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Öğe Derin Kriyojenik İşlemin Farklı Bekletme Sürelerinin AISI 4140 (42CrMo4) Çeliğin Mekanik Özelliklerine Etkisi(2018) Kam, Menderes; Saruhan, HamitBu çalışmada, özellikle otomotiv endüstrisinde yaygın olarak kullanılan AISI 4140 (42CrMo4) çeliğinin mekanik özellikleri üzerinde farklı bekletme süreli derin kriyojenik işlemin etkisi incelenmiştir. Bu amaçla hazırlanan AISI 4140 çeliğinden imal edilen numunelere geleneksel ısıl işlem uygulanmış ve geleneksel ısıl işlemi tamamlayıcı bir işlem olan derin kriyojenik işlem farklı bekletme sürelerinde (12, 24, 36 ve 48 saat) - 140 C sıcaklıkta uygulanmıştır. Derin kriyojenik işlem sonrasında numunelere 200 C’ de temperleme işlemi uygulanmıştır. AISI 4140 çeliğin mekanik özelliklerinin belirlenebilmesi için sertlik ölçüm ve çekme testleri gerçekleştirilmiştir. Bu testlerden elde edilen bulgular analiz edilmiş ve karşılaştırılmıştır. Sonuçlar, farklı bekletme süreli derin kriyojenik işlemin ve derin kriyojenik işlem sonrası uygulanan temperleme işleminin AISI 4140 çeliğin mekanik özellikleri üzerinde önemli etkileri olduğunu göstermiştir. Derin kriyojenik işlemli numunelerde önemli sertlik artışları ve çekme dayanımlarında kayda değer iyileşmeler olmuştur. Ayrıca, mekanik özelliklere etkisi yönünden derin kriyojenik işlemin en uygun bekletme süresinin 36 saat olduğu tespit edilmiştir. Derin kriyojenik işlemli numunelerin çekme dayanımlarında yaklaşık % 10 ve sertlik değerlerinde ise yaklaşık % 5 iyileşme olduğu görülmüştür.Öğe Design optimization of rotor-bearing system considering critical speed using Taguchi method(Sage Publications Ltd, 2017) Yücel, Emre; Saruhan, HamitThe purpose of this study is to utilize Taguchi method, which can prove to be a handy and effective tool for determining minimum vibration response of rotor-bearing system set to avoid running at critical speed. In the study, three test cases considering different coupling type (elastic, jaw, and solid) and disc location (disc location A, B, and C) were conducted to observe behavioral changes of the shaft system considering vibration signatures. Each test case was conducted for three different shaft running speeds of 12, 18, and 24Hz. To find the minimum peak amplitude values by experimenting different combinations of the rotor-bearing system set needs a lot of experiments for reaching solution. Moreover, the solution proves costly because of the time consumed in doing many experiments. This fact depicts the importance of an efficient optimization method to be used. Taguchi method can determine the design parameters, which have the greatest influence on the solution through a very limited number of experiments, for finding optimum set of rotor-bearing system. The method is performed using an iterative procedure to gain an optimum design.Öğe DESIGNING OPTIMUM OIL THICKNESS IN ARTIFICIAL HUMAN KNEE JOINT BY SIMULATED ANNEALING(Assoc Sci Res, 2009) Saruhan, HamitIn human knee joints, synovial fluid film covers the surface of synovium and cartilage within the joint space. Synovial joints acts as bearing in mechanical system. Although the artificial human joints differ from most mechanical bearings in their nature, they have been modeled and analyzed in terms of hydrodynamic bearing of engineering. In this study, nature inspired an algorithm, the simulated annealing (SA), is used to find minimum fluid film thickness in artificial human knee joints. It is important to optimize the film thickness of the bearing in terms of successful operation and lifetime of the implant in terms of friction and wear. The problem is complex and a time consuming process due to design variables and constraints imposed on the objective function. It is demonstrated that the SA performed and obtained convergence reliability on the optimum point.Öğe Differential evolution and simulated annealing algorithms for mechanical systems design(Elsevier B.V., 2014) Saruhan, HamitIn this study, nature inspired algorithms – the Differential Evolution (DE) and the Simulated Annealing (SA) – are utilized to seek a global optimum solution for ball bearings link system assembly weight with constraints and mixed design variables. The Genetic Algorithm (GA) and the Evolution Strategy (ES) will be a reference for the examination and validation of the DE and the SA. The main purpose is to minimize the weight of an assembly system composed of a shaft and two ball bearings. Ball bearings link system is used extensively in many machinery applications. Among mechanical systems, designers pay great attention to the ball bearings link system because of its significant industrial importance. The problem is complex and a time consuming process due to mixed