Yazar "Karacay, Tuncay" seçeneğine göre listele

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    Design and performance evaluation of a 3D printed aerostatic bearing concept with high number of micro-orifices
    (Sage Publications Ltd, 2024) Agoren, Gorkem; Dal, Abdurrahim; Karacay, Tuncay
    This study suggests a 3D printed aerostatic bearing concept. The design has a high number of orifices distributed around the bearing to obtain smoother pressure distribution for performance. Inner channels are formed to connect and feed air to each orifice using the advantage of additive manufacturing. The concept is investigated numerically to determine the performance gain of the high number of orifices by calculating bearing stiffness and load carrying capacity. In order to validate the simulation and performance gain an experimental study is conducted by testing Stereolithography (SLA) type 3D printed bearings with various orifice numbers. The bearing stiffnesses and mass flow rates of the specimens are measured, and results are discussed in terms of performance by comparing numerical results. The 3D printed bearings concept has shown promising results in terms of performance while keeping air consumption limited compared to conventional air bearings.
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    Design and performance evaluation of a 3D printed aerostatic bearing concept with high number of micro-orifices
    (Sage Publications Ltd, 2024) Agoren, Gorkem; Dal, Abdurrahim; Karacay, Tuncay
    This study suggests a 3D printed aerostatic bearing concept. The design has a high number of orifices distributed around the bearing to obtain smoother pressure distribution for performance. Inner channels are formed to connect and feed air to each orifice using the advantage of additive manufacturing. The concept is investigated numerically to determine the performance gain of the high number of orifices by calculating bearing stiffness and load carrying capacity. In order to validate the simulation and performance gain an experimental study is conducted by testing Stereolithography (SLA) type 3D printed bearings with various orifice numbers. The bearing stiffnesses and mass flow rates of the specimens are measured, and results are discussed in terms of performance by comparing numerical results. The 3D printed bearings concept has shown promising results in terms of performance while keeping air consumption limited compared to conventional air bearings.
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    Dynamics of a rotor-aerostatic journal bearings system with asymmetric air feeding
    (Springer Heidelberg, 2022) Dal, Abdurrahim; Karacay, Tuncay
    In this study, the effect of the symmetric and asymmetric air feeding on the dynamics of a shaft-aerostatic journal bearing system is theoretically investigated. In this scope, the pressure distribution of the air in the clearance is modeled with Reynold's equation and the lubrication forces are calculated using this distribution. Then, equations of motion derived in four degrees of freedom are solved for different rotational speeds under symmetric and asymmetric air feeding conditions. To validate the simulation results, an experimental test rig comprised of a rotor, air bearings, and measurement equipment is set up and run for different rotational speeds. The nonlinear dynamic behavior of the imbalance responses of the bearing-shaft system is analyzed using bifurcation diagrams, Poincare map, waterfall, and orbit plots. The results of the presented study brought to light that the system has a nonlinear dynamic motion due to a pneumatic hammer. However, the pneumatic hammer frequency of an aerostatic bearing with asymmetric supply pressure condition is lower than an aerostatic bearing with the symmetric condition. And the results also showed that the bearing performance will be improved by asymmetric supply pressure conditions.
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    Performance characteristics of an aerostatic journal bearing with partially blocked orifices
    (Sage Publications Ltd, 2021) Dal, Abdurrahim; Karacay, Tuncay
    Aerostatic journal bearing applications mainly focus on high-speed precision machining, so predictable and smooth functioning of the system is crucial. Air is supplied to the bearing through a number of orifices and any unevenness in the size of these orifices will affect the performance of the system. The size difference could be due to manufacturing error and/or blockage of the orifice because of foreign materials in the air system. In this study, the performance of an aerostatic bearing with a partially blocked orifice is numerically investigated. Firstly, the airflow in the bearing clearance was modeled with Reynolds equation and this equation was numerically solved with the finite difference and differential transform hybrid method to obtain the pressure distribution. Then, the force and the stiffness are calculated from the pressure distribution for different blockage cases of the orifice and different blockage ratios. The results show that the partial blockage of the orifice significantly changes the performance of the system in a positive or a negative way according to the feeding hole position, and the blockage ratio also affects performance.
