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23 results on '"Karaçay, Tuncay"'

8. Effect of Preload on the Vibrations of EHL Angular Contact Ball Bearings: Theoretical and Experimental Results.

Author

Bal, Hikmet, Ateş, Kerem, Karaçay, Tuncay, and Aktürk, Nizami

Subjects
BALL bearings, NONLINEAR equations, RUNGE-Kutta formulas, EQUATIONS of motion, SIGNAL processing, BEARINGS (Machinery), ROLLER bearings
Abstract

The vibrations of a shaft in rotary mechanical systems supported by angular contact ball bearings are investigated theoretically and experimentally for various preloads in this paper. In the theoretical part of the study, a dynamic bearing model is presented, a rigid shaft supported by EHL angular contact bearing has been modelled as 5 DoF. Non-linear equations of motion are solved numerically by the Runge–Kutta method. In the second part of the study, an experimental setup that enables performing different operating cases has been designed to validate the theoretical results. Theoretical and experimental data are investigated and compared in both time and frequency domains and the results are compared. It is observed from both the theoretical and experimental studies that preload has a significant effect on the vibration behaviour. Results show that the increase in preload reduces the amplitude of the variable compliance frequencies of bearing, the natural frequency of system is shifted to a higher value, and using signal processing with an envelope spectrum gives better results in spectral analysis; small deviations occur between the theoretical and the experimental data due to modulation and noise from machine elements such as gear, motor, misalignment, waviness, etc. Therefore, the presented dynamic bearing model can be used with a reasonable accuracy to examine effect of preload on the vibration of shaft-bearing system. [ABSTRACT FROM AUTHOR]

Published
2022
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9. Radyal basınçlı hava yataklarında yüzey pürüzlülüğünün yatak-rotor sisteminin yük taşıma kapasitesine etkisi

Author

DAL, Abdurrahim and KARAÇAY, Tuncay

Subjects
Engineering, Yük taşıma kapasitesi, Reynold's denklemi, lcsh:TA1-2040, Basınçlı hava yatağı, Mühendislik, Basınçlı hava yatağı,Yüzey pürüzlülüğü,Yük taşıma kapasitesi,Reynold's denklemi,Hibrid nümerik çözüm yöntemi, Yüzey pürüzlülüğü, lcsh:Engineering (General). Civil engineering (General), Hibrid nümerik çözüm yöntemi
Abstract

Buçalışmada, yüzey pürüzlülüğünün, basınçlı hava yatağı ile desteklenmiş biryatak-rotor sisteminin yük taşıma kapasitesine olan etkileri teorik olarakaraştırılmıştır. Bu kapsamda yatak ve rotor yüzeyleri arasındaki havanın akışı,Reynold's denklemi ile modellenmiştir. Bu model içerisindeki, yatak ve rotoryüzeyleri arasındaki mesafeyi tanımlayan film kalınlık fonksiyonu yüzeypürüzlülüğü ile birlikte ifade edilmiştir. Reynold's denklemi DiferansiyelTransform& Sonlu Farklar hibrid sayısal çözümü kullanılarak çözdürülmüşyüzeyler arasındaki basınç dağılımları ve yatak yük taşıma kapasitelerihesaplanmıştır. Yüzey pürüzlülüğünün, basınçlı hava yatakları ile desteklenmişbir yatak-rotor sisteminin yük taşıma kapasitesi üzerindeki etkilerininaraştırılması için, Matlab ortamında bir algoritma geliştirilmiş ve basınçlıhava yatağının geometrik parametreleri ve rotorun açısal hızı için benzetimleryapılmıştır.

Published
2017

10. Performance characteristics of an aerostatic journal bearing with partially blocked orifices.

Author

Dal, Abdurrahim and Karaçay, Tuncay

Abstract

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. [ABSTRACT FROM AUTHOR]

Published
2021
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13. Pneumatic hammer instability in the aerostatic journal bearing--rotor system: A theoretical and experimental analyses.

