088; 0000-0003-1109-8958; 0000-0001-8643-6910; 0000-0001-8474-7328; 0000-0002-6802-5998; AAB-6136-2022; A-5259-2018In carpal tunnel volume measurements, the angle of the hamatum curvature is not considered a variable, and its effect on carpal tunnel volume has not been investigated. We hypothesize that a change in the anatomical angle of the hamatum curvature changes the carpal tunnel volume. To prove our hypothesis, we used a mathematical simulation model considering the carpal tunnel as a truncated cone. We reviewed the wrist CT scans of 91 adults (>18 years of age), including 51 men and 40 women. We measured the angle of the hamatum curvature in the CT scans. We measured cross-sectional areas at the outlet of the carpal tunnel at the level of the trapezium and hook of hamate (r1) and at the inlet at the level of the scaphoid and pisiform (r2) and the length (h) of the carpal tunnel. We attempted to calculate the effect of 2 degree by 2-degree changes in the angle of the hamatum curvature between the angles of 98 degrees and 140 degrees on the carpal tunnel volume. The mean angle of the hook of hamatum of the subjects was 122.55 degrees +/- 8.20 degrees (range, 97.20 degrees-139.31 degrees). No suitable cutoff point was found for the angle values. There was no difference between the gender groups according to the angle value. The data clearly show that there is a high correlation between carpal tunnel volume and the angle of hamatum curvature. The results of our study emphasize the importance of taking into account the anatomical features of the hamatum bone, especially the angle of curvature, which may play a predisposing role in idiopathic carpal tunnel syndrome.Publication Vibration-based early crack diagnosis with machine learning for spur gears(Amer Soc Mechanical Engineers, 2020-01-01) Karpat, Fatih; KARPAT, FATİH; Dirik, Ahmet Emir; DOĞAN, OĞUZ; DİRİK, AHMET EMİR; Kalay, Onur Can; Korcuklu, Burak; KORCUKLU, BURAK; Doğan, Oğuz; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Otomotiv Mühendisliği Bölümü.; 0000-0001-8474-7328; 0000-0001-8643-6910; KIK-4851-2024; A-5259-2018Gear mechanisms are one of the most significant components of the power transmission systems. Due to increasing emphasis on the high-speed, longer working life, high torques, etc. cracks may be observed on the gear surface. Recently, Machine Learning (ML) algorithms have started to be used frequently in fault diagnosis with developing technology. The aim of this study is to determine the gear root crack and its degree with vibration-based diagnostics approach using ML algorithms.To perform early crack detection, the single tooth stiffness and the mesh stiffness calculated via ANSYS for both healthy and faulty (25-50-75-100%) teeth. The calculated data transferred to the 6-DOF dynamic model of a one-stage gearbox, and vibration responses was collected. The data gathered for healthy and faulty cases were evaluated for the feature extraction with five statistical indicators. Besides, white Gaussian noise was added to the data obtained from the 6-DOF model, and it was aimed at early fault diagnosis and condition monitoring with ML algorithms.In this study, the gear root crack and its degree analyzed for both healthy and four different crack sizes (25%-50%-75%-100%) for the gear crack detection. Thereby, a method was presented for early fault diagnosis without the need for a big experimental dataset. The proposed vibration-based approach can eliminate the high test rig construction costs and can potentially be used for the evaluation of different working conditions and gear design parameters. Therefore, catastrophic failures can be prevented, and maintenance costs can be optimized by early crack detection.Publication Design and analysis of lattice structure applied humerus semi-prosthesis(Walter De Gruyter Gmbh, 2023-06-05) Savran, Efe; Kalay, Onur Can; Alp, Nazmi Bülent; Karpat, Fatih; Savran, Efe; Kalay, Onur Can; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makina Mühendisliği Bölümü.; 0000-0001-8474-7328; IUG-4938-2023; GDQ-4936-2022; A-5259-2018Bone tissue loss may occur in bone structures, which are one of the elements that provide the body's endurance and movement of living things, due to situations such as falling, hitting, or cancer formation. In bad scenarios, applications such as an external plate or internal rod addition are made to regain the old durability of the structure. At the same time, full or semi-prosthesis applications can be made in cases where the original bone structure cannot be preserved. With today's advanced possibilities, lattice structures can be produced effortlessly with the additive manufacturing (AM) method. Here, the formation of the structure that can show anisotropic behavior depending on the production and the effect of the roughness caused by the production quality should also be seen in the process plan. In this study, it was aimed to compare the durability of titanium (Ti-6Al-4V) and magnesium (ZK60) materials for humeral half prosthesis using cubic-based lattice structure and to show their differences compared to the original bone structure. Maximum stress and deformation values were obtained by performing analyses with the finite element method on the lattice semi-humerus prosthesis obtained with this aim. Reliability analysis was made on the data obtained, and parameter optimization of the lattice structure was aimed. As a result of the study, it was seen that the lattice structure with 65% porosity compared to the reference values is reliable and with the same reliability rate, magnesium provides approximately 60% lightness compared to titanium.Publication A comparative 3d finite element computational study of stress distribution and stress transfer in small-diameter conical dental implants(Univ Osijek, Tech Fac, 2021-12-01) Doğan, Oğuz; Dhanasekaran, Lokesh; Khandaker, Morshed; Kalay, Onur Can; Karaman, Hasan; Karpat, Fatih; KARPAT, FATİH; Doğan, Oguz; DOĞAN, OĞUZ; Yuce, Celalettin; YÜCE, CELALETTİN; Karpat, Esin; KARPAT, ESİN; Dhanasekaran, Lokesh; Khandaker, Morshed; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Elektrik Elektronik Mühendisliği.; 0000-0001-8643-6910; 0000-0001-8474-7328; 0000-0003-1387-907X; 0000-0001-5985-7402; A-5259-2018; GXH-1702-2022; AAV-7897-2020; R-3733-2017The implant design is one of the main factors in implant stability because it affects the contact area between the bone and the implant surface and the stressstrain distribution at the bone-implant interface. In this study, the effect of different groove geometries on stress-strain distributions in small-diameter conical implants is investigated using the finite element method (FEM). Four different thread models (rectangular, buttressed, reverse buttressed, and symmetrical profile) are created by changing the groove geometry on the one-piece implants, and the obtained results are compared. The stress shielding effect is investigated through the dimensionless numbers that characterize the load-sharing between the bone-implant. It is determined that the lowest stress distribution is observed with rectangular profiled groove geometry. Besides, it is obtained that the buttressed groove geometry minimizes the stress effects transmitted to the periphery of the implant. The symmetrical profiles had better performance than rectangular profiles in stress transfer.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; Uludağ Üniversitesi/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 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.