VIBRATIONAL ANALYSIS OF CANTILEVER ROTOR              IN VISCOUS MEDIUM     Under the expert guidance and mentorship of   ...
INTRODUCTION-CRACKS IN A                          SHAFT/BEAM   Presences of cracks in rotating shafts are serious threats ...
PRACTICAL APPLICATIONS OF CRACK                   INVESTIGATION IN SHAFTS AND                              BEAMSThe analys...
OBJECTIVES OF THE PROJECTThe phases of the process plan for the present Investigation are as follows:• Dynamic analysis of...
IMPORTANT THEORIES AND                    METHODS USED FOR THE ANALYSIS  Cracks introduce new boundary conditions for the ...
IMPORTANT THEORIES AND                   METHODS USED FOR THE ANALYSIS The dynamic response of rotors with transverse crac...
APPARATUS REQUIRED                             An electric motor                            (203v,50hz,0.75amps,          ...
Bearing with housing                                       Dial indicator                        8SCHOOL OF MECHANICAL ENG...
Rotor                             Weight of rotor = 1557.5 grams                                Length of the shaft of the...
Stroboscope                        10SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
EXPERIMENTAL SETUP                        11SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
THEORETICAL CALCULATION                            APPROACH #1Volume of the rotor = volume of the shaft + volume of the di...
APPROACH #1(CONTD.)               Again, wn = (2n + 1)*3.14*C) / 2*l                  wn = 3.14* C / (81.55/100)          ...
APPROACH #2     Now following another approach to find out the natural frequency         Stiffness of any beam is given by...
EXPERIMENTAL ANALYSISWITHOUT CRACK IN AIR1.Deflection in airAt 1446 rpm                  Deflection shown by the vibration...
EXPERIMENT ANALYSIS(CONTD.)2 .Deflection in waterAt 1446 rpm                 Deflection shown by the vibration meter = 0.1...
EXPERIMENTAL                           ANALYSIS(CONTD.)3. Deflection in flour-waterAt 1446 rpm                    Deflecti...
EXPERIMENTAL                             ANALYSIS(CONTD.)WITH CRACK IN ROTOR1. DEFLECTION IN AIRAt 1446 rpm               ...
EXPERIMENTAL                        ANALYSIS(CONTD.)2.DEFLECTION IN WATERAt 1446 rpm                   Deflection shown by...
EXPERIMENTAL                        ANALYSIS(CONTD.)3. DEFLECTION IN FLOUR WATERAt 1446 rpm                   Deflection s...
RESULT AND DISCUSSIONS                                     IN AIR WITHOUT CRACK                2               1.8        ...
IN WATER(WITHOUT CRACK)                2               1.8               1.6               1.4               1.2Displaceme...
IN FLOUR-WATER WITHOUT                                            CRACK                2               1.8               1...
IN AIR(WITH CRACK)                2               1.8               1.6               1.4               1.2Displacement   ...
IN WATER(WITH CRACK)                2               1.8               1.6               1.4               1.2Displacement ...
IN FLOUR-WATER(WITH CRACK)                2               1.8               1.6               1.4               1.2Displac...
CONCLUSION   1)Presence of crack in rotor makes significant difference inamplitude of vibration to that of uncracked one w...
CONCLUSION(CONTD.)   3)Due to the presence of crack, the critical speed of rotor decreases.4)Due to low critical speed the...
FURTHER WORK   1)Bearing characteristics for rotor systems play an important role on its    dynamic behavior, which can be...
REFERENCE          KITO, F., Trans Japan Society of Mechanical Engineering (in                       Japanese), vol. 22, N...
REFERENCE(CONTD.)Crighton,D.G.,Resonant oscillations of fluid-loaded struts, journal of sound                  and vibrati...
THANK YOUWe have been highly obliged to undertake this project as  part of our curriculum for B.Tech and would like toexte...