design variables and inequality constraints imposed on the objective function. The results showed that the DE and the SA performed and obtained convergence reliability on the global optimum solution. So the contribution of the DE and the SA application to the mechanical system design can be very useful in many real-world mechanical system design problems. Beside, the comparison confirms the effectiveness and the superiority of the DE over the others algorithms – the SA, the GA, and the ES – in terms of solution quality. The ball bearings link system assembly weight of 634,099 gr was obtained using the DE while 671,616 gr, 728213.8 gr, and 729445.5 gr were obtained using the SA, the ES, and the GA respectively. © 2014 Karabuk UniversityÖğe Dynamic Behavior Analysis of Rotor Supported by Damped Rolling Element Bearing Housing(Gazi Univ, 2017) Saruhan, Hamit; Kam, Menderes; Kara, FuatA typical rotating machinery system consists various components, such as rotor, support bearing, and disks. These components pass out energy into the system when coincident to critical speeds. Ignoring such event might lead to disastrous breakdown of the system. Due to necessity and vital contribution to most rotating machineries, the requirements on rolling element bearings have become stricter every day. In this experimental study, the dynamic behavior and displacement of rotor supported by damped rolling element bearing housing for different running speeds and load levels are analyzed and compared.Öğe Effect of Eco-Friendly Minimum Quantity Lubrication in Hard Machining of Vanadis 10: A High Strength Steel(Wiley-V C H Verlag Gmbh, 2022) Altan Özbek, Nursel; Özbek, Onur; Kara, Fuat; Saruhan, HamitVanadis 10 SuperClean is a high vanadium alloyed powder metallurgy tool steel offering a unique combination of an excellent abrasive wear resistance in combination with a good chipping resistance. In this study, the effects of the eco-friendly (100% biodegradable plant-based) Minimum Quantity Lubrication (MQL) system on the cutting temperature, cutting tool vibration amplitude, tool wear, average surface roughness, and tool life in the turning of Vanadis 10 steel (50 HRC) used in the automotive industry are investigated. In the experiments, TiCN/Al2O3/TiN-coated cemented carbide tools are used. Experimental results showed that, compared to Dry machining, MQL produced remarkable improvements in terms of cutting temperature, cutting tool vibration amplitude, tool wear, and surface roughness. In addition, the Taguchi experimental design, ANOVA, and linear and quadratic regression analyses are applied to the experimental data. The statistical analysis found the most effective parameter on average surface roughness to be the cutting environment (86.31%). It is determined that the cutting speed was the most effective on vibration amplitude and tool wear (46.22% and 32.41%). The correlation coefficients for the linear and quadratic regression analysis were 0.9 and 0.95, respectively.Öğe The effect of full annular rub on the rotating machinery system considering different rub materials and shaft running speeds(2013) Saruhan, Hamit; Sarıdemir, Suat; Erkan, ÖmerIn this study, the effect of full annular rub on the rotating machinery system considering different rub materials and shaft running speeds was experimentally studied. Experiments were carried out for the rub materials - copper, bronze, brass, soft plastic, hard plastic, steel 304, steel 316, and steel 2379. The force and vibration signatures of shaft rub on bearing housing were analyzed. The results showed that the vibration amplitude of inboard bearing housing close to the motor increased significantly with the shaft speed increased. The spectrum for the soft plastic rub material found to has a unique characteristic so that the vibration level was lower than the baseline (without rub material) vibration.Öğe Effect of vibration and cutting zone temperature on surface topography during hybrid cooling/lubrication assisted machining of Vanadis 10(Walter De Gruyter Gmbh, 2023) Ozbek, Onur; Ozbek, Nursel Altan; Kara, Fuat; Saruhan, HamitNew alloy materials developed to meet the increasing technological needs of people come into our lives with some difficulties in terms of machinability. New cooling and lubrication techniques have been developed to facilitate the workability of such difficult-to-process materials and protect the world ecologically and the quality of the produced product. The workpiece used in this study, Vanadis 10 SuperClean, is a high vanadium alloyed powder metallurgy tool steel offering a unique combination of excellent abrasive wear resistance in combination with a good chipping resistance. The present study investigated