ฝัง
- เผยแพร่เมื่อ 9 ต.ค. 2023
- The Titan, a submersible purpose built for diving the 12,500 feet to the Titanic wreck suffered a catastrophic implosion on Sunday Jun 18, 2023 at around 9:30am.
This video shows how the sub looked like on the inside with high detail 3d model animations accurately representing the inner workings.
Carbon Fibre's compressive strength has been inacurately explained as poor in the coverage of this story and this video aims correct this. The amazing compressive strength of the material is reiterated and the load capacity of the hull has been calculated with the help of aeronautical engineer, who has been producing world class competition winning carbon composite gliders for 20 years.
I explain why OceanGate CEO Stockton Rush pursued carbon fiber and the substantial advantages of the hybrid pressure vessel option.
The leaked transcript of text messages between sub and support ship is debunked as a cruel fake.
The role of the real time acoustic hull monitoring system and it failing is explained.
CORRECTIONS:
The water pressure on the viewport is 910 Tons ~ 180 Elephants | Viewport outer diameter 21". 345 sq inch @ 5,800 psi = 910 Tons.
Viewport deflection 3/4" (not 3 1/4")
Further debris recovered • Titan Sub UPDATE: More...
Thanks to Light Turbulence for use of footage • A350 wing flex during ...
Music:
CO.AG Music Sinister Dark Ambient Music - Dark Road • Sinister Dark Ambient ...
CO.AG Over Soon - Background Music • Over Soon - Backgrou...
CO.AG Instrumental Background suspense Music 5 case files • Forensic part 5 Docum...
CO.AG Forensic part 5 Documentary Music • Forensic part 5 Docum...
Sound effects:
Freesound.org
inspectorj_glss-smash-bottle-b, kamilnaidoo23_car-door-slam-sfx, tosha73_transition-car, 560610__arnaud-coutancier__rollers-wheels-3, 257928__kane53126__body-thud, 329915__carmsie__underwater-sounds-loopable, 423798__ch_ase__little-whoosh-3, 415479__ct202__dronefx_4, 162845__beman87__whoosh-in-out-5, 346236__odilonmarcenaro__submarine-sonar-on-modular-synth, 370930__sjturia__refrigerator_hum, 397620__laft2k__wood-creaking, 143279__johnnypanic__btpitchslide, 323384__reaktorplayer__submarine-beats,
0:00 Intro
0:45 Tour
2:36 Bouyancy control
4:05 Water air boundary
6:55 Pressure on the viewport
7:36 Why carbon fibre was a very good idea
8:25 James Cameron starts a false narrative
9:45 Hull 1 and 2
10:35 Fibre alignment
12:15 Glue joint in wreckage
13:04 Failure to test
14:34 Hull shatter
14:55 OceanGate
15:45 Transcript was fake
16:05 Outro
Further debris recovered • Titan Sub UPDATE: More... - วิทยาศาสตร์และเทคโนโลยี
From someone who works around advanced composites in aviation. Carbon fiber composites are strong in their narrow operation limits. Outside of those, stuff is like paper. Additionally, it requires inspections. If not done.... You have a mess just like this.
Still waiting for the official results 🤔
Out of curiosity, how does temperature and torque affect such materials? Not to imply those were a factor here, I am just simply curious. Everyone talks about the tensile strength and the like, but not other things.
@@thatguy9088 well, with bonded materials temperature is a big deal. The glue that holds a composite together can be greatly affected. For example (remember when operated outside its limits) as it gets hot, the glue loses its ability to keep its chemical bond and the composite delaminates.
As for torque, compression, and tension that really depends on the weave and the bias of the fabric in the composite. A general overview hope it helps.
@@shawnhoem487 It does help, thank you. I was just musing on if temperature might play a factor as well. Not in this circumstance, just the material in general. Thank you for your time and thoughts on the matter.
I know from mountain bikes it is theoretically really strong and lite but if there is one hairline fracture the whole integrity is toast. I prefer aluminum it might not be quite as strong but is way more durable
The primary problem with Titan was the temperament of it's creator. Too many corners cut for limited success.
Too many dives with the same vessel was the egotistic mistake, as the main issue in this specific case was that carbon fiber at these pressures gets stressed and over time after so many dives it broke down.
maybe if he had hired more 50 yo white guys, the ones he said he didn't want, cause not diverse enough, he'd still be alive.
@@ElectricalExistence”wokeness” had nothing to do with it. It was Sterling’s massive ego that did them in.
@@CJODell12 whatever bud.
Arrogant, egotistical, fool! Unfortunately he took 4 naive souls with him to an avoidable demise.
