Critical Speeds for Shafts | Equivalent Center-Lumped Weight | Protecting Against Driven Vibrations

[@mrcoffee315]

Thank you for your videos, they are life saving

[@TheBomPE]

I'm glad you find them useful! Thanks for watching!

[@davidrjoseIFC]

Why not calculate a influence coefficient for the shaft weight? Couldn't be considered a unit distributed load for that purpose?

[@tomasvasconcelos4435]

I can't stress enough how good your channel is! I'm a professor myself, what's that software that you use to draw/write the math? Thank you so much and keep up the amazing work!

[@TheBomPE]

Thanks again for the positive review! (From an expert no less!) I use Microsoft onenote 2007 to do the notes, and camtasia 9 to record the screen and edit. Microsoft messed up onenote for all versions after 2007, so I just keep using that :) Where do you teach?

[@tomasvasconcelos4435]

@@TheBomPE Brazil, Natal. Thanks for the info, I'll try and do the same. I lose too much time organizing the board

[@AJ-et3vf]

Great video. Thank you

[@faizanahmad3351]

i like your videos very much. your teaching style is very good. " I want to ask that how to find second critical speed then third, forth and so on...? " Thank you.

[@TheBomPE]

Section 7-6 of Shigley's Mechanical Engineering Design describes how to do this...it is an eigenvalue problem. We often don't worry about the higher critical speeds when designing shafts, and instead adopt the technique of making shafts stiff enough to avoid even reaching the first critical speed at expected operating speeds. That is why I presented the method shown in this video. Thanks for watching!

[@fabricio6740]

Thanks from Brazil... I see a lot of your videos... So good... Although we have in Brazil a lot of videos about Machine Design, I like to see videos in english because some terms wasn't good translation to brazilian portuguese... The Shigley book in Brazil is very confused...

[@UserUser-we5ho]

I'm using ALL your videos to prepare for my PE exam (not the first one) in a month. THEY ARE OF MUCH HELP. The NCEES manual has different equations specially the beams deflection. The equation used on this video is well known but NCEES uses only the max deflection which is not at the center nor at the single weight location. Any way I can use the NCEES formula for a problem like this one? Also, trying to understand the difference between the f (lineal frequency ) in Hz and w (angular frequency) in rad/s. Much appreciated.

[@TheBomPE]

Good luck on your exam! I'm glad I could help a little!

[@UserUser-we5ho]

@@TheBomPE thanks for your reply. Videos are helping a lot. Do you have a comment regarding the NCEES beam deflection formulas? i found them very limited. Also, the second question regarding the difference between the f (lineal frequency ) in Hz and w (angular frequency) in rad/s. Thanks again.

[@hamdiali631]

what is the name of the book you are using

[@TheBomPE]

I was using Shigley's Mechanical Engineering Design, 10th edition. Thanks for watching!

[@dnachannel7856]

sir but in some case we know the speed of the shaft but dimensions has to find i.e reverse case of your example in that case how can we find that dimensions??

[@TheBomPE]

The most general answer for any scenario like you describe is that we.... ITERATE! My own students generally have mild ischemic events when I say that word, but it is a great general answer. Basically assume a size and evaluate for suitability, then systematically carve it back if it is over- designed. Thanks for watching!

[@dogansahutoglu2073]

Thanks, Micheal. That was very neat...one question: What method to use to find the maximum deflection and its location in this problem? Also, if it was stepped shaft, same formulas can be used?

[@KIMIRAIKKONE198N4]

the same. separate each Area with its cross section. find Wic and Scc considering each section has its own weight and external forces (own I also) this method is a deflection method...got it ?

[@remsycadiente3608]

Sir what reference book did you use?

[@TheBomPE]

I use Shigley's Mechanical Engineering Design. I have two courses that I teach out of this text, and I have a good number of videos presenting this material, organized into these playlists: MEEN361: kzbin.info/aero/PL1IHA35xY5H5AJpRrM2lkF7Qu2WnbQLvS and MEEN462: kzbin.info/aero/PL1IHA35xY5H5KqySx6n09jaJLUukbvJvB Thanks for watching!

[@oneofyk]

hello - is there a way to use this technique if the shaft diameter isnt uniformly constant? or would that require a different method. thank you.

[@KIMIRAIKKONE198N4]

the same. separate each Area with its cross section. find Wic and Scc considering each section has its own weight and external forces. (own I also) this method is a deflection method...got it ?

[@TheBomPE]

If you found this video useful, consider helping me upgrade the old tablet PC I use to create these videos! Thanks! www.gofundme.com/help-replace-my-2011-tablet-pc