Person: KARPAT, FATİH
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KARPAT
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FATİH
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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 Fault diagnosis with deep learning for standard and asymmetric involute spur gears(Amer Soc Mechanical Engineers, 2021-01-01) Yuce, Celalettin; Dogan, Oguz; Karpat, Fatih; Dirik, Ahmet Emir; KARPAT, FATİH; DİRİK, AHMET EMİR; Kalay, Onur Can; Korcuklu, Burak; KORCUKLU, BURAK; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi; 0000-0001-8474-7328; 0000-0002-6200-1717; 0000-0001-8643-6910; 0000-0003-1387-907X; A-5259-2018; R-3733-2017Gears are critical power transmission elements used in various industries. However, varying working speeds and sudden load changes may cause root cracks, pitting, or missing tooth failures. The asymmetric tooth profile offers higher load-carrying capacity, long life, and the ability to lessen vibration than the standard (symmefric) profile spur gears. Gearbox faults that cannot be detected early may lead the entire system to stop or serious damage to the machine. In this regard, Deep Learning (DL) algorithms have started to be utilized for gear early fault diagnosis. This study aims to determine the root crack for both symmefric and asymmefric involute spur gears with a DL-based approach. To this end, single tooth stiffness of the gears was obtained with ANSYS software for healthy and cracked gears (50-100%), and then the time-varying mesh stiffness (TVMS) was calculated. A six-degrees-of-freedom dynamic model was developed by deriving the equations of motion of a single-stage spur gear mechanism. The vibration responses were collected for the healthy state, 50% and 100% crack degrees for both symmefric and asymmefric tooth profiles. Furthermore, the white Gaussian noise was added to the vibration data to complicate the early crack diagnosis task. The main contribution of this paper is that it adapts the DL-based approaches used for early fault diagnosis in standard profile involute spur gears to the asymmefric tooth concept for the first time. The proposed method can eliminate the need for large amounts of training data from costly physical experiments. Therefore, maintenance strategies can be improved by early crack detection.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 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 Effect of the cooling process on the mechanical properties and microstructural behavior of extruded az31 and am50 mg alloys(Walter De Gruyter Gmbh, 2021-07-01) Kurtulus, Enes; Sapmaz, Irem; Karpat, Faith; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0001-8474-7328; A-5259-2018During the extrusion of magnesium alloys, temperature change could have a significant effect on the outcome. When this effect is not considered, some commonly known defects might be observed, such as hot cracking. In this study, all samples consist of extruded AZ31 and AM50 magnesium alloys as a solid profile, but the methods by which they are cooled, such as air cooling and water quenching, vary. The effects of cooling methods on tensile-compression behavior and the microstructural properties of the samples were investigated. Test samples were obtained in extrusion direction and perpendicular to the extrusion direction separately for mechanical tests. The main purpose of this study was to investigate the effect of different cooling methods on the mechanical properties and microstructural behavior of AZ31 and AM50 magnesium alloys after extrusion, once different cooling methods were applied. According to the microstructural investigation results, an AM50 magnesium alloy has a finer grain structure as compared with an AZ31 alloy according to both cooling methods in the extrusion process. The average grain size values of both alloys were found to be higher for water cooling. Cooling methods have significant effects on the tensile properties of both alloys, depending on their extrusion directions.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.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 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; Bursa Uludağ Üniversitesi/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 Laser-induced microgrooves improve the mechanical responses of cemented implant systems(MDPI, 2020-04-27) Khandaker, Morshed; Moussa, Abdellah Ait; Sama, Desmond Nuyebga; Safavinia, Fereshteh; Hazra, Susmita; Kalay, Onur Can; Karpat, Fatih; Clary, Erik; Haleem, Amgad; Kalay, Onur Can; KARPAT, FATİH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-8643-6910; 0000-0001-8474-7328; GDQ-4936-2022 ; A-5259-2018The impact of a laser-induced microgroove (LIM) architecture on mechanical responses of two cemented implant systems was evaluated. One system consisted of two aluminum alloy rods bonded end-to-end by polymethylmethacrylate cement. The second system consisted of a custom-made, aluminum tibial tray (TT) cemented in an artificial canine tibia. Control specimens for each system were polished smooth at the cement interface. For LIM samples in the rod system, microgrooves were engraved (100 mu m depth, 200 mu m width, 500 mu m spacing) on the apposing surface of one of the two rods. For TT system testing, LIM engraving (100 mu m spacing) was confined to the underside and keel of the tray. Morphological analysis of processed implant surfaces revealed success in laser microgrooving procedures. For cemented rods tested under static tension, load to failure was greater for LIM samples (279.0 +/- 14.9 N vs. 126.5 +/- 4.5 N). Neither non-grooved nor grooved TT samples failed under cyclic compression testing (100,000 cycles at 1 Hz). Compared with control specimens, LIM TT constructs exhibited higher load to failure under static compression and higher strain at the bone interface under cyclic compression. Laser-induced microgrooving has the potential to improve the performance of cemented orthopedic implants.