I have a family member who holds a PhD physics that has 40 years of experience in carbon fiber development and production. Having designed and built several carbon fiber production facilities all over the globe, I trust his expertise. He told me there was no way he would have ever even gone diving in the deep end of a swimming pool in that "contraption," as he called it, much less down to 12,000 feet. He knew right away based on the construction and lack of attention to detail and safety of the operation that they suffered a catastrophic implosion.
i think it was the dissimilar materials compressing at different magnitudes that made it fail,perhaps he should have just made it 7 tons heavier.
if he had made it properly, perhaps there would have been less issues actually being able to get people to pay him tons of money to dive in it. the only people that did go were, well, fools.
Thank u!
@@ElectricalExistencethere is no way to do this properly. You can not use different materials with different behavior unter pressure to build something like a sub.
common sense alone would tell you multiple, if any dives to bottom is a death wish. that said, im of the limited knowledge based opinion that if they would have dived at more controlled rate the hull may have been up to keeping the 5 alive.. its my undsrstanding that they descended at almost 3x the desired rate. too much pressure increase too soon means the hull saw way too much change in pressure way too quick, flex, shrinkage, warpage all too much too soon. slower dive rate means the hull would have time to acclimate itself *sort of* to the slower pressure changes keeping the vessel from rapidly flexing & ultimately crushing itself to leak status then.... im by no means suggesting that carbon fiber could be used. i have common sense & very little experience with carbon fiber motorcycle parts. im qualified to suggest or recommend anything except objecting to making hulls going to extreme pressure depths made from stale carbon fiber.
I remember seeing the edited videos of the build process, and what stood out to me as a non-expert was the process of bonding the ends to the CF tube; the glue was hand-applied (and the surface apparently not cleaned beforehand), bare hands were touching the CF during the application process, it was not done in any sort of clean-room (lots of dirt and dust in the air), and there was exactly no squeeze-out when each sphere was slid onto the tube, meaning there were almost certainly voids.
Agreed. I wonder if they had significantly extended the flanges on each end and properly glued them if the sub could have made more cycles before imploding. I suspect that might have been the case.
No squeeze out is what shocked me.
That stood out to me as well. This was not the time for handmade structural components.
I agree, glue being the only joint between dissimilar material shear. Should have been pocketed so compression could only push the parts tighter, improving seal and not shear from partial glue failure.
@@strayblackcatsmeowIt WAS pocketed, the titanium flange had a 'U' shaped profile that the carbon fiber slotted into.
The glue is a red herring, because so long as the carbon fiber tube remained intact the end caps would be held in place by water pressure alone.
The real problem with the joint is the shear stress from differential expansion at the point where the titanium 'U' no longer overlaps the carbon wrapped tube. Carbon fiber has negative thermal expansion while Titanium has positive thermal expansion, and carbon fiber is extremely rigid while Titanium has high ductility.
There is also the problem of the differential expansion between the composite overwrap and the inner metal tube, which would cause the tube to shrink faster than the carbon fiber, which would promote delamination and buckling of the individual carbon strands.
Additionally, the pressure cycling in compression would compress the polymer resin matrix of the composite more than the carbon fiber, which would lead to microcracking of the resin when the pressure was released. This would have potentially allowed saltwater to infiltrate the matrix, which could leave salt deposits behind when it was squeezed back out of the cracks during the next cycle. The salt crystals could then induce layer delamination, or even direct shearing of the carbon fiber strands.
After seeing the accommodation, I can honestly say that there isn't enough money or any other temptation humans usually respond on in order to get me into such a ridiculous excuse of a submersible sardine can.
Absolutely nuts.
I have little interest in seeing an old steel ship wreck. The real thrill would be in designing, building, and testing/operating it.
It was a Pipe Bomb basically.. And I think Titanic is a Grave site, no Tourists should get to it. It's a Tomb to hundreds of people.
No point in doing it if you don’t have and assurances that you would survive.
None of that was there, yet they all got in it anyway…
They seemed to of gotten into a mindset of not speaking up anymore and just let him manipulate them without questioning… that right there should have been more than enough to back out.
It was not designed to be a luxury sub so the accommodations are not relevant
@@pazsion 16% of the population has an IQ below 85.
The Titan is really compact now.
I think one of the main issues was the repeated stress on the Carbon fiber. It can only be subjected to these stresses for so many cycles. Also, you have to take into consideration of the four different materials. The carbon fiber, Titanium, the adhesive used and the view port.
Exactly, Those materials all behave differently in such extreme conditions, Bonding them together put extra stresses through eachother..
So one or two dives. Maybe three, then implosion.
