Person: KENTLİ, AYKUT
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KENTLİ
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AYKUT
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Publication Open Access LATHE SELECTION USING ANALYTIC HIERARCHY PROCESS AND INFORMATION AXIOM(CENTRAL BOHEMIA UNIV, 2016-09-26) KENTLİ, AYKUT; Kentli, Aykut; Akbas, Serhat; Hajek, P; Sahota, T; Jones, MASelection of appropriate equipment, place, or employee is a problem that needs consideration by industry, as capacities develop and efficiencies become more valued over the recent decades. Several decision-making techniques have been developed and applied to many different areas to evaluate their reliability. This study focuses on the application of a hybrid decision-making technique of Analytic Hierarchy Process and Information Axiom to solve the problem of lathe selection. Results show that appropriate machine tools can easily be selected within a short time using this approach.Publication Metadata only Experimental observation of tool wear, cutting forces and chip morphology in face milling ofcobalt based super-alloy with physical vapour deposition coated and uncoated tool(ELSEVIER SCI LTD, 2007) KENTLİ, AYKUT; Aykut, Seref; Bagci, Eyup; Kentli, Aykut; Yazicioglu, OsmanCobalt base superalloys are used extensively in applications requiring good wear, corrosion and heat resistance. The main goal of this study is to examine the effect of machining conditions (cutting speed, feed rate and depth of cut) on tool wear, chip morphology and cutting forces in symmetric face milling of cobalt base superalloy with physical vapour deposition coated and uncoated inserts. with the aim of achieving to achieve this goal, 90 milling experiments were carried out with different cutting speeds, feed rate and depth of cut under dry cutting conditions. The settings of machining parameters were determined by using general full factorial design method. Chip morphology, cutting forces and tool wear were compared by using PVD coated and uncoated hard metal inserts which are obtained dependent on feed rate, cutting speed and cutting depth. The cutting forces increase as the feed rate and depth of the cut increases, but cutting speeds' effect on cutting forces has not been observed for symmetric face milling. (C) 2006 Elsevier Ltd. All rights reserved.Publication Metadata only Novel SPD Method: Twisted Variable Channel Angular Extrusion(KOREAN INST METALS MATERIALS) KENTLİ, AYKUT; Ozbeyaz, Kerim; Kaya, Hasan; Kentli, AykutDifferent types of SPD techniques are applicable and have been studied by various researchers. All of them have several advantages and disadvantages. Equal Channel Angular Pressing (ECAP) is one of the most popular SPD techniques and is still being developed. The aim of this paper is to improve the efficiency of ECAP process by putting forward a novel design (Twisted Variable Channel Angular Pressing (TV-CAP)) and also to achieve higher mechanical properties when compared to conventional ECAP processes. For this purpose, a new TV-CAP die was designed by combining three different methods: ECAP, Twist Extrusion, and Direct Extrusion. The new design was able to integrate the advantages of each method to the workpiece material. In this context, the design parameters of the TV-CAP die were first identified by finite element analysis (FEA) in Deform-3D. The TV-CAP die was produced according to the determined parameters and AA5083 alloy was pressed with this novel die. Hardness and tensile tests were carried out to compare mechanical properties. In addition, Optical Microscope, SEM, TEM images were taken, and XRD and EBSD analyses were carried out to examine the changes in grain structure. As a result of this experimental study, an increase of 197.3% was observed in the hardness value and an increase of 144.7% was achieved in the tensile strength value by using the novel TV-CAP die. These results also agreed with the effective strain values obtained from the FEA.Publication Metadata only Comparative assessment of support plates' influences on delamination damage in micro-drilling of CFRP laminates(ELSEVIER SCI LTD, 2017) KENTLİ, AYKUT; Dogrusadik, A.; Kentli, A.In this study, drilling induced delamination damage which occurs during micro-drilling of CFRP laminates was investigated experimentally under variable cutting speeds and feed rates. Unlike the previous studies, the delamination factors in micro-drilling of CFRP laminates were precisely calculated and compared for supported and unsupported cases. Using support plates which are placed front and rear sides of the CFRP laminate is one of the methods which limits the delamination damage. Two different setups of support plates were used in the experiments. In the first setup, the entry board was aluminum plate and the backing board was phenolic plate. In the second setup, the entry board was brass plate and the backing board was wooden plate. Hole pictures were taken from each CFRP laminate by using a digital microscope. The first, the middle and the last three holes were inspected from the front and rear sides of the CFRP laminate. Minitab was used to evaluate the experiments' outputs, and response surface method was used to optimize the process parameters. It has been revealed that the delamination damage in micro-drilling differs from the delamination damage in conventional drilling of CFRP laminates. Obviously, the process exhibits unusual delamination behavior as process size decreases. (C) 2017 Elsevier Ltd. All rights reserved.Publication Open Access A novel design on polymeric material recycling technology(2021-09-23) KENTLİ, AYKUT; Tanriver, Kursat; Dilibal, Savas; Sahin, Haydar; Kentli, AykutThe necessity for recycling of wastes has increased nowadays and there are various solutions according to the types of wastes which are presented accordingly. By observing these solutions, the recycling system from the waste collection and separation system of the long-term disappearing of polymer waste to the additive manufacturing design stage has been indicated. Waste collection and separation systems have been reviewed and systems to be used effectively in the systematic way have been exemplified. Among four different separating systems which are with rotating, rail and fixed containers, fixed container four-sorting waste separation systems were chosen and developed as a mechatronic system design. The mechatronic system design is very prominent in order to create efficient and economical