Did I miss anything interesting about bolted joints? Leave a comment! And remember you can watch the bonus video on joint diagrams on Nebula here - nebula.tv/videos/the-efficient-engineer-understanding-the-joint-diagram

I make a living as an engineer and I can tell you these videos are higher quality than any textbook I had, probably better than any BSME curriculum out there. EXCELLENT work.

As an ironworker, a lot of this goes under our daily radar, but it’s awesome to see the science behind the stuff aside from just slapping the bolt in and walking away. Knowledge like this allows me to do my job better and understand why things need to be done in a particular way to achieve the end goal. Well done.

I used to work in nuclear power and the bolts that hold down a reactor head are about 12" in diameter that need to be torqued to something insane like 1 million ft/lbs. We used a huge hydraulic machine to pre-stretch the bolts and then run down a giant nut. When you release the pre-stretch it generates incredible clamping force, greater than any machine could twist onto the nut!

Watching this gives me great respect for the amount of work that goes into seemingly simple things like bolt joints. I would have never imaged so much nuance.

Don’t know how long it takes to make these videos, but I imagine it takes quite a while because the quality is beyond excellent. Thank you for helping get through Cal Poly Engineering!

Some of the coolest bolted connections were the slip critical joints in powerplants that have to meet seismic code. Things are massive, took forever to rattle them right. The neatest bolts are on the turbine case, feedwater pumps and boiler piping. We don't even use torque wrenches, you can't really because it just takes too much force. Instead we used hydraulic tensioner to stretch the bolt and then spin the nut down. It's at the correct preload when you let the hydraulic pressure off. Another one is really weird. It had a hole drilled down the center for an heating element. Since you can calculate how much the stud will lengthen at a specific temperature you can determine the clamping force when it cools and shortens. Essentially you use heat to make the.bolt grow to loosen and let it cool to tighten. Crazy stuff in powerplants.

Great video. As a designer of gas turbine engines, we never use a critical bolt in shear. The flange is always piloted so that the bolt is only in tension. Also, the bolt should have a lower coefficient of thermal expansion than the flange so the bolt gets tighter when the flange heats up. Bolts are the most over-looked part of mechanical design. I have heard that 80% of the problems at car dealerships are realated to poor bolted joint design. Also, in critical applications, we use a hydraulic bolt stretcher that stretches the bolts the exact amount needed to get the desired pre-load and is much more accurate than using a torque wrench. If you use 4D spacing between bolts (the center to center distance is 4 bolt diameters), you will almost never have a leaky joint. Most engine oil leaks on cars are the result of much larger than 4D spacing because they want to save the cost of the extra bolts and reduce assembly time. Next time you go to Walmart, look at all the oil spots in almost every open parking spot.

Dude, there are so many subtle details in the animation that are kind of amazing. Like at 10:48 when the little windows with the bolt details cast light on the bolts themselves, meaning they are actual objects in the 3d scene with some alpha and emission and they are themselves being animated in and out. Awesome! A lot of people might not consciously register these details but they're really cool.

0:01: Introduction to nuts and bolts 0:34: Assembly process of bolted joint 1:42: Tension joints 4:50: Shear joints 6:45: Bearing joints 8:23: Combined effect of tensile and shear loads 11:04: Controlling preload 13:47: Example of bolted joint in space 14:04: Bolted Joints 14:27: Preload in bolts 15:57: Joint diagram 16:01: Nebula

Exceptional video. I used to work on Toshiba 660 and 720 MW steam generators and this video has given me more of an appreciation for the countless weeks stoning flanges. We used a combination of turn of nut for applying the actual force and measuring the elongation. To turn the nuts we would use an induction heater to stretch the bolt and tap them around with a flogging spanner and I would use an extensiometer (essentially a rod and a dial indicator mounted to a sleeve) to measure the stretch after the bolts had cooled down (usually 12+ hours later).

This is amazing. I'm not even a mechanical engineer, but a computer engineer. But I found this captivating and informative. Thanks you for broadening my knowledge base!

One of my professors used to teach a threaded fasteners course and he mentioned that something like 90% of the tension load on a bolt is in the first 3 threads regardless of the number of threads due to the deformation of the bolt when being tightened

Awesome video! As a few others have said, I would love to see a follow-up episode about washers since now I'm not sure how they work, what they accomplish and what their limitations are.