Mike, I don't often comment on content I come across online, however I believe you have provided the clearest, most concise yet suitably detailed and realistic summary of what may have happened, with the available information and a solid understanding of materials and processes. It goes without saying that there could easily be a lot more maths and physics to quantify but then this would become a lesson in engineering rather than a clear relatable clip. The perfect balance, and your included animation is second to none. Well done sir!
Thanks. Much appreciate your comment!!
His video is just plain wrong. I’m a mechanical engineer who has experience in carbon fiber and he completely misses the point. There is no counter force from CF tube for the pressures required. Aviation is completely different than this application. MANY engineers warned him and he ignored all of them.
I agree, I've seen about 40 video's related to titan and this is one of, if not the best one I've seen.
Agreed well put together little doco
@@user-wb7ko7kt5o : But completely wrong. Doesn’t matter how professional the video if the info is still wrong. I hope next time he does the same quality video editing, but along with accurate info.
Ive worked with Carbon fiber based competition race cars......it is a fantastic material given its strength and rigidity for the weight. However, every and any material must be tested exhaustively to make sure it is suitable for an application and not just "shell be right mate". Same goes for the attachment methods of the end domes......testing is needed.
indeed! Haas! F1
Yes. I can see how the expense of this thing could cause someone not to want to destroy it, but I would not be comfortable with it until I had pushed it well beyond its target conditions for many cycles. It should have been pressurized, dropped, banged with rocks and things, until one was sure it could handle the loads.
Exactly. In areas it has been used for decades like race cars (as you mentioned), or aviation, they know proper implementation. Oceangate didn't, but they acted like they did.
@@alext3811 re: "In areas it has been used for decades like race cars (as you mentioned), or aviation, they know proper implementation." bingo, i personally was using Carbon Fiber at Agusta Aerospace for the doors of the A109 (ie, the helicopter featured in the first Jurassic Park movie) back in 1993 or 30 years ago as a "mature application", and the material was already in use with NASA and the Military way before that. so see, the problem comes in that those who are "baby young to the world" and have no life experience are EGOTISTICAL and naturally tend to think things were just invented, rather than seeing things properly through a "lens of history".
@@alext3811 re: "Oceangate didn't, but they acted like they did." see Wikipedia entry for FRAUD. also entry for Bernie Madoff/2008 Collapse of US Housing, Beth Holmes/Theranos, Trevor Milton/Nikola, Sam Fried/FTX Crypto, Charlie Javice/Frank, and Elon Musk/Tesla/FSD.
The fact that the flanges at the end failed outwards is a clue to the failure mode of the pressure vessel. I don't agree that it would shatter uniformly like glass. The more likely initial failure is that one part of the cylinder became weaker than the rest and was forced towards the centre by the pressure - this compression on one side would (like if you were crushing a toilet roll) force other sections of the cylinder outwards for a fraction of time before complete failure occurs. That's what ripped the flange apart.
I agree it would not act like glass as it is not glass! That flange blew outwards and the pressure was equalised instantly inside.
You need to listen more. This is why so many half truths are floating around. Because people hear what they want to here. The narrator said that CF fails suddenly like glass does. He didn't say it was glass or that it fractured in the same way. He simply said that it fails without warning which is a property shared with glass.@@tbrowniscool - there is plenty of information on Google as well about how CF shatters into lots of pieces under extreme pressure.
the can of pringles doesn't need to completely shatter for the cap to pop off. this thing was doomed from the moment it was glued together it didn't matter how strong the CF or titanium are the difference between the two creates a gap and that's all the water needs even a pinhole and this thing will tear itself apart at that joint
Yeah all that FIBER Just shattering,? This whole video was incorrect. The flangers were blown out at 1 end. Which just says that the other end was the failure.. And the end with the flash is pushed out is where the air had to go... (the other seam between different materials) ... One failed as an implosion then the other failed is an explosion. Without knowing whether or not the end that has the flange is pushed outward is the front of the back... I would bet that it's the front because they were hearing noises in the back.. That's where the failure happened, Then it pushed the Port hole glass and the flanges out of the front. They must have been Spaghettified instantly when it actually failed. The fact that stockton mentioned the sphincter shrinking noises with the first hull... Leads me to believe the transcript is correct, That as the layers of Carbon fiber were being infiltrated with water and compressed that it failed progressively ...up until a point, after which it was instantaneous. The opposite of a Jack in the Box.
@tbrowniscool LOL... The flange just blew outward? Lol.. (no offense,. But that is funny.) Clearly it blew OUT because the other end blew IN! One end failed imploding, the air had to go somewhere, ... It blasted out the other end! Like a Coup/Contrecoup pattern in Titanium! ❤😊😊
Very well done. As an engineer, I appreciate someone who has the knowledge to present this topic. Thank you.
