My professor says he has been teaching for 25 years (4 years more than my age), but when i attend his lecture, I with my other fellow student understand nothing. Useless 25 years. Thanks to this series of lecture and Dr Hassan. You made me love machine design.Thanks again
Same thing. Asking my teaching professors about that theory, and they said 0. After 4 days of searching an answer I found a brilliant s explanation. Thx a-lot, a Wise man.
Wonderful lecture series by Dr Hassan. It made me to understand difficult concepts in an easy way. Your patience in teaching the subject is commendable.Thank you Dr Hassan for this wonderful lecture.
very very conceptual and informative. He give solid reason of all question.. I dislike MD due to its complexity but sir make me interested in this again..... thank u sir.....
what a nice lecture it is,,,I think it is one of the best lecture all over the youtube lecture on Machine design,,it is really helpfull for everyone,,THANK U SIR SO MUCH
I've read in several books on the subject. I think Norton's explanation is the best, and the way this lecturer presents it is very good. However, everyone says that preload is important as it reduces the load applied to the bolt and shares the load between the bolt and the members. I think this is a wrong say. since the bolt is preloaded, it already carries a load, hopefully more than it should see during its' lifetime. applying a load to the joint relieves some of the stress in the members, but increases the load on the bolt. I think the need for preload lies elsewhere. first of all, its' a means of verifying during assembly that the bolt will hold the service load during its' lifetime. Secondly, during vibration, the preload maintains joint integrity, and does not allow the members to separate. what do you guys think?
Preload adds axial tension stress to the bolt. Yes, it helps keep things together and protects against loosening due to vibration, but it also greatly improves fatigue life. The reason for this is not completely intuitive until you understand fatigue. When a bolt is preloaded, external load adds to bolt tension and reduces member compression, or squeeze. Since a typical member is usually around 4x stiffer than a typical bolt, about 85% of the external load is carried by the members, and only about 15% is carried by the bolt itself. This greatly reduces the alternating load and stress in the bolt, which can significantly increase fatigue life.
Thanks a lot for the video. I have a doubt at 1:08:18 when it was said that "higher the amount of preload, (the better the joint) and the less of the amount of externally applied load will be taken by the bolt". How is that? As I understood, as per the graph of external load assessment the split of the external load is driven by the stiffness of the member and the bolt, which doesn't change. Additionally, during the preload, the forces on both the member and the bolt are the same (one is in compression and the other is in tension though). However, during the application of external load, the deformation will remain same for both the member and the bolt. So, if the deformation remains same (for member and bolt), the external load split shall also be same.
To your first point, it just means that the joint can tolerate more external load before gapping. Once joint is gapped it will take 100% of any additional external load. To your second point, same displacement only means same force if stiffnesses are the same. In this case the compressed flange is far more stiff than the stretched bolt so although they have same displacement the compressed joint reacts far more load than the bolt.
What happens if you use a washer whose inner diameter is larger than the threaded part of the screw itself, but slightly smaller than the screw head? (It seems to me that too much pressure would be located on the outer periphery of the bolt head, but would this pose a serious issue?)
The ID of the washer must always be less than the bolt head diameter. You can check the bearing pressure on the surface of contact simply and compare that bearing stress to the material bearing (best approach) or compression (conservative) strength.
@@bastiancabreramanriquez5131 Then why are there fasteners with bolt-like threads called machine screws? Why are the 1/4"-20 screws called machine screws, but 1/2"-13 bolts are called bolts?
@@bastiancabreramanriquez5131 Still, for some reason, manufacturers tend to use the words interchangeably, for components I'd instinctively call bolts. The main rhyme or reason to this, seems to be that smaller fasteners tend to be more likely called screws. Also seems to have to do with the head geometry, as heads built for external wrenches are more likely to be called bolts, while internal screwdrivers or Allen drives are more likely to be called screws. Screws without standard machine threads, or some degree of self-drilling or threading almost universally get called screws.