mechanisms in fixed-container four-sorting waste separation collection system (FCWS) applications. In addition, physical mechatronic system design (MSD), mechanical design, material selection, electrical electronic design sub-heading and cost analysis were made. In this study, the necessity and importance of the waste separation plants are revealedPublication Open Access A new severe plastic deformation method: thin-walled open channel angular pressing (TWO-CAP)(SPRINGER LONDON LTD, 2020-01) KENTLİ, AYKUT; Sahbaz, Mehmet; Kaya, Hasan; Kentli, AykutIn this study, a novel severe plastic deformation method, named as thin-walled open channel angular pressing (TWO-CAP), was developed and applied to AZ31 magnesium alloy beams in U-type cross-sectional shape. First of all, the principles of the method with all parameters were determined, and the analytical model of the system was generated, and then the study was supported with the numerical analysis. Then, a proper experimental setup was established by considering theoretic outputs. After that, AZ31 magnesium alloy specimens were machined from bulk material in U-type shape as to fit the die channel, and then these specimens were annealed and pressed along the TWO-CAP die. Following the experimental studies, the specimens were tested in order to define the changes in mechanical and microstructural properties. In this stage, the tension test and hardness test were applied to determine the mechanical properties, while optical microscope, scanning electron microscope, energy dispersive spectrometry, X-ray diffraction, and transmission electron microscope analyses were applied to see the changes in microstructure. As a result, an improvement on strength, hardness, and toughness was observed depending on the changes on the microstructure and grain refinement due to the large plastic deformation.Publication Open Access EXPERIMENTAL AND ANALYTICAL INVESTIGATION ON EFFECT OF STATOR WINDING TYPE TO EQUIVALENT CIRCUIT PARAMETERS OF INDUCTION MOTORS(CENTRAL BOHEMIA UNIV, 2016-09-26) KENTLİ, AYKUT; Kentli, Fevzi; Kentli, Aykut; Hajek, P; Sahota, T; Jones, MABecause of development in technology, the design of electrical machinery is changing. Induction motors, mostly used as electrical equipment, have developed over the years. One analytically studied area is the stator winding. Generally, each manufacturer uses techniques that directly affect the power of motors and thus, motor efficiency. In this study, the effects of three different stator winding types on motor parameters are investigated. Experiments are performed under no-load, load, and locked rotor conditions. Terminal voltage, power per phase, and phase current values are measured. Power and certain parameters are calculated using an equivalent circuit model. Lastly, a comparison of the results is provided.Publication Metadata only Microstructure development and mechanical behaviour of pure copper processed by the novel TWO-CAP procedure(2023-01-01) KENTLİ, AYKUT; ÖĞÜT, SERKAN; KAYA H., UÇAR M., Ş Ahbaz M., KENTLİ A., Özbeyaz K., ÖĞÜT S.In this study, thin-walled open channel angular pressing (TWO-CAP) technique was applied to pure copper specimens as a novel severe plastic deformation (SPD) method. The TWO-CAP process was applied to the specimens up to four passes. After each pass, the microstructural and mechanical characterization of the material was investigated by tensile and hardness tests along with OM, SEM, EDS, TEM and XRD analyses. As a result, a highly increase in the mechanical properties was obtained, in addition satisfactory grain refinement was observed in microstructures. Strength and hardness values were positively affected from the minimizing the grain sizes after TWO-CAP process. Another reason of the improvements in mechanical properties can be explained as the increase in dislocation density. Furthermore, the effect of the TWO-CAP process on the dislocation density of the material has been demonstrated by XRD and TEM analyses in nanoscale. Moreover, the strain equation has been developed analytically and the effect of each pass on strain was calculated. Finally, the effect of the process on the stress-strain properties of the material was examined by the numerical analysis method and the study was verified.Publication Metadata only Influence of injection molding parameters on electrical resistivity of carbon nanotube reinforced polycarbonate(WALTER DE GRUYTER GMBH, 2016) KENTLİ, AYKUT; Donmez, Sinan; Kentli, AykutElectrical properties of plastic products can be adjusted by adding a certain amount of carbon nanotubes (CNT) in the injection molding process. However, injection molding parameters should be arranged carefully due to their influence on electrical properties of CNT-reinforced plastic composites. In this study, polycarbonate/CNT nanocomposites, having three different CNT concentrations (1, 3 and 5 wt%), were produced and injection molded by using three different injection temperatures and speeds to investigate their influence on electrical resistivity. It was found that the electrical resistivity was influenced greatly by the injection temperature when 1 wt% amount of CNT was used in the nanocomposite. However, the effect of injection speed was negligible.Publication Metadata only Performance of Novel TWO-CAP (Thin-Walled Open Channel Angular Pressing) Method on AA5083(KOREAN INST METALS MATERIALS, 2021) KENTLİ, AYKUT; Sahbaz, Mehmet; Kentli, Aykut; Kaya, HasanNewly developed severe plastic deformation (SPD) method TWO-CAP was applied to AA5083 to increase its mechanical properties. The method was developed to obtain the structural beams which have a thin-walled open-cross section area in high strength to weight ratio. During the TWO-CAP process, the annealed U-profile specimens will be pressed along the specifically designed die channel with the help of the hydraulic press machine. After the expansion and narrowing processes, the specimen leaves the die with initial dimensions at the end of each pass. Therefore, the material gains strength, hardness, and toughness while the microstructure of the material was improved as a result of the SPD. In order to determine the effect of the TWO-CAP on the mechanical properties of the material, the hardness and tension tests were carried out on the all passed specimens. Also, the characteristic investigations were performed on the specimens by using optical microscopy, SEM-EDS, and XRD analyses. Graphic Abstract
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