It is all related to the repeated loading and unloading, this video is well done, those loud cracking during dives cannot be good health signs, if my guess is right, there was some leakage near the end bonds before this failure occurred?
As another engineer I can say this video is pure speculation by someone with limited technical knowledge. No evidence to support his claims. You surely spotted the error he made on the ratio of hoop to axial stresses?
A couple of things, while this Carbon Fiber pressure vessel was being testing out in the Bahamas one day, it was struck by Lightning at least once. Pre-preg Carbon Fiber holds up VERY POORLY to Lightning Strikes as it usually causes serious Delamination's. Unless OceanGate incorporated some proper and well-placed bonding to the entire assembly, and within the CF material itself, there was likely Damages caused by that strike.
Second, Anytime that you're bonding dissimilar materials with Epoxy, like Carbon Fiber to Titanium, you must be absolutely certain there are NO oils or other contaminants on either surface before bonding. Watch the released video of the OceanGate submersible assembly where the technician is wiping a Titanium mating ring w/ a rag (presumably with some acetone) and then handling that same area with his ungloved other hand ? ? ?
Any good NDT Technician (non-destructive testing), or proper X-Ray composite viewer could have found any imperfections, delam's, distortions or defects within the materials used. It's Insane that they fired the manager who pushed for those NDT checks and they drove on so blindly without that assurance.
Edited for spelling and Lightning Strike location.
Those titanium end rings had very little flange on them too. With water pressure trying to squeeze this thing into an hourglass, that also struck me as a very poor design decision. Atmospheric layup with expired pre-preg? I can't imagine how many defects that thing had in it. The biggest defect was Rush.
@@mytmousemalibu Yea, Rush seemed too "over the top" in some aspects, rebellious to ideas that weren't his own at times and behaved like that Salesman who will tell you what you need or want at times. He also had hiring policies that attracted those who were OK w/ stepping outside of normal engineering & maintenance procedures.
I worked in a small R&D group in Seattle in the 80's thru 90's, not far from where these guys were. We were reinventing some very antiquated, 30's vintage, Seafood Processing machines. The Owner/Head of the Co was Genius, happened to be Greek, and was Way out there with his mindset & approach towards how he viewed most things when compared to what most would see.
That trend, of operating outside of the norms, turns out to be what most Genius minds have in common. High Intelligence in people can be very appealing or attractive w/ the "WoW factor" associated with it. It can also border on weird or even dangerous.
Rush had some of those qualities that a Genius might possess but he was also closed minded to ideas that weren't his own. Genius Good, Self centered Bad is my take on the guy. It's just sad how his talents combined w/ his short-sightedness led to the death of others.
Why why why why why WHY was no non destructive inspection done??? WHY WHY WHY
@@nadapenny8592because he wanted to be the McDonald's mass producer of subs. Destructive testing would cost money he didn't have and his company was bleeding red ink as is. Sadly this self assurance of the flawed computer models coupled with his need to succeed caused his death.
@@nadapenny8592 Yea, you can be sure that question will be brought up in the courts. Just as Bizarre were Rush's hiring practices. He intentionally went for new graduate students who were willing to step outside of proven engineering norms and experiment. The Manager who pushed for more thorough testing represented industry standards that Oceangate intentionally avoided. You could almost hear the Attorney's clamoring to represent those lost souls who were victim to Oceangate's methods.
The experimental status that this submersible was allowed to operate under may not have regulatory oversight and that needs to change.
He did not want ultrasound testing on the hull.
To much money for one 2 he knew the second they saw it was junk expired carbon fiber, the test stops right then an he fails
What could possibly be wrong with that. It sounds so typical of the attitude of being “ smarter than everyone else”. It’s suicidal in itself but when you take paying passengers along it’s pure criminal!
Just in his add
a hospital just blew up in gaza but this is what youre freaking out about
@@nutsackmaniaare you going to post that comment on every single video comment section on the whole of TH-cam? Yeh, a bunch of people got killed in yet another war in the middle east, very sad, but if we only ever talk about people killing each other in the middle east we'd have done nothing else for the last 2000 years. Go shout about it on a video that's actually focusing on the war in Gaza, this one is about composite engineering.
Best explanation video i've seen about the titan sub. When they did put the first Titan sub model into the pressure chamber the cf started failing at the titanium dome at that glued joints. Thats why the cf hull was ribbeled appart in axial direction and also tearing appart the small titanium overlap parts. And i very much believe the exact same axial failiure of the cf hull at the glued titatium rings happened again, as it already happened with the test titan in that pressure chamber. There are photos on the internet about that ribbeled-off cf hull. Sorry for bad english. 👯
I'm a layperson without any engineering knowledge, but I like what I'm hearing in this video. It sounds reasoned and I like that credit is given where due, caveats are clearly stated and safety and reliability is upheld beyond all else. I appreciate the expertise and knowledge and background work that has clearly gone into making this video - thank you.