It's incredible how you managed to converge information that I have gathered and understood for 3 years in such short video! Absolutely fantastic information well done!

Glad you mentioned vibration because I work in aircraft maintenance and sometimes we have to torque check components after the aircraft has flown predetermined cycles numbers. The secondary torque values are noted and sent off to engineering monitoring to establish a resolution, if any

I started watching your videos for studying, but now I watch them for entertainment, they are so good. The animation quality and the information is amazing! I have to present in mechanical design on Wednesday and I based my presentation in your video about fatigue and SN curves

Incredible as always! This was my favorite part of my Design of Mechanical Systems class. Great work, love the animations

They used to call me the "nut factor" back in college

I've been working in structural steel for a while now and this is by far the best explanation I've seen about how bolts work. Even what was tought in school did not come close to the quality if this video ! Thanks for making such understandable videos so people can learn complex topics easier.

Fun fact: Bolts are much less effective if they are not installed. Looking at you Boeing.

visual representation + perfect explanation , really appreciate your hard work 👏

Great video! Very informative, and the animations are wonderful. Keep up the good work!

What perfect timing with this video. We're looking at bolted connections in my steel member design class right now. The slip and bearing portions of this video really helped me.

I liked it before even watching it. Thank you for your hard work and dedication to make engineering so much more enjoyable to learn.

this is a very well made educational video not just for the subject. The way it is made, the richness of content, the pauses, the way to speak, how clear and well pronounced words are, the amazing display with visual representation , the list goes on. Every aspect of the video is well done.

You're back! Fantastic

Excellent video, mechanical engineer for 20 years and some good refresher info, and some things I didn’t know. I wish they would explain bolted joint design this well in senior mechanical design classes.

You are a graphics God ! Those blender animations are certainly taking a lot of time, but the quality is beyond perfect. Keep this up !

Thank you very much ! as a civil engineer student this video is really helped me understand through this semester. Hope you didn't retired making this kind of videos.

Once again, thank you so much. I just finished this video and it has really kicked open the doors for me. I really understand things I should be including in my analysis package now.

This is an excellent video! The animations, organization, and information are all top notch; such an amazing presentation.

This was so awesome.. Now you have me excited for a welds video. Excited to see how you do eccentric weld groups with torsion : )

Never thought I'd be so invested in a video about a bolt, good job sir 👏🏾 👍🏾

Super Good, thanks for all your hard work. Visualizing it made things so much clearer.

This was SO INTERESTING. Thanks!

A lot of first and second year engineering students are going to be watching these. Really good work.

Do note that the use of lubrication may modify the nut factor.

Been an engineer for many year in manufacturing, never specializing this heavily in bolt mechanics, but many times touching on them. Great video!

This has been very informative, thanks!

Rename yourself to The Amazing Engineer.

This was a very informative video, you condensed a whole unit of my post-secondary schooling down to a quarter of an hour. And it all makes sense. This actually makes me want to see your other videos to find out if they're just as enlightening.

Much awaited video. Thanks and kudos to you for the amazing work!!

WOW, my understanding of bolted joints just skyrocketed! Subscribed.

Anecdotally, the elongation I have measured for a given nominal diameter/girth has always been smaller than I expected. I must have forgotten to account for the nut factor

I discovered some of the above simply through observation of bolts used in wooden structures, especially when taken apart and put back together again repeatedly. You can frequently see fatigue issues as the bolts are much stronger than the wood. It's fascinating to see what joints are pushing the capability of the wood/bolt joints, and what joints do not show visible fatigue. I learned all this assembling, taking back apart and reassembling, a backyard jungle gym for the kids as we moved around early in our marriage/family. I should also note that we live in the Midwest and the delta temperature and humidity varied throughout the year. I ended up replacing some of the wood and switching to larger bolts in stressed joints that were also roughed up and glued. The above was used for about 2.5 years before we moved to our newest house which we have lived in now for over a decade. When I took apart the jungle gym the last time, we had to pry the wood apart with a crowbar and no stress was seen in or around the bolts/holes. Thankfully, this was only for those joints that appeared fatigued. I recently inspected the critical joints for visible fatigue and found none. Adults are not allowed to use it, only children, or at this point, grandchildren 🙂

I have been looking for a resource like your channel for so long. I'm so happy to have finally found you!