the effects of dry, cryo, and CryoMQL cutting conditions on cutting tool vibration amplitude, cutting temperature, surface roughness, tool wear, and tool life in turning of Vanadis 10 tool steel used in the automotive industry. The experiments were performed using TiCN/Al2O3/TiN coated cemented carbide tools and cutting parameters as the constant depth of cut (1 mm), feed rates (0.08, 0.1, 0.12 mm rev(-1)), and cutting speeds (80, 100, 120 m min(-1)). The results obtained from experiments showed that spraying liquid nitrogen into the cutting zone provided significant improvements on cutting temperature, tool wear, cutting tool vibration amplitude, and surface roughness. The best results in terms of all output were achieved in the CryoMQL cutting environment. CryoMQL environment has reduced surface roughness up to 65.03 %, flank wear 56.99 %, cutting temperature 32.77 %, and cutting tool vibration amplitude up to 42.76 % compared to dry machining.Öğe The effect of vibration and cutting zonetemperature on surface roughness and tool wear ineco-friendly MQL turning of AISI D2(Elsevier Editora Ltda, 2020) Özbek, Onur; Saruhan, HamitToday, developments in technology have gained momentum more than ever, and the need for efficiency in production as well as in the ecological domain has increased significantly. Studies examining dry machining and coolant removal have been superseded by those presenting new cooling and lubrication techniques. The effects on surface roughness directly related to final product quality are being investigated in terms of tool life and employee health. This has resulted in more frequent use of the eco-friendly minimum quantity lubrication (MQL) technique, which has now become a major competitor to dry and coolant machining. In this study, AISI D2 cold work tool steel, a material widely used in the mold industry, was used as the workpiece. Tests were carried out under dry and MQL conditions and the temperature, cutting tool vibration amplitude, tool wear, surface roughness and tool life were evaluated. The experiments were carried out using two different cutting tool coating types (CVD-chemical vapor deposition and PVD-physical vapor deposition) and three different cutting speeds (60, 90 and 120 m/min) at a constant cutting depth (1 mm) and feed rate (0.09 mm/rev). Results revealed that tool wear, cutting temperature and cutting tool vibration amplitude were lower by 23, 25, and 45%, respectively, compared to dry cutting. Because of these improvements, the surface roughness of the workpiece was improved by 89% and tool life was increased by up to 267%. © 2020 The Authors.Öğe Effects of induction hardened surface depth on the dynamic behavior of rotating shaft systems(Carl Hanser Verlag, 2019) Kabasakaloğlu, Ufuk; Saruhan, HamitRotating shaft systems play many critical roles in rotating machinery. The performance of any rotating machinery is very dependent on vibrations generated by the rotating shaft. The selection of rotating shaft material is very important to meeting the enormous demand of industrial users on the capability of vibration resistance in rotating machinery. Recent requirements for using rotating shafts have heightened the need for the materials used. The heat treatment of material has received much attention over the last few decades. The research to date has tended to focus on material properties for resistance and strength rather than on dynamic behavior. The main objective of the present study is to experimentally investigate the role of induction surface hardening which is one of the most commonly used types of heat treatment on AISI 1045 steel dynamic behavior. Heat treatable AISI 1045 steel is among the most widely used in all industrial applications requiring more resistance and strength. It has received much attention over the past several decades due to its usage in rotating shafts, axles, crankshafts, and spindles. Induction surface hardening is used to sustain service life by increasing the surface hardness and vibration reliability of a material. Since induction hardened surface depth plays a very important part in the stability of the rotating shaft, three different hardened surface depths (0.5, 1.0, and 1.5 mm) are utilized. The results show that a hardened surface depth of 1.0 mm surprisingly and positively affects the dynamic behavior of the rotating shaft as compared to the hardened surface depths of 0.5 and 1.5 mm.