There was a CEO so convinced enough to drag down 4 people with him deep below the sea. Tragic. However the speed of collapsing and death where instant.
I used to haul gravel on barges. When he said that the round port hole had 2700 tons pressure on it I imeaditly thought of a barge loaded with that weight. It would fill the deck area 15 feet high on a barge that is about 180 feet by 45 feet wide. That puts it in perspective.
The big difference between composite and metals is metals can compress at a molecular level under pressure then expend back to normal when the pressure is removed. It can do this repeatedly and engineers can work out how many times it can safely do this.
Composites on the other hand don't compress well because it's not a homogenous material. The carbon fibres and resin have different properties and on top of that, finished carbon fibre is not homogenous like Titanium or Steel. It will have differences throughout the material. Some parts may have a bit more resin, some less, some fibres might be closely aligned while others a little bit further apart.
That doesn't make much difference in normal applications but 4KM down in the ocean under those sorts of pressure, small variations can have enormous consequences for the strength of the vessel as a whole.
It was reported that the carbon fibers’ axial compressive strength is only 10%-60% of their tensile strength and their transverse compressive strength is 12%-20% of axial compressive strength.
Titanium on the other hand, it's compressive strength is more than twice it's tensile strength.
Stockton Rush was a snake oil salesman and he knew that's what he was. He knew he was taking a massive risk with his sub. The structure of his company illustrated this. The holding company was registered in the USA while the company that operated the sub and rented out the seats was based in the Bahamas, thereby avoiding US regulations.
I agree he was primarily a salesman,
so, not being argumentative - i was involved in aerospace when composites first entered. everyone said that nothing would replace aluminum (titanium/steel in empennage/landing gear main spars and stringers) - we witness today, 787 that have mostly solved these issues.
Metals will develop fatigue cracks but that is something you should be monitoring. CF will crack and they heard crackling noises on some test dives. They didn't seem to do enough testing and were overly optimistic about the lifetime of the sub.
@@SuperLordHawHaw an employee was asking to scan the hull and he was fired.
@@prestonburton8504SORRY, BUT your saying is completely NONSENSE... Comparing a composite to aircraft aluminium is wrong, but trying to compare the stress field of an external pressure vessel with the stresses on any airplane is ridiculous. Assuring that, because composites have displaced (SOME) of the uses of aluminium in aircraft, regardless of the resistance to change many years ago is completely wrong. THERE IS A REASON A COMPOSITE PRESSURE HULL IS NOT A GOOD IDEA.
Had me think it was the scrubber that was the culprit for a while there.
😂
lol me too. I think the designer got that tote at a dollar store.
Thanks for a comprehensive and accurate depiction of the flaws built into this vessel. When carbon fiber first came out, we (who worked in composits) were all taught that the 60/30 angle of layup would provide a vastly superior strength. When I first stated seeing similar reports on the tragedy, I figured it had to be a massive error in the laying up of the fiber. You illustrate this perfectly. I also thought his warning system had to be little more than wishful thinking. Lastly, I'm stunned he never utilized NDT like ultra sound. This was a programmed accident. Pride & confidence are not equal to good old-fashioned NDT & destructive testing. Thanks for such a good report. I subscribed. 👍🏻
Welcome aboard.
I agree. The acoustic early warning system was a marketing gimmick and self-hoodwinkery and self-delusion by Mr Rush
I always appreciate your ability to take such complex concepts and communicate them visually and verbally in a way non engineers can grasp these very complex concepts in a more tangible and meaningful way. Thank you for your hard work. I always learn so many new concepts to learn more about.
Working on the development of carbon fibre wide chord aero engine fan blades back in the late 60's, I have some knowledge of the processes and characteristics associated with CF. The development program for the fan blades was the result of the need for a light weight structure, capable of resisting the centrifugal forces on the blade at the tip, as well as absorbing the torquing stresses due to loading. Carbon fibre composite was the only material that met those criteria at the time. unfortunately, it failed the blade impact test, also known as the bird strike test, as mandated by the USA FAA, a nine pound bird fired into the engine running at full throttle, (it passed the UK CAA bird strike test using a seven pound bird). The carbon fibre delaminated, shredded! Years later, General Electric in the US adopted CF for the engines supplied to Boeing on the 777. They experienced the same problem, delamination until they came up with a design which involved three dimensional weaving, with the lay up having cross filaments incorporated in the weave specifically to prevent the delamination, apparently a sixteen hour layup cycle! If the Titan CF centre section had been constructed on the same lines, maybe this could have resulted in a structure capable of withstanding the enormous external pressure. BTW, I dispute carbon fibre composite has good compressional strength, a function of the matrix that binds it together, glue.