Upcoming SlideShare
Loading in …5
×

B.tech(Vibrational Analysis)-2012

488
-1

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
488
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
35
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

B.tech(Vibrational Analysis)-2012

  1. 1. VIBRATIONAL ANALYSIS OF CANTILEVER ROTOR IN VISCOUS MEDIUM Under the expert guidance and mentorship of Prof. Isham Panigrahi 1SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  2. 2. INTRODUCTION-CRACKS IN A SHAFT/BEAM Presences of cracks in rotating shafts are serious threats to its performance. detection of crack in rotors needs urgent attention.Precautions should be taken much earlier as crack propagates quicker in rotating shafts due to fatigue loading. Cracks are the major causes of failure, investigation for vibration analysis of rotor with cracks are essential for safe design.Viscous medium, the analysis of critical speed becomes complex. 2 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  3. 3. PRACTICAL APPLICATIONS OF CRACK INVESTIGATION IN SHAFTS AND BEAMSThe analysis of a cracked rotating shaft in viscous medium will be utilized for I )condition monitoring II ) for early crack detection in rotor for vibration of (a) high-speed rotor in centrifuges(prone to fatigue) (b) high-speed boring machine (c) rotors used for drilling oil from sea bedIII) preventing failure of rotors used in machineries subjected to various environmental conditions. 3 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  4. 4. OBJECTIVES OF THE PROJECTThe phases of the process plan for the present Investigation are as follows:• Dynamic analysis of cracked cantilever rotor without viscous medium. • Dynamic analysis of cracked cantilever rotor in viscous medium. 4 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  5. 5. IMPORTANT THEORIES AND METHODS USED FOR THE ANALYSIS Cracks introduce new boundary conditions for the structures at the crack locations. These boundary conditions are derived from the strain energy equation using Castigliano’s theorem. Presence of crack also reduces stiffness of the structures which has been derived from stiffness matrix.Euler-Bernoulli beam theory is used for dynamic characteristics of beams with transverse cracks.Timoshenko Beam theory is successfully used for vibration analysis of cracked shaft. 5 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  6. 6. IMPORTANT THEORIES AND METHODS USED FOR THE ANALYSIS The dynamic response of rotors with transverse cracks rotating in viscousmedium, the amplitude of vibration of rotors are found using Navier-Stokes equation and Fourier transform technique. 6 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  7. 7. APPARATUS REQUIRED An electric motor (203v,50hz,0.75amps, 1/8hp,93w,1350rpm) A flexible coupling 7SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  8. 8. Bearing with housing Dial indicator 8SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  9. 9. Rotor Weight of rotor = 1557.5 grams Length of the shaft of the rotor = 400mm = 40cm Diameter of the shaft of the rotor = 20mm = 2cm Thickness of the disc of the rotor = 15.5mm=1.55cm Diameter of the disc of the rotor = 84mm = 8.40 cm 9SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  10. 10. Stroboscope 10SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  11. 11. EXPERIMENTAL SETUP 11SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  12. 12. THEORETICAL CALCULATION APPROACH #1Volume of the rotor = volume of the shaft + volume of the disc =3.14*40*(2*2)/4+3.14*1.55*(8.40*8.40)/4 =211.6102cm3 density of the rotor = mass of the rotor / volume of the rotor = 1557.5/211.6102 = 7.3602 g / cm3 = 7360.2 kg / m3Theoretically, C = (Modulus of rigidity / density of the rotor ) 1/2 = (80*109/7360.2)1/2 = 3.29*103 m/s . 12 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  13. 13. APPROACH #1(CONTD.) Again, wn = (2n + 1)*3.14*C) / 2*l wn = 3.14* C / (81.55/100) wn = 12.66*10 3 rad/s Therefore the natural frequency is f n = 12.66*10 3 / 2*3.14 fn= 2015.92 HzTherefore the theoretical rpm at which the first frequency occurs is = fn * 60 = 120955.4 rpm. 13 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  14. 