Öğe Experimental analysis of maximum valve lift effects in cam-follower system for internal combustion engines(Korean Soc Mechanical Engineers, 2014) Sarıdemir, Suat; Saruhan, HamitDesigning valve lift of cam-follower system is very important for improving dynamic performance of internal combustion engines. Potential problems due to unwanted vibrations in high-speed engine are the follower jump, colliding surface of the valves, and seats which cause collide in a cam-follower system. The degree of collide depends on the valve lift value and valve closing velocity. Large forces and stresses are introduced when the cam and follower collide. This might cause early failure of the system due to unwanted vibration. The main purpose of present experimental study was to investigate and analyze the dynamic behavior of the cam-follower system for different valve lift values and operating speeds using time domain and frequency domain analysis technique. Two cases for maximum valve lift values of 8 and 10 mm were tested with corresponding operating speeds of 450, 930, 1440, 1950 and 2430 rpm. From the results, it was observed that the higher the operating speed, the higher amplitude values were obtained. Statistical analysis of obtained data showed that the 10 mm valve lift produced much more power than the 8 mm valve lift.Öğe Experimental Analysis of Vibration Damping Capabilities of Sleeve Bearings Printed Using FDM Method(Gazi Univ, 2022) Kam, Menderes; Saruhan, Hamit; Ipekci, AhmetIn this study, vibration damping capabilities of sleeve bearing printed from PA12 (Nylon) filament material using Fused Deposition Modeling (FDM) method was experimentally analyzed. A total of a pair of 15 sleeve bearings samples for supporting rotating shaft were printed in different filling structures (Honeycomb, 3D Honeycomb, Gyroid, Hilbert curve, Archimed cords) with different occupancy rates (10, 30 and 50 %). The experiments were performed for rotating shaft running speed of 900 rpm. Vibration amplitude values were collected with accelerometers mounted on the sleeve bearing supports. The results showed that filling structures and occupancy rates had very important role in damping capabilities of sleeve bearings.Öğe Experimental investigation of the vibration-reduction characteristics of the shaft coating for a turbocharger(Inst Za Kovinske Materiale I In Tehnologie, 2024) Ok, Murat; Saruhan, HamitA turbocharger is a system that is fitted to automotive engines to increase performance and efficiency by taking air at atmospheric pressure, compressing it to a higher pressure and passing the compressed air into the engine via the inlet valves. A turbocharger consists of a turbine and a compressor impeller interconnected with a shaft supported in most cases by journal bearings. The shaft is one of most crucial components of a turbocharger system and it operates at high speed. The shaft vibrations are an inherent phenomenon and they are travelling to the surrounding structure, effecting the stability and reliability of the turbocharger system. The selection of the appropriate shaft-material property is a critical parameter among the parameters that affect the vibration of the system. This study focuses on exploring whether it is possible to reduce the shaft vibration using different types of coating materials, including aluminum chromium nitride (AlCrN), titanium nitride (TiN) and aluminum titanium nitride (AlTiN), each having thicknesses of (2, 4, and 6) mu m, for a shaft made of AISI 4140 alloy steel. The inherent natural vibration properties, such as the resonant frequencies, damping, and mode shapes of the turbocharger shaft with and without coating, were obtained by conducting an experimental modal analysis through measurements of the frequency-response function, which is about curve fitting the data using a predefined mathematical model of the turbocharger shaft. The results were validated numerically with the finite element method. From overall results, it was observed that the AlCrN, TiN, and AlTiN coating thicknesses have a small effect on the resonant frequencies, but a good damping effect. The resonant response of the turbocharger shaft at resonant frequencies was suppressed remarkably by the AlCrN and AlTiN coatings, especially those having a thickness of 6 and 4 mu m.Öğe Experimental investigation of vibration damping capabilities of 3D printed metal/polymer composite sleeve bearings(Sage Publications Ltd, 2022) Kam, Menderes; Saruhan, Hamit; İpekçi, AhmetAdditive Manufacturing (AM) method enables to produce products easily, cheaply and quickly with more complex geometry compared to traditional production methods. In this context; Fused Deposition Modeling (FDM) is a widely used for AM method that requires a large number of process parameters. In this study, it is aimed to experimentally investigate the damping capabilities of the metal/polymer composite sleeve bearings printed using FDM. A total of 54 pieces (27 pairs) were printed from composite filaments such as nine pairs