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    Öğe
    Performance characteristics of an aerostatic journal bearing with partially blocked orifices
    (Sage Publications Ltd, 2021) Dal, Abdurrahim; Karacay, Tuncay
    Aerostatic journal bearing applications mainly focus on high-speed precision machining, so predictable and smooth functioning of the system is crucial. Air is supplied to the bearing through a number of orifices and any unevenness in the size of these orifices will affect the performance of the system. The size difference could be due to manufacturing error and/or blockage of the orifice because of foreign materials in the air system. In this study, the performance of an aerostatic bearing with a partially blocked orifice is numerically investigated. Firstly, the airflow in the bearing clearance was modeled with Reynolds equation and this equation was numerically solved with the finite difference and differential transform hybrid method to obtain the pressure distribution. Then, the force and the stiffness are calculated from the pressure distribution for different blockage cases of the orifice and different blockage ratios. The results show that the partial blockage of the orifice significantly changes the performance of the system in a positive or a negative way according to the feeding hole position, and the blockage ratio also affects performance.
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    Pneumatic hammer instability in the aerostatic journal bearing-rotor system: A theoretical and experimental analyses
    (Sage Publications Ltd, 2021) Dal, Abdurrahim; Karacay, Tuncay
    In this study, the pneumatic hammer instability phenomena in the aerostatic journal bearing-rotor system is analysed and discussed for different feeding hole configurations theoretically and experimentally. The influences of the configuration of the feeding holes on the nonlinear dynamics of the system are also investigated. The air flow between the surfaces is modelled with Reynold's equation and it is numerically solved with differential transform and finite difference hybrid method. Three different aerostatic bearings are modelled and simulated to investigate the influences of the configuration of the holes for different angular speeds. An experimental test rig is designed and tested for different rotor speeds to validate the obtained numerical results. The dynamic response of the system is analysed using waterfall plots, bifurcation diagrams, orbit plots, phase portrait and Poincare map, which are drawn to determine the pneumatic hammer instability region of the modelled system. The results reveal a nonlinear dynamic response of the rotor centre. In addition, the analysis shows that the feeding hole configuration affects the rotor dynamics and the pneumatic hammer instability region.
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    Pneumatic hammer instability in the aerostatic journal bearing-rotor system: A theoretical and experimental analyses
    (Sage Publications Ltd, 2021) Dal, Abdurrahim; Karacay, Tuncay
    In this study, the pneumatic hammer instability phenomena in the aerostatic journal bearing-rotor system is analysed and discussed for different feeding hole configurations theoretically and experimentally. The influences of the configuration of the feeding holes on the nonlinear dynamics of the system are also investigated. The air flow between the surfaces is modelled with Reynold's equation and it is numerically solved with differential transform and finite difference hybrid method. Three different aerostatic bearings are modelled and simulated to investigate the influences of the configuration of the holes for different angular speeds. An experimental test rig is designed and tested for different rotor speeds to validate the obtained numerical results. The dynamic response of the system is analysed using waterfall plots, bifurcation diagrams, orbit plots, phase portrait and Poincare map, which are drawn to determine the pneumatic hammer instability region of the modelled system. The results reveal a nonlinear dynamic response of the rotor centre. In addition, the analysis shows that the feeding hole configuration affects the rotor dynamics and the pneumatic hammer instability region.