14. APPROACH #2 Now following another approach to find out the natural frequency Stiffness of any beam is given by K t = 3.14*G*d4 / 32*l Kt = 3140 Polar moment of inertia of a beam is given by J 0 = density * height of the rotor * 3.14 * (D) 4 / 32 J0 = 1.7 * 10-3 Now to find out wn = ( Kt / Jo ) wn = 1359.065 rad/sec . Therefore the natural frequency is f n = Wn / 2*3.14 fn= 216.411 HzTherefore the theoretical rpm at which the first frequency occurs is = f n * 60 14 = 12984.66 rpm. SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  15. 15. EXPERIMENTAL ANALYSISWITHOUT CRACK IN AIR1.Deflection in airAt 1446 rpm Deflection shown by the vibration meter = 0.05mm Dial indicator reading = 0.1 mmAt 847 rpm Deflection shown by the vibration meter = 0.95 mm Dial indicator reading = 0.9 mmAt 331 rpm Deflection shown by the vibration meter = 1.123 mm Dial indicator reading = 1.2 mm 15 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  16. 16. EXPERIMENT ANALYSIS(CONTD.)2 .Deflection in waterAt 1446 rpm Deflection shown by the vibration meter = 0.18 mm Dial indicator reading = 0.2 mmAt 847 rpm Deflection shown by the vibration meter = 0.78mm Dial indicator reading = 0.7 mmAt 331 rpm Deflection shown by the vibration meter = 1.87 mm Dial indicator reading = 1.9 mm 16 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  17. 17. EXPERIMENTAL ANALYSIS(CONTD.)3. Deflection in flour-waterAt 1446 rpm Deflection shown by the vibration meter = 0.57 mm Dial indicator reading = 0.6 mmAt 847 rpm Deflection shown by the vibration meter = 1.12 mm Dial indicator reading = 1.2 mmAt 331 rpm Deflection shown by the vibration meter = 1.93 mm Dial indicator reading = 1.9 mm 17 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  18. 18. EXPERIMENTAL ANALYSIS(CONTD.)WITH CRACK IN ROTOR1. DEFLECTION IN AIRAt 1446 rpm Deflection shown by the vibration meter = 0.06 mm Dial indicator reading = 0.1 mmAt 847 rpm Deflection shown by the vibration meter = 0.85 mm Dial indicator reading = 0.9 mmAt 331 rpm Deflection shown by the vibration meter = 1.341 mm Dial indicator reading = 1.5 mm 18 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  19. 19. EXPERIMENTAL ANALYSIS(CONTD.)2.DEFLECTION IN WATERAt 1446 rpm Deflection shown by the vibration meter = 0.23 mm Dial indicator reading = 0.3 mmAt 847 rpm Deflection shown by the vibration meter = 0.95 mm Dial indicator reading = 0.9 mmAt 331 rpm Deflection shown by the vibration meter = 1.8 mm Dial indicator reading = 1.8 mm 19 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  20. 20. EXPERIMENTAL ANALYSIS(CONTD.)3. DEFLECTION IN FLOUR WATERAt 1446 rpm Deflection shown by the vibration meter = 1.82 mm Dial indicator reading = 1.8 mmAt 847 rpm Deflection shown by the vibration meter = 1.20 mm Dial indicator reading = 1.3 mmAt 331 rpm Deflection shown by the vibration meter = 0.67 mm Dial indicator reading = 0.6 mm 20 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  21. 21. RESULT AND DISCUSSIONS IN AIR WITHOUT CRACK 2 1.8 1.6 1.4Displacement 1.2 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 Frequency 21 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  22. 22. IN WATER(WITHOUT CRACK) 2 1.8 1.6 1.4 1.2Displacement 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 Frequency 22 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  23. 23. IN FLOUR-WATER WITHOUT CRACK 2 1.8 1.6 1.4 1.2Displacement 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 Frequency 23 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  24. 24. IN AIR(WITH CRACK) 2 1.8 1.6 1.4 1.2Displacement 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 Frequency 24 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  25. 25. IN WATER(WITH CRACK) 2 1.8 1.6 1.4 1.2Displacement 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 Frequency 25 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  26. 