Sir,Can we join silicon steel(electrical steel)and pure silicon rod using bolting.will it withstand rotating torque like in rotor part of motor.l need it's information for my research please give reply
Has any considered the need to have equal safety factor for load and separation? The joint has failed the moment there is separation OR load exceed proof load (which ever occurs first). So why not just have both factors np and n0 same? That will lead to your preloading being equal Fi = (1-C)Fp. Isn’t this a better preloading factor to use (1-C) than to bluntly say you must preload to 0.75Fp for reusable Fastners?
Due to uncertainties of the calculations, and the catastrophic effect of joint separation, you want to design for a healthy margin of safety for joint separation. However, bolt static strength can use a margin of safety of near zero (MS=FS-1).
Hello This is a very helpful Video , can you tell me whish is the name of the book that Mr. Hassan was using?. I just saw its from McGrath hill Thanks so much
My professor says he has been teaching for 25 years (4 years more than my age), but when i attend his lecture, I with my other fellow student understand nothing. Useless 25 years. Thanks to this series of lecture and Dr Hassan. You made me love machine design.Thanks again
Thanks for the nice comment.
Same thing. Asking my teaching professors about that theory, and they said 0. After 4 days of searching an answer I found a brilliant s explanation. Thx a-lot, a Wise man.
Wonderful lecture series by Dr Hassan. It made me to understand difficult concepts in an easy way. Your patience in teaching the subject is commendable.Thank you Dr Hassan for this wonderful lecture.
I'd love lectures about gear and shaft design with this teacher
Süper anlatıyorsunuz hocam
very very conceptual and informative. He give solid reason of all question.. I dislike MD due to its complexity but sir make me interested in this again..... thank u sir.....
29:55 shouldn't the sumation on the left also be the inverse? Thank you very much for the video.
Yes, you are right.
37:45 Bolt Strength
what a nice lecture it is,,,I think it is one of the best lecture all over the youtube lecture on Machine design,,it is really helpfull for everyone,,THANK U SIR SO MUCH
You're welcome!
excellent!!! By the way, which book were Dr. Hassan using as reference (according to the slide)? Thanks.
shigley
Sir a huge fan of yours.Really wish to meet you in life.Great concepts.Full of knowledge
I've read in several books on the subject. I think Norton's explanation is the best, and the way this lecturer presents it is very good.
However, everyone says that preload is important as it reduces the load applied to the bolt and shares the load between the bolt and the members. I think this is a wrong say. since the bolt is preloaded, it already carries a load, hopefully more than it should see during its' lifetime. applying a load to the joint relieves some of the stress in the members, but increases the load on the bolt. I think the need for preload lies elsewhere. first of all, its' a means of verifying during assembly that the bolt will hold the service load during its' lifetime. Secondly, during vibration, the preload maintains joint integrity, and does not allow the members to separate. what do you guys think?
Preload adds axial tension stress to the bolt. Yes, it helps keep things together and protects against loosening due to vibration, but it also greatly improves fatigue life. The reason for this is not completely intuitive until you understand fatigue. When a bolt is preloaded, external load adds to bolt tension and reduces member compression, or squeeze. Since a typical member is usually around 4x stiffer than a typical bolt, about 85% of the external load is carried by the members, and only about 15% is carried by the bolt itself. This greatly reduces the alternating load and stress in the bolt, which can significantly increase fatigue life.
Thanks a lot for the video.
I have a doubt at 1:08:18 when it was said that "higher the amount of preload, (the better the joint) and the less of the amount of externally applied load will be taken by the bolt". How is that? As I understood, as per the graph of external load assessment the split of the external load is driven by the stiffness of the member and the bolt, which doesn't change.
Additionally, during the preload, the forces on both the member and the bolt are the same (one is in compression and the other is in tension though). However, during the application of external load, the deformation will remain same for both the member and the bolt. So, if the deformation remains same (for member and bolt), the external load split shall also be same.
To your first point, it just means that the joint can tolerate more external load before gapping. Once joint is gapped it will take 100% of any additional external load.
To your second point, same displacement only means same force if stiffnesses are the same. In this case the compressed flange is far more stiff than the stretched bolt so although they have same displacement the compressed joint reacts far more load than the bolt.
What book does he use ?