for each of PLA, PLA + 20% Bronze, and PLA + 20% Copper metal/polymer with different filling structures (Octogram spiral, Archimedian chords, and 3D Honey comb) and different occupancy rates (10, 30, and 50%), respectively. The experiments were carried out using the shaft-bearing system under the same operating conditions at a rotational speed of 900 revolution per minute (rpm), and vibration data was collected from the rotating shaft with proxy probes. Rotating shaft position is very important to determine journal position in bearing for understanding deterioration in the bearing. Bode and Orbit plots are used to detect the level of deterioration in the bearing. The value of bearing to shaft clearence can vary widely depending on application. Since the bearings were heavily loaded, they were compressed by radial load caused large clearence. The results showed that compressed bearing had significant influence on the stability of rotating shaft system and significant differences in damping capabilities of composite sleeve bearings with different filling structures and occupancy rate. Increasing occupancy rate decreases the vibration amplitude values in copper-reinforced sleeve bearing but increases in bronze-reinforced sleeve bearing. From the microstructure analysis, it has been observed that the vibration absorbation capability is better due to the more homogeneous distribution of the copper reinforced bearings than the bronze reinforced bearings. Also, vibration absorption capability of sleeve bearings with 3D Honeycomb filling structure is increased significantly proportion to the occupancy rate.Öğe Experimental research on vibration reduction characteristics of adhesively bonded beam structures with acoustic black hole geometry(Sage Publications Ltd, 2024) Ongun, Ridvan; Saruhan, HamitBeam structures are widely used in industrial applications such as automobiles, aircraft, naval architecture, trains, and buildings. The vibration characteristics of beams are inherent phenomenon and directly affect usage comfort and service life, but more dangerously may damage the structure due to excessive vibrations that are transmitted through the surrounding structure of the system. Vibration reduction of beam structures is a continuous challenge for industrial applications. It is important to reduce vibrations of the beam structures for stability. In this study, experimental research on vibration reduction characteristics of adhesively bonded beam structures with Acoustic Black Hole technique is presented. The Acoustic Black Hole, which is a geometry, tapered with a power-law profile enables vibration reduction by decreasing the velocity and the wavelength of vibration. The inherent natural vibration properties called modal parameters such as the natural frequencies, damping, and mode shapes of the beam structure with and without damping layer using power-law profile having various the Acoustic Black Hole length and exponent values were investigated and evaluated with experimental modal analysis. For validation, natural frequencies are determined numerically by the finite element method, and then compared with results obtained by the experimental modal analysis. The overall results indicated that the Acoustic Black Hole has ability to significantly suppress the vibration level and showed the capability of enhancing the damping efficiency when using the damping layer attached to the Acoustic Black Hole length of the beam structure.Öğe Experimental Spectral Analysis of Split Sleeve Bearing Clearance Effect on a Rotating Shaft System(2016) Saruhan, Hamit; Kam, MenderesBearing are one of the most widely used elements in rotating shaft systems with great risk of failure that can affect the systems. There are two broad types of bearings used in rotating shaft system: sleeve bearings or journal bearings and rolling element bearings. Split sleeve bearings are used for application where it is necessary to remove a cap for servicing or replacing bearing. Proper clearance between the shaft and the bearing is necessary to avoid vibration or loss of concentric orbit. The performance of rotating shaft system is very dependent on vibration generated by bearings. The use of vibration signal analysis is one of the most reliable measurement for this purpose. The main objective of the present study is experimentally to investigate the role of bearing clearance that is a critical parameter affecting dynamic characteristics of rotating shaft systems. The vertical bearing clearance through introduction of additional shims is operand to simulate a loose -worn- split sleeve bearing. Wear is responsible for many problems and large cost in rotating shaft system. Three different clearances configurations using shims have been tested. The results showed that a worn bearing will have a significant influence on the stability of rotating shaft system.