😊 Obviously the Engineering wasn't at all sound. A hideous design that wasn't structurally tested. The Carbon Composite cylinder was too long resulting in a deflection near the mid section. The wrapped strands without any overlap with the Titanium Bulkheads was another design flaw. Using this fiber material in any type of loading other than Tension is Idiotic. Throw the potential for an undetected craftsmanship error and you have really Big Trouble. And one more thing, especially for you Carbon Composite Experts, this is similar to Fiberglass for everyone to understand. This isn't all that special. I'll bet you that there won't be another composite submarine any time soon ! One more thing, military submarines have really nice hulls, but they don't go deeper than 2000 feet. Think about that. Titanic is at 12,500 feet.
Ahhh.. as in the infamous RR engines.... that Pilots universally Hate as they can't fully trust them??
do you have any video of the 3 dimensional fiber weaving ? I can not imagine what it could look like. Would be very interesting.
@@superfly3990 It's not necessarily idiotic as CF has a compression strength of roughly 650 Mpa. But titanium alloys that are over 1000 are easy to obtain. Even some steel alloys can exceed this. The issue is weight. But weight isn't really a huge concern for operating underwater. Using an alloy would have been dead simple and done. Of course, leaving many other issues to deal with.
Exactly! Compression strength is good pound for pound but CF's real strength is that the carbon strands absolutely refuse to stretch, but the resin is most of the comprehensive strength. Plastic isnt Exactly known for its compressive strength
The video of them attaching the titanium to the carbon fibre with epoxy smeared on is what gets me. No way to test those resin seals.
The resin to my understanding was just to hold things together above water. Once you get to any depth, or even just underwater, the pressure on the end caps would seal them against the titanium far better than any glue would be capable of.
This scene reminded me of my first silicone caulking job. But then, my project wasn't travelling 4 km down to the Titanic.
Stockton Rush spent more effort on avoiding regulations than he did making sure his craft was safe for passengers. They say hubris is the fallacy of genius.
My claustrophobia is a blessing in disguise. This could never happen to me. I can't imagine wanting to look out that tiny window that you have to share with others.
I had not realized just how cramped it was on the inside, makes perfect sense. But somehow I was picturing something a bit less claustrophobic and horrible. Great video!
There are some videos taken by passengers you should watch.. its crazy tight inside for 5 people
Finally a well researched video that doesn't zero in on the game controller (which was probably the most reliable part of the sub). The truth is that composite construction is commonly used in modern subermersibles. But usually fiberglass instead of CF and rated to shallow depths with a factor of safety of 10+ for both crush pressure and fatigue life, for the very reasons mentioned in this video--this construction is very sensitive to defects and it's hard to both validate the design AND the process without a large sample size to build confidence. And you certainly don't use the sound of fibers snapping to decide it's time to go back up.
Oh, indeed, I concur, on the controller. Baffling to me that something being cheap to purchase is most people's method of evaluating reliability, not the tens of millions of units tested to destruction. Plus, they can afford to keep a few spares in the boat, so even if one of them goes tits up there's others. Baffling.
I'd also be fairly sure that Kemptown Racecourse knew any failure would be instantly catastrophic, and so any kind of safety feature in-dive would be a joke, the sound whatsit etc weren't anything more than a token gesture to calm the gullible, like having a 'main tank explosion' warning light on the shuttle.
"And if the main tank explodes, mate, this little light goes red."
"And then what do you do?"
"Well, then we'll descend to the surface of the earth as a slightly pink mist, in a cloud of very expensive confetti."
Okay, so I will take you up on the game controller - which had little to do with it's general reliability. The problem with using a game controller to operate titan was to do with failure mode analysis. When designing anything which is safety critical, one of the exercises performed is to identify modes of failure and possible outcomes (FMEA). There is no chance the designers of a game controller would have done any such analysis. They wouldn't have been concerned if a single component failure causes an issue as the worst case would be a player losing a game. Imagine therefore if, whilst manoeuvring a dry joint on the circuit board caused a button to jam and rammed the submersible into jagged metal wreckage. Sure they could have a spare controller lying around, but by that point it's not going to matter.
Sure, the military also use game controllers, but I assure you if they ever intended to use them in life critical situations, they will do a full FMEA on it.
From what I have read, there were a lot of other things wrong with this submersible which were much worse than the game controller, but it is a good example of how jerry rigged the whole show was so I don't blame folks for pointing it out.
