Numerical study of the three-span shaft critical speed and develop a new method to compute critical speed

پذیرفته شده برای ارائه شفاهی ، صفحه 1-11 (11) XML اصل مقاله (1.38 MB)
کد مقاله : 1001-ISAV2022 (R1)
نویسندگان
1گروه مهندسی مکانیک، دانشکده مکانیک، دانشگاه صنعتی شریف، تهران، ایران
2گروه مهندسی مکانیک، دانشکده مهندسی مکانیک، دانشگاه صنعتی شریف، تهران ایران
3گروه مهندسی مکانیک دانشکده مکانیک دانشگاه صنعتی شریف ، تهران، ایران
4گروه مهندسی مکانیک، دانشکده مهندسی، دانشگاه زنجان، زنجان، ایران
چکیده
Critical speed is one of the most important characteristic features of rotating machinery. If the running speed of machinery is matched with critical speed, vibration amplitude increases until severe damage results in the machine. By increasing the constraints of the rotor shaft system, the complexity of calculating the critical speed is increased. In this study, a new method based on finite element analysis (FEA) is developed for the computing critical speed of the machinery with four bearings (supports). The modal analysis by FEA is selected to calculate the natural frequency of the shaft. In this regard, FEA is implemented in the experimental setup, and results are compared to verify the validity of the model. The FEA analysis is used for several case studies for different shaft lengths. By validation of the FEA model, it is used to develop a new method for the calculation of the rotor shaft critical system. In the developed method, four equations were derived for four ranks of critical speed. Briefly, the developed method is an algorithm in which the entrance of its mechanical properties of the shaft and its output is four ranks of the critical speed. It will be shown that the first natural frequency of the three-span shaft varies from the fixed-fixed shaft with the length of the middle span to a simple support beam with the length of the middle span shaft. The output of this study helps to calculate the natural frequency of the three-span shaft in which the close solution is complex.
کلیدواژه ها
موضوعات
 
Title
Numerical study of the three-span shaft critical speed and develop a new method to compute critical speed
Authors
Hassan Izanlo, Mehdi Behzad, Ali Davoodabadi, Hesam Addin Arghand
Abstract
Critical speed is one of the most important characteristic features of rotating machinery. If the running speed of machinery is matched with critical speed, vibration amplitude increases until severe damage results in the machine. By increasing the constraints of the rotor shaft system, the complexity of calculating the critical speed is increased. In this study, a new method based on finite element analysis (FEA) is developed for the computing critical speed of the machinery with four bearings (supports). The modal analysis by FEA is selected to calculate the natural frequency of the shaft. In this regard, FEA is implemented in the experimental setup, and results are compared to verify the validity of the model. The FEA analysis is used for several case studies for different shaft lengths. By validation of the FEA model, it is used to develop a new method for the calculation of the rotor shaft critical system. In the developed method, four equations were derived for four ranks of critical speed. Briefly, the developed method is an algorithm in which the entrance of its mechanical properties of the shaft and its output is four ranks of the critical speed. It will be shown that the first natural frequency of the three-span shaft varies from the fixed-fixed shaft with the length of the middle span to a simple support beam with the length of the middle span shaft. The output of this study helps to calculate the natural frequency of the three-span shaft in which the close solution is complex.
Keywords
shaft critical speed, finite element analysis (FEA), Natural frequency, three-span shaft
مراجع
<p dir="ltr">1. Muszynska, A., Rotordynamics. 2005: CRC press.</p> <p dir="ltr">2. Vance, J.M., F.Y. Zeidan, and B.G. Murphy, Machinery vibration and rotor dynamics. 2010: John Wiley &amp; Sons.</p> <p dir="ltr">3. Childs, D., Turbomachinery rotordynamics: phenomena, modeling, and analysis. 1993: John Wiley &amp; Sons.</p> <p dir="ltr">4. Vance, J.M., Rotordynamics of turbomachinery. 1991: John Wiley &amp; Sons.</p> <p dir="ltr">5. Huang, Z. and Y. Le, Rotordynamics modeling and analysis of high-speed permanent magnet electrical machine rotors. IET Electric Power Applications, 2018. 12(8): p. 1104- 1109.</p> <p dir="ltr">6. Singhal, S. Vibration and rotor dynamics of large high-speed motors driving compressors in the oil and gas industry. in 2012 Petroleum and Chemical Industry Conference (PCIC). 2012. IEEE.</p> <p dir="ltr">7. Nguyen-Sch&auml;fer, H., Rotordynamics of automotive turbochargers. 2015: Springer.</p> <p dir="ltr">8. O&uml; zgu&uml; ven, H.N., On the critical speed of continuous shaft-disk systems. 1984.</p> <p dir="ltr">9. Swanson, E., C.D. Powell, and S. Weissman, A practical review of rotating machinery critical speeds and modes. Sound and vibration, 2005. 39(5): p. 16-17.</p> <p dir="ltr">10. Zajaeczkowski, J., Stability of rotation of a motor-driven shaft above the critical speed. Journal of Sound and Vibration, 1998. 209(5): p. 857-865.</p> <p dir="ltr">11. Jalali, M.H., et al., Dynamic analysis of a high-speed rotor-bearing system. Measurement, 2014. 53: p. 1-9.</p> <p dir="ltr">12. Someya, T., et al., Journal-bearing databook. 2013: Springer Science &amp; Business Media.</p> <p dir="ltr">13. Ramsey, K., Experimental modal analysis, structural modifications and FEA analysis on a desktop computer. SOUND AND VIBRAT., 1983. 17(2): p. 19-27.</p> <p dir="ltr">14. Wang, T., et al. Stiffness and critical speed calculation of magnetic bearing-rotor system based on FEA. in 2008 International Conference on Electrical Machines and Systems. 2008. IEEE.</p> <p dir="ltr">15. Huang, Z. and B. Han, Effective approach for calculating critical speeds of high-speed permanent magnet motor rotor-shaft assemblies. IET Electric Power Applications, 2015. 9(9): p. 628-633.</p> <p dir="ltr">16. Bai, B., et al., Analysis of dynamic characteristics of the main shaft system in a hydroturbine based on ANSYS. Procedia Engineering, 2012. 31: p. 654-658.</p> <p dir="ltr">17. Wang, J.F. and K. Sun. Rotor critical speed calculation based on finite element method of a mixed model. in Advanced Materials Research. 2012. Trans Tech Publ.</p> <p dir="ltr">18. Wang, J.F. and K. Sun. The calculation of the rotor critical speed of turbopump. in Advanced Materials Research. 2012. Trans Tech Publ.</p> <p dir="ltr">19. Bai, B. and L.X. Zhang. A 3-node shaft element for main shaft vibration FE analysis. in Applied Mechanics and Materials. 2014. Trans Tech Publ.</p> <p dir="ltr">20. Jahromi, A.F., R.B. Bhat, and W.-F. Xie, Forward and backward whirling of a rotor with gyroscopic effect, in Vibration Engineering and Technology of Machinery. 2015, Springer. p. 879-887.</p> <p dir="ltr">21. Rao, S.S., Vibration of continuous systems. 2019: John Wiley &amp; Sons.</p> <p dir="ltr">22. Gunter, E., Introduction to Rotor Dynamics, Critical speed and unbalance response analysis. 2001, RODYN Vibration Analysis, Inc. Charlottesville, VA.</p> <p dir="ltr">23. Filippa, C.A., Introduction to finite element methods. University of Colorado, 2004. 885</p>