It would've helped if at the end of this video you put up a chart or listing ranking the various bolt types in both shear off strength and linear pull strength, from best to worst, along with all of the associated failure values so we could study and compare all of the results all together, side by side in a list form for at least 30 seconds or so.
No lo puede hacer porque no es la forma correcta de hacer ensayos de rotura de materiales; incluso las maquinas especificas a tal fin realizan la curva carga/deformacion/rotura
Russia has the best titanium in the world... what they use on their spacecraft is the best of that best. The Soviets at one point had a whole giant vacuum fabrication facility to make titanium submarine hulls... it was a giant waste of time/resources but the engineering & fabricating processes still make them the best in the world (like Taiwan with chip production... wherein the most bleeding edge becomes almost Guild Master/Alchemist that can only be reproduced within those labs by those masters who pass on this unlearnable aspect to the head apprentices.) Same reason why everything collapsed in America cause those original labs/fabrication facilities with those old masters were shut down and they have to be essentially built from the ground up again
In a few tests you can see the head of the bolt moving well before any yield, meaning bolt has not been properly torqued. Stresses accumulate differently when you have combined stresses and strains. It is always important to torque to specification. As a design engineer we were instructed to avoid putting bolts in single shear or shear at all. Shear stress in steel is traditionally lower than tensile yield strength. Some preferred practices were not being used in these tests.
Glad that someone else noticed that 😮 You should always double check everything especially if you get a result you didn’t expect, make sure that it wasn’t a fault of your testing.
Bolts are not designed to be used in shear, that’s what pins are for. If they do get used in shear, they should be used in a double shear at the minimum and only the unthreaded portion of the fastener otherwise the bolt will fail at the small diameter in the bottom of the thread root.
Worked for a foundry that produces areospace/medical titanium parts. Some of the suppliers where chinese, they produce good materials. Only issue with the cheaper bolt is the coloring, it indicated the presence on alphacase on the surface of the parts. Alphacase is very brittle so it cause problems for cyclic loads overtime (small cracks will form and weaken the part). Alphacase is formed when titanium is heated since it reacts with oxigen. Alphacase needs to be etched off the surface using hf acid for a quality part, the coloring indicates that the etching process was not properly done. Hope this info helps/clarifies for someone.
My biggest criticism is that you kept mixing up the comparative values on the screen. For example at the end you tested the Chinese titanium then put up the value for the grade 8.8 bolt but labeled it Titanium for Spaceship. Then again when you tested the 12.9 bolt you put up a different value but labeled it Titanium for Spaceship again.
It's not friction, it's applying the proper preload for the fastener to perform as it's designed to. That said this entire "test" has so many sloppy variable that it can hardly be considered reliable. XD
...so does the wallowing out of the holes after each test putting the different bolts in different shear and bending situations...OK vid for a goofy comparison but must list the type and grade of the bolts correctly - so thumbs down
way back now but one of the things they taught new crew chiefs going into the US military was the different forces applied to fasteners, structural components and what those forces look like in action.
Every technology lab has extra equipment for pulling or shearing forces and doesn't play in the garage with old press lol these are standard tests in the industry
"Do not repeat at home". Thanks for the warning, I might have been tempted to try this on the industrial hydraulic press I happen to have lying around 😂
Nice job setting up the rig for your tensile strength test. Two things would’ve been nice to see: 1) during the sheer test, that the initial loading for each bolt was uniform. You could’ve done this with a torque wrench. 2) also very much would’ve like to have seen a close-up shot of the broken surface
For people wondering why cheap Chinese bolts might be stronger than the space bolts - the main attribute of a space bolt would be its weight over its strength. The bolt would rate just as strong as it requires to avoid being disproportionately strong for its needs, thus: heavier than it could have otherwise been. You can bet the bolts were manufactured exactly within strength capability witin specific thresholds, in order to allow for as much enhanced weight reduction property as possible.
This is the absolute correct answer. I've worked with aerospace stuff and everything boils down to the exact required strength to weight ratio. No overkill can be afforded with them otherwise they wouldn't make it off the ground. Everything is calculated down to the nm
Thread pitch, bolt diameter, the torque used to assemble your fixture, the exact alloy of each bolt , the rigidity of the testing fixture, etc. all come into play here. I guess what I'm saying is that it would have been nice to have some more control metrics used and displayed in your video (besides bolt mass and general material type).