26. IN FLOUR-WATER(WITH CRACK) 2 1.8 1.6 1.4 1.2Displacement 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 Frequency 26 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  27. 27. CONCLUSION 1)Presence of crack in rotor makes significant difference inamplitude of vibration to that of uncracked one when rotates in a fluid medium.viscosity of fluid medium increases, the critical speed of the rotor decreases along with the amplitude of vibration.2)Amplitude of transverse vibration of the rotor system increaseswith the increase in the radius of the container carrying the fluid. 27 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  28. 28. CONCLUSION(CONTD.) 3)Due to the presence of crack, the critical speed of rotor decreases.4)Due to low critical speed the damping coefficient increases for which, the dimensionless amplitude of the rotating cracked shaft. Due to low critical speed the damping coefficient increases for which, the dimensionlessamplitude of the rotating cracked shaft is lowest when measured along the crack direction and is the highest in uncracked one for the same type of viscous fluid. 5)External damping has got more impact in reducing the amplitude of vibration than in changing the resonance speed. 28 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  29. 29. FURTHER WORK 1)Bearing characteristics for rotor systems play an important role on its dynamic behavior, which can be incorporated in the theory for higher accuracy.2)Gyroscopic effect which has not been considered in the present analysis can be taken into account.3)Stability analysis of cracked structures can be included in the present study. 29 SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  30. 30. REFERENCE KITO, F., Trans Japan Society of Mechanical Engineering (in Japanese), vol. 22, No. (1956-9), pp663. Iida, S., Trans, Japan Society of Mechanical Engineers (in Japanese), Vol.24, No.141 (1958-5), pp278, 283; Vol.25, No.151 (1959- 3), pp.235. Fritz, R.J., the effects of an annular fluid on the vibrations of a long rotor, part1-theory, journal of Basic Engineering, Vol.92, No.4 (1970- 12), pp923-929. Fritz, R.J., the effects of an annular fluid on the vibrations of a longrotor, part2-test, journal of Basic Engineering, Vol.92, No.4 (1970-12), pp930- 935. Brennen, C., on the flow in an annulus surrounding a whirling cylinder. Journal of Fluid Mechanics, Vol.75, part 1, 1976, pp.173-191. 30 Walson, W.H., O L O F M E C HandI Clark.L.G.,EdynamicKstabilityVofR rotating shafts S C H O Ames,W.F. A N C A L E N G I N E R I N G , IIT UNI E SITY
  31. 31. REFERENCE(CONTD.)Crighton,D.G.,Resonant oscillations of fluid-loaded struts, journal of sound and vibration, vol.87, no.3,1983,pp.429-437.Achenbach, J.D. and Qu, J., Resonant vibration of a submerged beam, journal of sound and vibration, vol.105 (2), 1986, pp.185-198. Shimogo,T. and Krazao,Y., critical speed of rotor in a liquid, Bulletin of the JSME , Vol.25,No.200,1982,pp 276-283. Kadyrov S.G., Wauer, J and Sorokin, S.V., a potential technique in the theoryof interaction between a structure and a viscous, compressible fluid, Archive of Applied Mechanics 71, 2001, pp.405-417.Seeman, R. and Wauer, J., Finite oscillatory motion of a body immersed in an inviscid fluid at rest, and Stochastic Dynamics ,AMD-Vol.192/DE- Vol.78,ASME 1994,pp.135-141. Seeman, R. and Wauer, J., Fluid- structural coupling of vibrating bodies incontact with a fluid, Proceeding 3rd Polish-German Workshop on Dynamical 31 Problems in Mechanical Systems,1993,pp.31-42. SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  32. 32. THANK YOUWe have been highly obliged to undertake this project as part of our curriculum for B.Tech and would like toextend our warmest regards for our Mentor-cum-Guide Prof.Isham Panigrahi and our Respected Dean.Prof(Dr.)K.C.Singh for helping us through the entire duration of the project with their expertise and valuable insights. Group-14 Mechanical Engg Batch:2008-2012 32SCHOOL OF MECHANICAL ENGINEERING, KIIT UNIVERSITY
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×