@@gavinminion8515 That said, there is little to go wrong on the controllers. The main issue is operating in a marine environment. I worked as one of my first jobs as a repair tech and the computers we would get in in from people who lived next to the ocean was.. full of rust and other insanity. One actually had a hole through the motherboard due to condensation causing water to drip down for several months.
@@gavinminion8515OK, cool, interesting point. But...
I'd be pretty damn certain the controller has a good idea what the odds are of button failure, and I'd be fairly certain they're low.
Any controlling device, whether Sony or bespoke would carry such a risk, and Sony have data on hundreds of thousands of units, whereas if you build one for the Titan you have data on one.
You don't actually know if the testing was done by Oceangate, you're assuming it wasn't. I'd agree but it is an assumption.
The outcome of a failure is different, sure, one you lose Tekken, the other you explode, but that doesn't make any difference to the failure mode or the failure frequency, certainly the probability of a failure prone device doesn't kill anyone playing games, but it is going to be a serious threat to the survival of your business. You might not care AS MUCH, but there's a world of difference between caring about losing billions and flat out not giving a shit.
Specific fail point issues seem pretty easy to resolve via software, if concern about a specific button or button emperilising the submersible, you only need one to say 'controller buggered, disregard until this button is pressed again'
I take your point, I do, I just don't see why it'd be less safe to use a device with, by now, trillions of hours of fail state testing instead of building one unique device. It'd be one thing if the controller was being used outside the thing, but the inside of the Tube o Doom was, obviously, well within the normal operating environment. I mean, if the controller hasn't been tested whilst immersed in seawater, that doesn't really matter, because in the condition where it was, you have whole other issues far more pressing. Pun absolutely intended.
What would be the Mean Probability of Failure figure that would be acceptable for this use? Because I'd be absolutely certain Sony exceed that value, and equally certain it would not be possible to generate such a number with a bespoke unit.
In any case, it is at least very refreshing to natter about the thing with someone who has a reason for doing so that's better than 'it's a toy' so, thank you for taking the time to explain, it is appreciated :-)
@@Belzediel Hi, thanks for the response. To be clear, using a controller that is produced and tested in the millions would 'likely' be more reliable than using a device you built yourself. However, that would not be the outcome of an FMEA investigation.
If you were to look at this controller in failure mode terms, even though the chance of a particular failure (i.e. jammed button) is quite small, and the chance of it's effect (collision with debris) is smaller, the outcome (Loss of vessel with all souls) would be so great that you would do what many other manned submersibles (and surface vessels) do.
You would have two control systems with redundancy and failsafe changeover. The instant that button jams, you would let go the first controller and pick up the second. You would not wait to change batteries or reprogram a wireless connection because those seconds might be critical.
As an example, here is a quote from an old copy of the DNV rules on redundant propulsion systems: "The bridge propulsion control system shall be independent for each propulsion line; so that any single
failure will only affect one of them, and that operation of the remaining system can continue on the normal
means of operation (e.g. levers). Alternatively a system arranged with redundancy can be accepted if in addition
independent back-up control system for each propulsion system is arranged. The redundant system must be so
arranged that any single failure will not prevent continued normal control of the complete propulsion system.
The independent back-up control system shall be based upon similar input devices as the normal means of
operation (e.g. levers)."
So to answer in brief - there is no mean probability of failure which would be acceptable - only redundancy with separation. Nothing I read about the game controller or any part of this vessel suggested they had the required redundancy - or had done the analysis which would have demonstrated where that redundancy was required. An assumption maybe, but one which I have yet to find evidence to disprove - unfortunately.
Great piece of work. I worked in endurance testing high pressure equipment up to around 3000 Bar. This sub failed at around 400 Bar. The failures at these pressures progress through the structure as shock wave rather similar to an explosive event at around the speed of sound for that material. The stress is already in the carbon fiber and you get a cascade failure as the local support is removed by the failing material. I have no data for the speed of sound in carbon fiber in this configuration and pressure but it will around 3000 meters/sec per second much faster than the speed of sound in water at 1450 meters/sec. This means the tube may well failing faster than the water can keep up with . This would cause a huge mass of water accelerate conically inward ( the open end toward the direction of travel) in the direction of the end that did not fail first. As the in rushing water ( many tons) is at really high speed ( 150 mph +) when it collides in the center it creates an even faster flow towards the remaining end . When this hits the end you get the mother of all water hammer events blowing out the window. The violence of this event is difficult to comprehend. This explains why the window was not with the sub. The blown outward flange was on this end too so I think this could be included in this violent event. The whole thing would look a bit look like the copper in a shaped charge anti tank round going off. All this happened in less four thousandths of a second the victims could not have sensed any of this thank goodness.