Öğe Experimental Vibration Analysis of Cryogenic Treated Shafts Supported by Journal and Rolling Element Bearings(Gazi Univ, 2019) Kam, Menderes; Saruhan, HamitIn this study, the effects of cryogenic treatment and tempering on the vibration behaviors of rotating shafts mounted on the rolling element and journal bearings were investigated for the same loading conditions and operating speeds. In this experimental study, the data obtained with the help of proxy probes were analyzed and the results were compared. The results showed that the lowest amplitude values were obtained for the cryogenic treated shaft mounted on the journal bearing. The amplitude values of journal bearing are significantly superior to the rolling element bearings having stability in account.Öğe Experimental Vibration Analysis of Titanium Aluminum Nitride (TiAlN) Coated Milling Cutting Tool Effects on Surface Roughness of AISI 4140 Steel Products(2018) Yıldız, Mehmet; Saruhan, HamitThe vibration response of material removal process in milling has a significant effect on surface roughness of theproduct with respect to cutting tool coating. Recent requirements for improving of surface roughness haveheightened the need for milling with coated cutting tools. The main objective of this study is to experimentallyinvestigate the role of vibration behavior of cutting tool coated with titanium aluminum nitride (TiAlN) on an AISI4140 alloy steel work piece surface roughness. The vibration data from work piece were recorded for three millingcutting tools with tool diameters of 10, 12, and 16 and for each diameter different coating thicknesses of 0.0,2.0, 3.0, and 5.0 (microns) were used respectively. Vibration signals of work piece during milling process in twodirections were collected and a roughness tester was used to measure the surface roughness of work piece. Theresults showed that vibration due to cutting tool coating thickness has a significant effect on surface roughness ofwork piece. It has been observed that the maximum average surface roughness was obtained for 16 tooldiameters with coating thickness of 5.0 while the minimum average surface roughness was obtained for 10 mmtool diameters with coating thickness of 3.0 . Surface roughness can be improved by reduction sources ofvibration by using appropriate cutting tool coating thickness.Öğe FDM Yöntemi ile Üretilen Kovan Yatakların Titreşimi Sönümleme Kabiliyetlerinin Deneysel Analizi(2022) Kam, Menderes; Saruhan, Hamit; İpekçi, AhmetBu çalışmada, Ergiyik Depolayarak Modelleme (Fused Deposition Modelling - FDM) yöntemi ile üretilen kovan yatakların desteklediği milin titreşimlere karşı sönümleme kabiliyetleri deneysel olarak analiz edilmiştir. Çalışmada, PA12 (Nylon) filament malzeme kullanılarak farklı doldurma şekillerinde (Honeycomb, 3D Honeycomb, Gyroid, Hilbert curve, Archimed cords) ve doluluk oranlarında (% 10, 30 ve 50) toplam 30 adet kovan yatak üretilmiştir. Kovan yatakları analiz etmek için mil-yatak sisteminde aynı çalışma şartlarında 900 dev/dak mil dönme hızında deneysel çalışma gerçekleştirilmiş, kovan yatakların desteklerine bağlanan ivmeölçerler ile titreşim verileri toplanmıştır. Elde edilen sonuçlara göre, kovan yatakların titreşimi sönümleme kabiliyetlerinde önemli farklılıklar olduğu ve genel olarak doluluk oranları arttıkça titreşim genlik değerlerinin daha düşük olduğu görülmüştür .Öğe Improving the dynamic characteristics of a rotor system using an evolutionary algorithm(Assoc Mechanical Engineers Technicians Slovenia, 2007) Saruhan, HamitIn this paper the optimum design for improving the dynamic characteristics of a flexible, overhung rotor system is studied. The design of a flexible rotor system is a complicated process due to the large number of geometrical parameters of hydrodynamic bearings, which play an important role in the prediction of the dynamic behavior of the rotor system. There are a number of design requirements added to the rotor-system configuration that improve the dynamic characteristics within the rotor's speed range. To improve the dynamic characteristics of the rotor system, a genetic algorithm was employed and the modeling of the components of the rotor system was made with the finite-element method. Also, the method of feasible directions was used in order to validate the efficiency and applicability of the proposed method, and it proved that the proposed method in the rotor-system design is very efficient and useful for improving the dynamic characteristics of the rotor system. (c) 2007 Journal of Mechanical Engineering. All rights reserved.