The clarity of the speech and the quality on animations is amazing.

“The common birthing mechanism uses 16 bolts to connect and create a seal between modules on the ISS. Upon docking, each of the 16 bolts mates with a nut…” this has got to be my favorite sentence and might make me become an engineer just so I can use these terms more frequently.

Hey, Awesome video as always. One comment! Nominal minimum bolt preload for 8.8, 10.9 etc is according to >>>bolt tensile strength

Amazing video, nice job!!

Toolmaker here.......this should be mandatory in any manufacturing apprenticeship program. Fantastic vid!

First time on this channel, and I'm mouth wide open from the quality of this video. Every single aspect is perfect. They even added a 'click' to the torque wrench at 11:30.

Keep up the great content, the amount of effort that goes into these must be immense and we appreciate it greatly.

Thank you for this amazing content. Please make more videos about Machine Elements :)

This is a great summary about bolted joints. Congrats for your work.

thank you for the effort putted in the video

EXCELLENT. very well made video and easy to understand, NOW what I need is a follow up video on the use of washers, lock washers, spring washers, flanged bolts/nuts etc I often see on construction sites of large buildings NO washers are used but a home appliance or small things say a trailer does use them, please explain.

i dont know why im watching this at 1am

Great video, thank you!

Very good explanations, and the visuals are stunning. Perhaps the coolest is that the labels and graphs realistically reflect in the depicted bolts etc

Boeing engineers: make a note of that!

I feel like I just took an entire semester's course in mechanical engineering.

Wow! Amazing explanation! Congrats!

Brilliant video too. Well made! 🎉

This is an incredibly informative video. The talk about sheer force being taken on by the joint parts due to friction force was something I've never even considered before. HOWEVER - please, engineers, please consider renaming K away from 'Nut Factor'

It’s 2am and I have work tomorrow, not as an engineer. Why am I watching this.

Excellent video. Beautiful to watch and very detailed and well explained. Thanks!

This was super interesting and very well animated, loved the video!

Very good video, i would like to add something though. The clamping force of a bolt or nut acts in a 45 degree angle from the tip of the bolt/nut head down until it reaches the end of the material. This is why adding washers with a bigger diameter than the bolt/nut head increases the clamping force. For the most effective clamping strength across a unit, the clamping force ends should be tip to tip with each other.

Sir please do video on what is thermodynamics, Computational fluid dynamics, heat and mass transfer, strength of materials, Kinematics and Dynamics of machines, CAD/CAM

New sub. great visual explanations. I enjoy the straight to the point explanations and no unnecessary comedy or meming.

Such a good video, thank you!!

Amazing content! I love seeing engineering concepts so well animated like this. A super cool added bonus would be to include the angled geometry of brittle fracture along shear plane: _______ | | | | | / | / /| |/ / | / | | | | | --------- Or necking of ductile fracture: _____ | | | | \/ /\ | | | | -------- Thank you for these videos!

Bolt specialist here. As requested, here are my suggestions for improving this video: 1. bolts LOOK simple, but looks are deceiving. There are plenty of subtle details you won't see at first, e.g. bolt-to-joint and nut-to-joint surfaces are often slightly angled to optimize load transfer. Don't call them simple; 2. bolts are not always reusable - see item 8 below; 3. you are correct in mentioning that the joint parts a much less compliant than the bolt. Consider adding that this "much" is typically 3-5 times as stiff for steel parts joined by steel bolts. For aluminium plus steel, the factor smaller - this is one of the reasons why magnesium parts don't combine well with steel bolts; 4. you often say "This is called..." but really, almost all terms you introduce this way have alternate names. E.g. what you call "embedment" is a.k.a. "settling", and the "joint diagram" is often called "clamping diagram". Viewers need to know if they are to learn more; 5. You state that in shear joints, bolts should be "at least two diameters away" from the edge. That assumes typical combinations of materials. On e.g. aluminium parts with 10.9 bolts, I would personally recommend a bit more; 6. I just said "10.9". Bolt strength designations like that one would be a good addition; 7. no, sorry, the turn-of-nut method is NOT easy, at least in mass manufacture. You'll need equipment to measure the angle correctly, especially in safety-critical applications. Plus, it is usually deployed a bit differently than you suggest: first you tighten to a specific torque value, then you add a certain number of degrees of twist. Hence the name "torque plus angle" for this method; 8. you missed the tighten-to-yield method and that's a pity. It works by measuring torque and angle simultaneously, and the bolt is tightened until torque levels off w.r.t. angle. The bolt is now tightened just beyond its yield strength. Second-best possible method out there IMHO, but don't reuse the bolt; 9. best method to date: ultrasonic measurement of bolt lengthening. Dutch company Nedschroef developed this years ago under the name "Nedsonic", taking it from the domain of quality control into line assembly; 10. Final suggestion: take a deep breath now and DON"T FEEL BAD! Your video got quite far, and the points I suggest you add are certainly NOT common knowledge. The assembly industry has a habit of hiding its "secret sauce". Plus, you visualizations are top notch and put almost any textbook to shame. Keep it up buddy ;-)

