Part 2 - Critical Speed and Response to Imbalance

[@RotorDynamics]

Your support means everything to us. If you find value in our videos, please consider sharing them with someone who would benefit. Thank you so much!

[@cck0728]

Thanks for your excellent work...I have one doubt....At 00:40 of the video, do you mean by "journal" is the "outer race" of the antifricition bearing? As per this figure, there is some clearance between the ball bearing outer race and bearing housing (that is filled with oil).... Normally, the part of the shaft that is inside the bearing is known as journal (not the bearing outer race).....Can you kindly correct me please? Thanks.

[@RotorDynamics]

Thank you for your kind words and for bringing up a valid question. I appreciate your attention to detail. I can clarify that when I mentioned 'journal' at 00:40 of the video, I was referring to the 'outer race' of the antifriction bearing. Additionally, I recommend checking out Part 26, where the Squeeze Film Damper is covered in detail. It may provide further insights and context to the topics discussed in the video. If you have any more questions or if there's anything else you'd like me to address, please feel free to let me know. Thanks once again for your engagement and valuable input.

[@cck0728]

@@RotorDynamics Thanks....Now it's cleared... Thanks for your excellent work.... Keep it on.....

[@fayefarahmand3375]

Thank you for this video. There are not many KZbin videos on h these kinds of in-depth technical topics.

[@RotorDynamics]

Thank you, Faye. I'm glad you enjoyed my videos. Don't forget to Like & Subscribe. :)

[@samren453]

Thanks for your efforts & videos to pass the experiecne to generations.

[@RotorDynamics]

Thank you so much for the kind words! 🙏 It really means a lot to know that my videos are making a difference and passing on valuable knowledge to future generations. That’s exactly why I started the channel! If there’s anything else you'd like to see or learn about, feel free to let me know. Thanks again for your support!

[@guanjiazhao]

Nice Job! Thanks for your videos.

[@RotorDynamics]

Thank you so much for your kind words and support! I'm thrilled to hear that you enjoyed my videos. It means a lot to me. I'm passionate about creating content that is informative, entertaining, and helpful. I appreciate you taking the time to watch and engage with my channel. Your positive feedback encourages me to continue producing quality videos. If you have any specific topics or suggestions you'd like to see in future videos, please let me know. I'm always open to ideas from my amazing viewers like you!

[@jerardomartinez7855]

1- Balanceo de presicion (Altas velocidades) 2- Girar rotor alejado de zona de la velocidad crítica (o frec. natural). 3-Añadir amortiguamiento en sistema de rodamientos. Excelente gracias!!

[@RotorDynamics]

It's wonderful to hear that you enjoyed the presentation, and we're excited to have you join us for our future videos. Your support is truly valuable to us!

[@ahmed.elrifae]

Great Video . Keep it up. Could you please give us a brief introduction about yourself and your experience?

[@RotorDynamics]

Hi Ahmed. Nice to meet you here. I'm based in the US and working for the industry for 10+ years on bearings and rotor dynamics. I also completed my M.S. and Ph.D. in the field of bearing & rotor dynamics. I hope you enjoy my videos.

[@ahmed.elrifae]

@@RotorDynamics that is awesome What is your email so that we can be in touch ?

[@RotorDynamics]

@Ahmed El-Rifae Hi Ahmed. Sorry for the delayed response. My email address is [e-mail]. Please email me if you have any questions.

[@GeorgePaul-tw8qv]

Thank you for the video. For general machinery, how much difference from the bending critical speed is safe (in engineering)?

[@RotorDynamics]

Excellent question. The separation margin from the bending modes varies based on each company's design philosophy. However, a 20% separation margin is a common target. For more details, please refer to the video in Part 9. :)

[@taerineoppa4832]

Thank you The lesson is very important

[@RotorDynamics]

You're very welcome! I'm glad you found the lesson important. If there are specific topics you'd like to see covered in future videos or if you have any questions, feel free to share your thoughts. Thanks for watching and for your positive feedback!

[@ilyagordievsky9530]

Hi. Thank you for your work.

[@RotorDynamics]

Thank you. I hope you enjoy.

[@verminer7]

I wish you could explain as i think you have the best explaination for resonanace or critical speed. In the case of ship vessels, which shafts rotate due to the internal cumbustion engines. So is it when the cumbustio engine ( EXTERNAL FORCE) forcing the shaft to rotate and when the shaft rotate and the vibration due to this rotations meets the natural rotation of the shaft resonance happen? If that so what is the natural frequency and where is it comming from?

[@RotorDynamics]

Yes, in a ship, the internal combustion engines provide the external force to rotate the shafts that are connected to the propeller to generate thrust and move the vessel forward. The natural frequency of a shaft is determined by its physical properties, such as its length, diameter, material, and shape. When a shaft is rotated, it will vibrate due to the unbalanced forces generated by the rotation, which can cause resonance if the frequency of the vibration matches the natural frequency of the shaft. Resonance can lead to excessive vibrations that can damage the shaft and other components of the propulsion system. To prevent resonance, the shafts are designed with natural frequencies that are different from the frequencies generated by the rotation of the engine. This can be achieved by adjusting the physical properties of the shaft or by using dampers to absorb the vibrations. In summary, the natural frequency of a shaft is an inherent characteristic of the shaft that determines how it will vibrate when rotated. It is crucial to design the shaft with a natural frequency that is different from the engine's rotational frequency to prevent resonance and avoid damage to the propulsion system.

[@verminer7]

@@RotorDynamics Firstly thanks for the swift replay, here isbmy confusion, we need to have two vibrations to equal each other for resonanace, first one i understand (which is due to imbalances in shaft whem it rotates it will vibrates. So this one is initially caused by cumbustion. Now the other vibration which is natural frequency, i know it depends on what kind of material and system. But what causing it or whats generating it. I understood from you that if natural frequency and rotation imbalance frequency equal each other. Resonance occurs. So basicly im asking whats generating the natural freqiency vibration is a metal it self wont vibrate by it self. (Also an engine room in vessel is always vibrating due to other mechaneries also, dunno if this assist you in a way) Thank you again its just very hard to vision it.

[@RotorDynamics]

@@verminer7 Thank you for your message. The natural frequency vibration is generated by the internal structure of the material itself. When subjected to a disturbance, such as the rotation imbalance frequency you mentioned, the material oscillates at its natural frequency. Or other machinery (or other vibration source) in the engine room can excite the natural frequency of the shaft. If there is no external excitation to the shaft, the shaft natural frequency will not excite. Again, the natural frequency vibration is inherent to the material. I hope this clarifies your confusion. :) Let me know if you have any further questions.

[@alexludero680]

Nice Video! Great explanation.

[@RotorDynamics]

Thank you so much for your kind words and for watching my video! I'm glad to hear that you found the explanation helpful and enjoyed the content. If there are any other topics you'd like to see me cover in future videos, please feel free to let me know. Your feedback and support mean a lot to me. Thanks again for watching!

[@bazylinskuns]

Is there a Part 1 video? You have great content but I'd like to start from the beginning

[@RotorDynamics]

Thank you for your feedback. We noticed that the audio quality in Part 1 was subpar, and we will be re-recording and releasing an improved version soon. Please feel free to share any further feedback you may have. :)

[@PcZ-m1v]

Hello sir! Thanks for uploading such a great video！In 3:04 the speed unit is 10 to the negative cube, should it be 10 to the positive cube?

[@Candilaso]

Hello, i am trying to use the XLRotor software but i don't have the password for the installation. The XLRotor hosts are down and I would like to know if you can provide me the code. Thank you

[@JKTCGMV13]

Nice

[@RotorDynamics]

Thanks!