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    Vibration Analysis of a Hybrid Polymer Ball Bearing with 3D-Printed Races
    (Springer Heidelberg, 2024) Dogan, Burcu Kucukoglu; Dal, Abdurrahim; Agoren, Gorkem; Karacay, Tuncay
    BackgroundThe use of polymer bearings in some industries has increased in recent years because of their advantages, such as resistance to dirt and dust, no need for maintenance and lubrication, and chemical resistance, especially in hygienic areas. Additive manufacturing (AD) or 3D printing is also a popular method that makes complex geometric shapes easily produced using polymer material, layer by layer, of the defined component.PurposeThe study aims to investigate the applicability of producing polymer ball bearing with additive manufacturing techniques by experimentally observing the bearing's vibrations, temperature, and rolling resistance.MethodsA set of ball-bearing races-inner and outer-are produced with the stereolithography (SLA) method using polymeric resin and tested under a certain load.ResultsVibrations and load cell data for rolling resistance are analyzed through its lifetime to investigate the evolution of the bearing under the test.ConclusionThe additive manufacturing method could be preferred to produce a ball bearing with limited life.
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    Vibration behavior of a 3D-printed hybrid polymer bearing with outer race defect
    (Emerald Group Publishing Ltd, 2024) Dogan, Burcu Kucukoglu; Dal, Abdurrahim; Agoren, Gorkem; Karacay, Tuncay
    PurposeIn industry applications, polymer hybrid bearings have become widespread in recent years owing to the lack of lubricant requirements, particularly in areas requiring hygiene. The additive manufacturing method gives significant advantages to have complex machinery parts, and it has become popular in the industry in recent years. However, it has some inherent disadvantages caused by layered deposition/addition of the materials, and the probability of the localized defect is much higher than in the conventional manufacturing methods. This study aims to investigate the effect of the outer race defect on the characteristics of vibration and service lifetime of hybrid polymer ball bearings produced with the stereolithography (SLA) additive manufacturing method.Design/methodology/approachIn this study, polymer bearings' races were produced with the additive manufacturing SLA method, and the outer race defect was analyzed with measured vibrations.FindingsThe results show that the additive manufacturing method suggests a practical solution for producing a polymer hybrid ball bearing. On the other hand, the hybrid three-dimensional-printed bearing, which has an outer race defect, worked for approximately 8 h without any problems under a 1 kg load and a shaft speed of around 1,000 rpm. In addition, when there is a defect in the outer and/or inner race of the ball bearing, the crest factor and kurtosis of the vibration are higher than faultless ball bearing, as expected.Originality/valueThis paper provides valuable information on the lifetime and vibration characteristics of polymer hybrid ball bearing produced by means of additive manufacturing.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0183/
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    Öğe
    Vibration behavior of a 3D-printed hybrid polymer bearing with outer race defect
    (Emerald Group Publishing Ltd, 2024) Dogan, Burcu Kucukoglu; Dal, Abdurrahim; Agoren, Gorkem; Karacay, Tuncay
    PurposeIn industry applications, polymer hybrid bearings have become widespread in recent years owing to the lack of lubricant requirements, particularly in areas requiring hygiene. The additive manufacturing method gives significant advantages to have complex machinery parts, and it has become popular in the industry in recent years. However, it has some inherent disadvantages caused by layered deposition/addition of the materials, and the probability of the localized defect is much higher than in the conventional manufacturing methods. This study aims to investigate the effect of the outer race defect on the characteristics of vibration and service lifetime of hybrid polymer ball bearings produced with the stereolithography (SLA) additive manufacturing method.Design/methodology/approachIn this study, polymer bearings' races were produced with the additive manufacturing SLA method, and the outer race defect was analyzed with measured vibrations.FindingsThe results show that the additive manufacturing method suggests a practical solution for producing a polymer hybrid ball bearing. On the other hand, the hybrid three-dimensional-printed bearing, which has an outer race defect, worked for approximately 8 h without any problems under a 1 kg load and a shaft speed of around 1,000 rpm. In addition, when there is a defect in the outer and/or inner race of the ball bearing, the crest factor and kurtosis of the vibration are higher than faultless ball bearing, as expected.Originality/valueThis paper provides valuable information on the lifetime and vibration characteristics of polymer hybrid ball bearing produced by means of additive manufacturing.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0183/