This is fantastic. Thank you

Great material to refer and refresh about bolted joint. Appreciate your efforts and knowledge sharing.

A couple of related topics that might fit in (and I didn't see in the preview images for nebula) are: how washers affect the load application (during fastening) and load distribution, and types of washers

Great video and animation! You cover many important bits. But, I would have liked to see - no preload with a standard nut will cause the nut to loosen - preload for joints in thin materials is only achieveable with spring washers or bolts with lower Young's modulus Special case as a sidenote: - Preload is hard/impossible to keep when boltign plastik parts together. The plastik will literally "flow" away from the stressed area over time, dependant on it's hardness.

Superb video. Thanks.

Thank you this video was unbelievable. So well explained.

I don't understand how pulling the two preloaded sides apart will not directly influence the stress in the bolt. The pulling apart is in the same direction as the preload. If you don't preload the Bolt and Nut at all and pull the two plates apart the load on the bolt increases proportionally to the external force. EDIT: I get it now... first the preload is reduced and when there is no more preload then all the force goes directly to the bolt. I had to imagine the preload being a lot of small compression springs and the bolt being a tension spring.

the explanation and visualization is brilliant

Amazingly instructive video... it had everything I was looking for. Thank you!

hehe nut factor

Preloading doesn't affect tension joints though! Any tension load applied to the joint must eventually be transmitted to the bolt, so a 10kN load will result in 10kN force in the bolt regardless of how strong you preload it, it's a simple case of following the load path really You're generalizing the case of piping (which require preloading for the sealing of the joint rather than actual structural requirement) to all bolted joints

Concise and informative, Nice!

Thanks for the high quality videos. Better than any textbook available ! Wish these videos were here when I was an engineering student. Keep it up 👍!

Your explanation of clamping force is totally wrong. When you tighten the bolt, the clamping force is equal to the tension in the bolt. if you then try to separate the clamped parts, the parts won't separate until the acting force is becoming larger than the clamping force, but the extra force applied is transferred to the tension in the bolt from the start. So when parts begin to separate, the tension in the bolt is already twice the initial preload.

Had to leave a comment on the quality of this video, fantastic work! Subscribed ✌️

Amazingly clear explanation!

What a fantastic video, thank you.

Just found your channel, subbed, abd so excited you're on Nebula!!

Very interesting and clear information provided through the excellent diagrams, animations and well delivered narrative. I just stumbled onto this video and enjoyed it thoroughly so thank you very much. Through it all I kept thinking about how this applies to rivets.... I don't think you have enough subscribers so I added one of my own with a white notification bell. And a thumbs-up, of course because this analytical mind appreciates this kind of precision when information is being imparted. Well Done.

Subbed! Needed this a long time ago when i went to engineering school! Very clear explaination. Keep up the good work

just awesome explanation, really loved it . a loads of thanks

EXCELLENT video ! 👍

I know nothing of these things, but I'm glad it popped up and look forward to learning more.

What a legend. Fantastic animations

Thank you for linking to the Nebula video in the description, and for making it its own video instead of "bonus content" at the end! This is so much better it boggles my mind that most creators on Nebula don't do it. If there's some sort of Nebula creator forum or the like, maybe you could suggest that others do it this way. It's a much more user-friendly crossover between YT and Nebula (and Nebula, for all that I'm sure it's wonderful for the creators, is pretty abysmal for the users, so it needs all the extra user-friendliness it can get!)