Person: TÜFEKCİ, KENAN
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TÜFEKCİ
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KENAN
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Publication Stress relaxation of 3d printed pla of various infill orientations under tensile and bending loadings(Wiley, 2023-07-18) TÜFEKCİ, KENAN; Çakan, Betül Gülçimen; GÜLÇİMEN ÇAKAN, BETÜL; Küçükakarsu, Volkan Mesut; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0001-5358-1396; AAG-7076-2021In recent years, the widespread use of 3D printing technology in various industries has highlighted the crucial issue of how 3D printed polymers behave mechanically when subjected to stress relaxation. The time-independent mechanical properties of these polymers, as well as their stress relaxation behavior, are both affected by the 3D printing parameters used. Therefore, this study examines the stress-relaxation behavior of PLA under tensile and bending loading modes, specifically investigating how different raster orientations affect this behavior. The findings indicate that the +/- 45 degrees infill orientation had the least amount of relaxation in both tensile and bending modes compared to the other orientations. Additionally, there was higher stress relaxation in the bending loading mode across all infill orientations. The findings indicate that the experimental duration should exceed 750 s to achieve an accurate model, as both Maxwell-Weichert elements contribute to stress relaxation during this period. On the other hand, extending the test beyond 20,000 s is not necessary since neither of the elements contributes significantly to stress relaxation.Publication A variable clutch mechanism for adjustable stiffness actuators based on bending and torsion of prismatic beams(MDPI, 2023-01-01) Reis, Murat; Tüfekçi, Kenan; REİS, MURAT; TÜFEKCİ, KENAN; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0001-5853-488X; 0000-0001-5358-1396; AAI-1786-2019; AAG-7076-2021Today, a major obstacle to developing locomotion mechanisms that are as safe and energy efficient as living organisms has been overcome with the development of actuators with adjustable stiffness. This work presents an innovative clutch mechanism whose stiffness can be adjusted based on the combined bending and torsion of the prismatic beams. In this way, the stiffness of any rotary actuator can be adjusted with the help of this clutch mechanism. The adjustable clutch mechanism consists of elastic prismatic beams placed in any position in the power transmission unit. The stiffness of the clutch mechanism is controlled by varying the active clutch length of these prismatic elastic beams using an additional actuator. This work is a new version developed to solve the mechanical problems observed in our previous studies using elastic cylindrical beams. Cylindrical beams subjected to dynamic bending have a higher risk of cracking on the cylindrical surface over time. The cross-section of cylindrical beams subjected to bending is very narrow at the point furthest from the center, which bears the greatest load in bending. For this reason, it has been observed that the beams break due to micro-cracks on the surfaces of the cylindrical beams in long-term use. However, the rectangular beam proposed as a solution to this mechanical problem is subject to combined torsion and bending, complicating the analytical solution. In this study, the stiffness variation of an adjustable elastic coupling mechanism depending on the coupling length was obtained with a simplified discrete analytical approach. Torsional and bending stiffness of the prismatic beams were calculated separately, and their sum gave the angular stiffness of the actuator. The analytical results obtained using this simple approach are compared with the experimental and finite element analysis results. The results show that the current design can adjust the stiffness over a wide range and the simple analytical approach gives more accurate results as the clutch length increases.Publication Effect of sample dimension on three and four points bending tests of fine crystalline marble and its relationship with direct tensile strength(Iop Publishing Ltd, 2019-01-01) Efe, Tamer; Şengün, Nazmi; Demirdağ, Servet; Altındağ, Rasit; Tüfekçi, Kenan; TÜFEKCİ, KENAN; Mühendislik Fakültesi; Makine Mühendisliği Ana Bilim Dalı; AAG-7076-2021The indirect tensile strength test methods such as three and four points bending tests and Brazilian tests have been commonly used tensile strength determination and other mechanical properties of rocks since it is a quick, easy, and inexpensive testing methods. EN and ASTM standards suggested that sample dimensions of three and four points bending tests have been different from each other. The aim of this study, in order to analyses the effect of sample dimension on bending strength property of fine crystalline marble and is to determine the direct tensile strength (DTS) of rock by using new dumbbell shape. Indirect tensile strength of marble was determined by using three and four-point bending test methods according to related standards. In addition to experimental study, stress distribution and stress intensity on the sample was analyzed by using ANSYS. As a result, four-point bending test is more suitable for determining of tensile strength of marble.Publication The relationship between spirulina platensis and selected biomechanical indicators of tibiae in rats(Czech Academy Agricultural Sciences, 2020-01-01) Süzer, Bayram; Seyidoğlu, Nilay; Tüfekçi, Kenan; İnan, Sevda; SÜZER, BAYRAM; TÜFEKCİ, KENAN; Veteriner Fakültesi; Anatomi Ana Bilim Dalı; 0000-0002-2687-1221; 0000-0001-5358-1396; AAG-7076-2021; GLV-3407-2022There are several dietary supplements, particularly herbal foods, that have been used in an attempt to improve bone growth. In this study, we aim at determining the effects of low- and high-doses of Spirulina platensis, a "Superfood", on the bone growth and biomechanical indicators. Thirty Wistar rats, weighing 250 g, at