I work on metal stamping dies, and we use 12.9 bolts as standard. I've used some supertanium bolts and have never had one fail, but one of the key issues to consider is the diameter of the fastener being used. Often, the best solution is stepping up to the next size bigger. When breakage occurs the designed fasteners might not have been enough for the load Really like this type of video, a final chart on a dry erase board comparing results, would've been nice.
I have used inconel X-750 for a forging die ejection pin mechanism. All imported from China. It worked beautifully. Toolig lasted for nearly 2 years in production. The pin it self was 16 mm in dia and 150 mm in lenght. Die operated at 500 C. had cooling and heating cycles too. Best part, the pin was 1/4 the price an American company quoted me.
Yes, I'm working as an Engineering staff, and we design machines, and yes in drawings, the plans, we use diameter 7 for a bolt of M6 for the same issue you've stated
It's a useful point that instead of going up a fastener grade simply go to the next diamater. It's pretty much an axiom saying that if breakage occurs then the fasteners were not enough for the load ;)
Bravo!!! Class 12.9 bolts are often used when prolonged use under harsh loads risks stretching the bolt rather than breaking it which is why very specific torque settings are required, A good example is Cylinder Head bolts on an engine that need to expand/contract and still remain tight avoiding cylinder head failure :-))
Days of 12.9 class bolts on cylinder heads are gone. Most cars of current century use 8.8 class bolts for cylinder heads. Torque spec is close to yield limit of bolt, so bolt acts as a spring and provides more consistent clamping force under different temperature related expansions of cylinder head
I have a question about those shear tests. Did you torque them to spec for specific steel or titanium and have the same torque specs for each? Only asking because the bolts are much stronger when torqued when applying to sheer strength. I believe tension strength is improved as well but I haven’t specifically looked into that in the past.
Haven't read all the comments but some bolts have threads at the gap between the two plates and some are solid, no threads. Threads will weaken the bolt in shear at the thread compared with the unthreaded shaft of the bolt.
The shear test should be done with a flat peace of steel between 2 supports, torqued with A torque wrench. This will give you 2 shear areas, but no momentum on the screws. Also the friction between the plates will be identical fir comparison. I believe in the first test the chinese titanium screw showed a better value because it was not only applied with shear force, but also with tension because the plate was already pushed away…
Truly unfair comparison. Space bolt had washers (clearly softer metal) and a nut adding leverage against bolt. Fastening nut should be flush as with chinese titanium bolt.
I remember QC testing 12.9 fasteners in the tensile test, the machine would hop about 4 inches off the ground when it would break and it was a damn heavy machine. Another test QC would do was tap a 1/4 plate with multiple holes and screw bolts and screws into it and torque them down to a certain over loaded level and leave them for a week, sometimes the head would pop off and shoot across the room.
My father was an commercial aircraft mechanic and salvaged a lot of the fasteners that were replaced. We used them on various mechanical projects and automotive uses like exhaust bolts. Whatever materials they were made of, they never rusted or stripped, super strong.
A bloke I knew worked for Scania (trucks) and he kept some bolts and stuff. You could put a spanner on those and screw them into the appropriate sized hole in steel and not bother tapping a thread first! They don’t rust and you can’t weld them (accidentally got too close to one bolt but the weld didn’t take).
@@East-somewhere i just claimed they were 'seemingly' indestructible...nothing is indestructible...there is always something bigger, and stronger, or smaller and more pervasive...i prefer to not grasp reality at all since the fundamental state of reality is to always change.
Space bolts look to have an MSO2 coating, whilst the Chinese version have an anodised finished. This wouls prevent hauling and ensure that when torquing the correct preload is induced. No lubrication can weekend the bolts ability to take a load.
Would second an interest in seeing the failed bolt surfaces - a ductile failure of the bolt compared to striping the thread is an interesting comparison. I'd also be very interested to see polished and etched microsections - how do the compositions and heat treatments (obviously, if any) vary? Even the quality of the machining on the thread would be an interesting factor, though I'll admit that's probably too much effort for a RU-vid video.