Author

Dal, Abdurrahim and Karaçay, Tuncay

Abstract

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 ınfluences 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 Poincaré 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. [ABSTRACT FROM AUTHOR]

Published
2021
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17. On the Numerical and Experimental Analysis of Internal Pressure in Air Bearings

Author

Dal, Abdurrahim and Karaçay, Tuncay

Subjects
Air bearing, internal pressure, Reynold's equation, rotor
Abstract

Dynamics of a rotor supported by air bearings is strongly depends on the pressure distribution between the rotor and the bearing. In this study, internal pressure in air bearings is numerical and experimental analyzed for different radial clearances. Firstly the pressure distribution between rotor and bearing is modeled using Reynold's equation and this model is solved numerically. The rotor-bearing system is also modeled in four degree of freedom and it is simulated for different radial clearances. Then, in order to validate numerical results, a test rig is designed and the rotor bearing system is run under the same operational conditions. Pressure signals of left and right bearings are recorded. Internal pressure variations are compared for numerical and experimental results for different radial clearances., {"references":["J., Wang, \"Design of gas bearing systems for precision application,\"\nPhD Thesis, Technische Universiteit, Eindhoven, 1993, pp. 1-35","M., Uneeb, \"Theoretical investigation of whirl instability in externally\npressurized gas journal bearing,\" PhD Thesis, Imperial College of\nScience, Technology and Medicine, London, 1992, pp. 29-92.","J. H., Laub, \"Externally Pressurized Gas Bearings,\" ASME Journal of\nLubrication Technology.,vol.4 (1), pp. 261, 1961.","J. W. Powell, \"Gas behavior and load capacity of hydrodynamic gas\njournal bearing,\" Transactions American Society Lubrication Engineers,\nvol. 6, pp. 11, 1963.","E. H. Dudgeon and I., R., G., Lowe, \"A theoretical analysis of\nhydrostatic gas journal bearings,\" Mechanical Engineering Report 54,\nCanada, 1965, pp. 15-50.","J. S. Ausman, \"The fluid dynamic theory of gas lubricated bearing,\"\nTrans. Amer. Soc. Lub. Engrs., vol. 79, pp. 1218-1224, 1957","W. J. Lund, \"A theoretical analysis of whirl instability and pneumatic\nhammer for a rigid rotor in pressurized gas journal bearing,\" Journal of\nLubrication Technology, vol. 89 pp. 154-165, 1967.","D. Fleming, P. Cunningham, and W, J. Anderson, \"Stability analysis for\nunloaded externally pressurized gas lubricated bearings with journal\nrotation,\" Technical Report TN D-4934, NASA Levis Research Centre,\nUnited States, 1968.","N. Wang and C. Chang, \"An application of Newton's method to the\nlubrication analysis of ari lubricated bearings,\" Tribology Transactions,\nvol. 42, pp. 419-424, 1998.\n[10] K. Czolczynski, \"Mathematical model of a gas journal bearing,\"\nRotordynamics of Gas-Lubricated Journal Bearing System, Springer,\nNew York, pp. 1-48, 1999.\n[11] C. Wang, M. J. Jang, and Y. L. Yeh, \"Bifurcation and nonlinear\ndynamic analysis of a flexible rotor supported by relative short gas\njournal bearings,\" Chaos, Solitons& Fractals, vol. 32, pp. 566-582,\n2007.\n[12] J. Park and K. Kim, \"Stability analysis and experiments of spindle using\nnew type of slot restricted gas journal bearings,\" Tribology\nInternational, vol. 37, pp. 451-462, 2004.\n[13] Y. S. Chen, C. C. Chiu, and Y. D. Cheng, \"Influences of operational\nconditions and geometric parameters on the stiffness of aerostatic\njournal bearings,\" Precision Engineering, vol. 34, pp. 722-734, 2010.\n[14] G. Belforte, T. Raparelli, V.Viktorov, and A. Trivella, \"Discharge\ncoefficients of orifice-type restrictor for aerostatic bearings,\" Tribology\nInternational, vol. 40, pp. 512-521 2007.\n[15] A. Dal, and T. Karaçay, \"Dynamics of Externally Pressurized Air\nBearing with High Values of Clearance,\" in ASME 2014 12th Biennial\nConference on Engineering Systems Design and Analysis. Copenhagen,\n2014.\n[16] T. Karaçay, \"Theoretical and experimental investigation of dynamics of\nrotor supported by externally pressurized air bearings\", The Scientific\nand Technology Research Council of Turkey, Ankara, Technical Report,\nARDEB-1001-112M847-2, Oct. 15, 2014 (In Turkish).\n[17] MATLAB version 7.0.1, 2004, computer software, The MathWorks Inc.,\nNatick, Massachusetts."]}

Published
2015
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