the age of 7-8 weeks were assigned to three groups: The Control group (basal diet), Low-dose group (LDG; 500 mg/kg) and High-dose group (HDG; 1 000 mg/kg) of S. platensis. S. platensis was given daily by oral gavage in a 45-day-trial. At the end of the study, the right tibiae were collected and subjected to bone biomechanical tests (bone weight, bone length, maximum load, stiffness, breaking deflection, fracture toughness, post-yield displacement and yield load). Serum samples were also analysed for the calcium and phosphorus concentrations. There were significant increases in bone weight, bone length, maximum load, breaking deflection, work to fracture, post-yield displacement and yield load (P = 0.025, P = 0.019, P = 0.030, P = 0.015, P = 0.031, P = 0.028, P = 0.049, respectively), whereas stiffness non-significantly increased. However, there were no significant differences (P > 0.05) for any variables between the LDG and the HDG. Although the serum phosphorus concentrations showed no differences among any of the groups, the serum calcium concentration increased significantly in LDG compared to Control group (P = 0.009; 7.14 +/- 0.47 and 9.45 +/- 0.67, respectively). However, no differences were observed in HDG in terms of serum calcium. In conclusion, S. platensis had positive effects on the bone growth and biomechanical bone features. Therefore, our study supports the use of S. platensis as an alternative food additive for bone growth and health in growing animals.Publication Comparison of some biomechanical properties of tibiotarsus in four different feather color lines of 60-day old female quails(Facta-fundacio Arnco Ciencia Tecnologia Avicolas, 2020-01-01) Süzer, Bayram; SÜZER, BAYRAM; Petek, Metin; PETEK, METİN; Tüfekçi, Kenan; TÜFEKCİ, KENAN; Arıcan, İlker; ARICAN, İLKER; Abdourhamane, Ibrahima Mahamane; Yıldız, Hüsnü; Mühendislik Fakültesi; Anatomi Ana Bilim Dalı; 0000-0002-2687-1221; 0000-0001-5358-1396; 0000-0001-6342-0094; 0000-0001-8789-3101; 0000-0003-2091-0303; GLV-3407-2022; AAG-7076-2021This study aimed to compare some morphological and mechanical measurements of four different color female quails to contribute to the formation of the morphological database.Quails are the smallest farmed avian species which are becoming more important for the poultry industry. They are also used as experimental animals and are valuable birds for researches. Genetic factors are important determinants of bone strength. Thus, skeletal disorders may be reduced by breeding selection in quails. Forty female quails with four different feather colors, including wild, white, yellow, and black, were compared at 60 days of age. Each quail group contained ten individuals. A three-point bending test was performed with a custom-made testing machine designed for low strength materials. No significant difference was found between the groups in terms of body weight. The tibiotarsus weight in wild and black (0,665 +/- 0,055g and 0,687 +/- 0,025g, respectively) was significantly lower than in the others but, the significant highest value was in white quails (0,758 +/- 0,063g) (p=0.001). Significantly shorter tibiotarsus was observed in the black quails (51,286 +/- 1,374mm), while the tibiotarsi of the white and yellow quails were the tallest (53,216 +/- 1,796mm and 53,083 +/- 1,092mm, respectively) (p=0.005). There were no significant differences among the groups in the biomechanical properties of tibiotarsus, except stiffness. Stiffness was the highest in the white quails (109,500 +/- 3,807 N/mm) and the lowest in the black quails (99,000 +/- 9,498 N/mm) (p=0.042). In conclusion, white quails have been observed to have relatively better bone biomechanical properties compared to the other color groups at 60 days of age.Publication Effects of genotype and housing system on some bone biomechanical characteristics in broiler chickens(Ankara Üniversitesi, 2019-04-21) Süzer, Bayram; Tüfekci, Kenan; Arıcan, İlker; Petek, Metin; Abdourhamane, Ibrahima Mahamane; Özbek, Melahat; Yıldız, Hüseyin; SÜZER, BAYRAM; TÜFEKCİ, KENAN; ARICAN, İLKER; PETEK, METİN; Abdourhamane, Ibrahima Mahamane; Özbek, Melahat; YILDIZ, HÜSEYİN; Veteriner Fakültesi; Makina Mühendisliği Bölümü; 0000-0002-2687-1221; 0000-0001-5358-1396; 0000-0001-6342-0094; 0000-0001-8789-3101; AAG-7076-2021; AAA-1366-2021; X-2000-2019; AAG-7518-2021; DNZ-6767-2022; EKQ-7243-2022; FNV-0028-2022The aim of this study was to determine the effects of two genotypes (slow-growing and fast-growing) and three housing systems (deep litter, plastic slat and free-range) on some bone biomechanical properties of broiler chickens and to evaluate the interaction between genotype and housing systems. Broilers from two genotypes were reared at three different housing conditions. Fifteen bones were randomly selected from each housing system in both slow-growing and fast-growing groups, and the experiment was performed on 90 bones in total. To determine bone characteristic and biomechanical traits of tibiotarsi, bones collected from right leg and then weighed, cortical area measurements and three-point bending tests were applied. Both live body weight and carcass weight were significantly affected by genotype and housing systems. There was no interaction between genotype and housing system in terms of bone weight, cortical area, breaking strength, bending strength, and deflection. Also, housing systems had no statistical effect on these parameters. Fast-growing broilers were significantly had heavier tibiotarsi, larger cortical area and higher breaking strength than slow-growing broilers, while bending strength was significantly lower in fast-growing broilers. Deflection was not affected by genotype or by housing system. In conclusion, bone geometry and biomechanical properties were not affected by housing systems but by genotype. Fast-growing broilers had better bone morphology and stronger bones than slow-growing genotype. Therefore, fast-growing genotype can provide positive effects on bone growth and mechanical properties in broilers.