I think that when you do your tests you should get a torque wrench and torque the bolts to a specific torque. Because it may make a difference if the bolts are not torqued the same. That would make your video's more accurate.
You shouldn't forget that titanium alloy was designed to stay stable under high and low temperatures when most types of steel become more brittle or plastic.
These relatively tiny bolts are incredibly strong is what I get from this video. Even the smaller ones take almost 2 metric tons of force to break. That’s about the weight of a mid sized pickup truck like a Chevy Colorado or Toyota Tacoma.
The torque in to the bolt is a very important variable to the resistence of your assembly. A 10.9 class bolt may resist much less than a 8.8 (same dimensions) if not enough torque is given.
This content wasn’t meant to show a “fair” comparison apples to apples. It was “engineered” to showcase Chinese quality and change perceptions of Chinese metal parts being of inferior quality. This is a PR piece.
Would be cool to see this done with better controls. All bolts same diameter. Same threads. Torqued to the same spec or maybe “optimal” spec for the given material.
Just wondering, what is the rate of metal fatigue for both alloys? The weight and that should be the biggest factors for choice using it in a space craft
I appreciate your test. It would be great to test three different ARP bolts. The 8740, the 2000 and the L19. It would not be comparing the ARP bolts to other kinds or brands, so maybe the legalities are reduced.
The only downside to Ti bolts is that you need cadmium free tools to work on the Ti parts or else the cadmium corrodes the Ti. I worked at Viking Metallurical Corp, they make Ti jet engine parts and learned about this gift from space.
Shocked that the AliExpress bolts performed as well as they did. I figured they'd be filled with rabbit turds or something (like fake cigarettes a few years ago).
@Baldspot My dad was born in the 50's and he never heard that "Made in Japan" meant junk. Although you are right, the West underestimate China way too much.
I think that quality itself isn't necessarily the issue when the product in fact matches the description of the seller on AliExpress. The problem is that regulation on such platforms is often bad, so there is no guarantee that a titanium bolt is indeed made of 100% titanium.
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Wow what a surprise that fatmericans are xenophobic racist twats.
Great fun to watch. Thanks for such an interesting comparison of the strength of bolts made of different metals both by way of lateral tension and shear force
Hmmm so.. different bolts of different materials, size, width and torque applied to will have different strenghts. How accurate this test was ! I am amazed !
You should have used a torque wrench for this experiment, in order to compare fairly these bolts. When tightened adequetly, all the cutting force turns to traction tensions. Failing to evenly torque bolts, could lead to uneven results
I think it's not the head type but the grade of titanium used. Regardless of what the the tightening interface is it's more that this will be the same material type.
I use the Chitanium bolts for the DB killer on my bike. The T30 bolts show no signs of strippage whereas the 4mm hex bolts that they replaced where dangerously close to stripping after two track days.
only problem was the sheer point on space shuttle bolt was more than double the other bolts due to shallow thread length had to space with another nut and a bunch of washers pushing sheer point way out effectively making a fulcrum
A better comparison would be to use two bolts of equal weight rather than the same size. That would show the relative strength vs weight. Titanium has an advantage in being lighter and does not rust, even in saltwater.
This is what Dad did when he worked on the Titan IV rocket platform at Cape Canaveral. He was responsible for the stress analysis of the bolts for the launch assembly. The Cassini spacecraft was one of his projects.
Don't just compare values of force applied on each bolt. They can be of different cross sectional area. The strength value should be in psi (pounds per square inch of cross section area) of shear, tension or compression.
Been heard titanium is weak on impact and good at handling high heat, so the test result is more than I expected. And I wonder, doesn’t the manufacturer give the standard, of how much force the bolts are designed to handle? …
Years ago a surgeon in Hawaii found out right before surgery that he didn’t have the titanium rods he needed. He went to the auto parts store and bought titanium screwdrivers and hacked off the handles. The rods he inserted ultimately failed and after the next surgery to replace them the doctor tossed the inferior rods but a nurse retrieved them and turned them over to authorities. The patient was very elderly. I remember thinking that this guy went through too much to get to the position of a surgeon and then just shanked it. Like is a race to see if you die of natural causes before you really screw up something.