What happens if you use a washer whose inner diameter is larger than the threaded part of the screw itself, but slightly smaller than the screw head? (It seems to me that too much pressure would be located on the outer periphery of the bolt head, but would this pose a serious issue?)
The ID of the washer must always be less than the bolt head diameter. You can check the bearing pressure on the surface of contact simply and compare that bearing stress to the material bearing (best approach) or compression (conservative) strength.
@@ToddCoburn Thanks for replying. So far, the thing I mounted holds up!
Dr. Hassan, what happens if we have washers? Does the cone's large diameter change?
I mean if we use SAE washers, you are right, but what if we use a USS Type A washer?
Yes. If you have two washers and two members, you will have 4 stiffness terms. The cone should begin to fan out from the outer edge of the washer.
What textbook are you using?
Please tell me what is the difference between bolt and screw.?
the bolt have an nut, the screw it doesn't have it
A screw has a fine point, bolt doesnt
@@bastiancabreramanriquez5131 Then why are there fasteners with bolt-like threads called machine screws? Why are the 1/4"-20 screws called machine screws, but 1/2"-13 bolts are called bolts?
@@carultch i'm native spanish speaker, so maybe there are differences between the meaning in Spanish and English
@@bastiancabreramanriquez5131 Still, for some reason, manufacturers tend to use the words interchangeably, for components I'd instinctively call bolts. The main rhyme or reason to this, seems to be that smaller fasteners tend to be more likely called screws. Also seems to have to do with the head geometry, as heads built for external wrenches are more likely to be called bolts, while internal screwdrivers or Allen drives are more likely to be called screws.
Screws without standard machine threads, or some degree of self-drilling or threading almost universally get called screws.
Sir,Can we join silicon steel(electrical steel)and pure silicon rod using bolting.will it withstand rotating torque like in rotor part of motor.l need it's information for my research please give reply
Thanks dr. Hassan Rejali
Thank you so much. I have learnt so much. finally understood elementary concepts in bolt design
Nice understanding sir
Has any considered the need to have equal safety factor for load and separation? The joint has failed the moment there is separation OR load exceed proof load (which ever occurs first). So why not just have both factors np and n0 same?
That will lead to your preloading being equal Fi = (1-C)Fp.
Isn’t this a better preloading factor to use (1-C) than to bluntly say you must preload to 0.75Fp for reusable Fastners?
Due to uncertainties of the calculations, and the catastrophic effect of joint separation, you want to design for a healthy margin of safety for joint separation. However, bolt static strength can use a margin of safety of near zero (MS=FS-1).
What a great and helpful lecture I've ever listened to. Thank u to u all.
Happy to help.
Abdulkareem Qasem
يا بش مهندس عبدالكريم،
طلعت تتابع الدكتور حسان...
😙😙😙
الله يوفقك يا بش مهندس ويسهل دربك
Thnk u sir .may ALLAH reward u for this
thank you prof.hassan,it was worth lecture for me as student in ksu (ksa) . and I hopp to be one of your student soon
😘😘😘
We're glad you liked the lecture.
درستها عند شاهد ولا البهكلي ولا فيصل بن يحيى ؟؟
where can i found data on gasket stifness? thanks.
If you can find an approximate E you can calculate the stiffness using the same approach as for washers & other members.
I am screaming the answers to the questions that the Professor is asking hahah. Would have loved to be there. Greetings from Stuttgart, Germany
🤣🤣
very very helpful thanks for everyone who make this beautiful video
awesome very great sir
Thanks
This is way fucking better than my prof…. Thank you!
thanks
Thank you Sir
Find total stress on kutubminar in Delhi so we found next earthquake date from center of earth to the mountain Everest
excellent. thank you for sharing the lecture.
Can someone do a stress analysis of my brain ? Cuz i'm about to burst out
Just add some more bolts.
@@KafkaesqueBrahmins thanks...lol
Hello
This is a very helpful Video , can you tell me whish is the name of the book that Mr. Hassan was using?. I just saw its from McGrath hill
Thanks so much
Who is author of this book? Thanks
i think its shigley
Shigley's Mechanical Engineering Design (looks like the 9th edition)