А условие одинаковой осевой затяжки деталек при тесте на "срез/смятие" в отверстии соблел? нет тогда по деталям машин садись 2, усилие затяжки повлияет на силы трения которые надо будет сначала "преодолеть" так еще и пары трения титан сталь не равны между собой по умолчанию, потому что тест на растяжение показал совсем другой запас прочности + гайки тоже надо брать равного класса, чтоб смятие витков было аналогичным с болтом, а то будет как с 12.9 - витки гайки остались на "дико каленом" болту, которые вообще запрещены в машиностроении, так как "лопаются" а не тянутся в случае разрушения, а так для обывателя "красиво", спасибо за ролики)
12 й класс закален и подвержен определенному отпуску, такой болт не хрупкий, но имеет повышенный предел текучести (0.9) относительно сопротивлению на разрыв, и сталь в таких болтах как минимум 40Х, а это уже не ст3.
Not only is weight reduction considered, also the strength characteristics at the extreme temperatures regarding outer space and re-entry. Grade 8.8 bolts become very soft at only 800-900 degrees F., Very brittle below -100 F.
6:31 this is not a proper test for bolt tensile strength. You used a thin section but that is not intended to hold loads for tension. From the video you can see that the threads are sheared. When you have a booted connection in tension, the threads and nut should never fail. Only the bolt shank (grip) should fail. Again, you need to use a proper tension but for this test. In the following segment you realized it and then used a different nut and the test right broke. It needs a bit of explanation to the audience.
High quality steel with the right hardness is still stronger than the best titanium alloy, titanium is used for weight reduction and corrosion resistance without giving up to much when it comes to strength.
@@andreasfjellborg1810 You are right. my boss at a titanium forging plant used to say "CP-Titanium is only as good as 316 Stainless in strenght but with much lower weight. There are stronger metals, such as nickle alloys that will beat titanium any day in strenght.
Some values worth taking into account: oxidative stress, heat stress and how both of those affect elastic and plastic deformation. I imagine the space use titanium can handle both values better than the cheap titanium as that is the environment they need to be designed to tolerate. (High G stress and atmospheric friction).
High G stress and atmospheric friction HAVE ZERO to do with anything regarding these bolts. In fact high G stress isnt even a thing regarding mechanical fasteners. Its got to do with a persons ability to withstand high G's. Atmospheric friction..lmfao you dug deep for that nonsense. We dont engineer nor test bolts factors that do not apply. Ask me how i know.
Other factors to consider is that this is a room temperature test. Titanium performs better at high temperatures than most steels do, the intended use is another factor in decided which material is appropriate. Titanium is also less susceptible to most types of corrosion than steel is.
I would have liked to see the same tests with you torquing them to the same spec. With and without anti seize or another thread prep. Very cool though.
Not necessarily, the space bolts probably have more focus on being lightweight, performance under a wide range of temperatures and so on. The china ones while admittedly did better than expected, weren't designed to meet the same specific criteria. Only way to settle this now is we get a hydraulic press into orbit...
Can we just appreciate how strong all the materials are? I mean you can pretty much hang an SUV on one of those bolts and they are not even some big and thick ones.
The beauty of steel and alloy products are their tensile strength. If you could hold onto it, several people could hang from a coke can, though one heavy foot is enough to crush it. Of course, concrete is the opposite, which is why they are a brilliant construction product when combined.
Thats not how titanium works, titanium is lighter than steel, but similar strength, the aliexpress bolts arent oure titanium and have other alloys in them to make it cheaper to produce, but they are about the same weigh as steel, not titanium, making them useless
Dans un assemblage mécanique il faut toujours créer un "point faible" ,c'est souvent les vis et les boulons qui sont prévus pour casser avant que les contraintes abîment des pièces plus chères où plus complexes. Il vaut mieux casser une vis à 10 euros qu'abimer un carter à 1000 euros sur lequel elle est vissée.
Steel alloys are stronger than Titanium, it's just that Titanium has good strength-to-weight ratio. Also, strength does not omly depend on the metal used. It also depends on the manufacturing method (cast, forged, powder-metal forged, machined forged billet, sintered, etc.)
The Chinese bolts sold on ebay/ aliexpress are normally grade 5 which is 6% aluminum and 4% vanadium. The chinese also sell the grade 2 titanium bolts. Which is not an alloy and is dull grey color.