The key to Carbon is it fails like glass and it suffers hidden stress failures from repeated deformation . We use it in sailing all the time and it is great stuff , light and strong . When it breaks it does not break a little bit .
their are a few things in this vid that i have slight issues with, seeing the outter flange hanging after the thing has been salvaged from the bottom of the ocean, stuck on a ship and then unloaded at a port, and you see the flange hanging down and assume it got blown outwards? perhaps it got sheerd inwards while attached to the carbon then its weight and the salvage process makes it look now like its hanging outside, doesnt mean it got blown outwards. also something i still dont see anyone mention is the fact that the glue bonding the cylinder to the titanium flange had to not only take the stress of the dissimilar materials incomtatable compression properties each cycle, but the amount of hours they spent with the door hanging open in rough seas troubleshooting the long list of issues, the amount of missions that got scrubbed, each time with the door spending hours open with all that uneven force from that heavy ass door hanging from one side must have been putting serious load and fatuige on the bond that it just wouldnt deal with well like it would all the other loads its subjected to, i truly beleive its that hindge and hemisphere being swung open and kept open far too often that caused the most stress and fatuige on the bonding surface that it just does not look to me like it was designed with that load in mind, yes its got a well engeneered joint structure to put up with the stress of dives, where its all evenly compressed and both hemispheres are basically pressed inwards onto the bond while diving, but its got a sheering, twisting, peeling load put on it from the door
Those flanges look like a good thing to look at further to me. They are quite thin if you consider what the axial forces are doing to the cf tube. Could it be that the cf tube was being compressed to such a degree that there was high load being placed sideways on those flanges? The animation did not show a radius at the bottom of the flange recess so I wonder if there could be some progressive cracking showing up in the flange breaks, note the inner flange was shown to be broken too.
@@dzzzzbutube its very possible, but i think its more probable the forces involved are so insane
i think you are are right, maybe an internal metal skeleton to support the weight of the doors and not put twisting forces on the carbon fiber when they were left open
The flanges and titanium end caps are blown outward, the bolts between them are blown, and the window also. Big explosion (just after implosion) like a diesel.
The flange could be peeled open due to a failure of the CF tube as when it collapsed it would natural bend in the middle but push out at the ends and hence push the flange outward. Also as it failed the end domes would be pushing inward and would also push the flange out when the collapse started. In it self I don't think it was a problem with the flange but the CF and glue used, in my opinion. I await the report but it may never be fully disclosed as it's such a contentious subject already. It is sad when people die but the the correct testing could of saved them and may have improved the design to a point it could be usable tech.
Thank you for this video! It's the only video or article I've seen that actually attempted to show the Titan components, what was on board, what was in the tail cone, etc.
When this happened the first thought that came to mind was the difference in material compression between titanium and carbon composite. Primarily as how it would effect the glue joints and internal/external flanges where the 3 materials come together to form a bond/seal. The other thing is how thin and short the flanges were in comparison to the thickness of the material they were binding...
The splitting (flanges) in & outwards, seems to suggest a force of fragmentation ?
We have repeated pressure cycling of a plastic cylinder glued to metal ends, and repeated temperature cycling of materials with dissimilar thermal expansion coefficients. Then we have compression forces at each end, pushing against the cyclinder ends. Then we have repeated pressure cycling of the plastic cylinder. Just take a look at the other submersibles that are capable of descending to the Titanic, they have thick metal pressure hulls. This was a Primark/Lidl submersible.
Good analysis, another thing to point out here you didn’t mention.
The carbon fiber tube(both models), were constructed in a warehouse, not a hermetic environment free from dust and other airborne particles that could’ve been introduced into the in between layers of the cabon fiber as it was being weaved.
Also Ocean Gate removed a lot of their videos showing these construction processes(likely to hide evidence), and you can actually see air bubbles and imperfections in the layering process of the finished carbon fiber tube.
Also a former engineer told Stockton to make the fiber tube at least 8 inches thick to ensure it was strong enough to withstand the ocean pressure at depth, Stockton went against this and it was only 5 inches thick.
So I think imperfections in the tube hull combined with it not being thick enough as well as the flanges were weakening with each subsequent dive, and maybe water was beginning to ingress into the layers of the carbon fiber or finally penetrated the flanges and the glue and it was just enough to cause the catastrophic implosion. That’s my take on it anyways given what’s available.
I doubt any contamination was significant. Do you think leaves were blowing into the layup?
One basic thing about the whole sub business concept is people subjecting themselves to such an extreme risk just to take cell phone pics through a porthole. It isn't like climbing or scuba diving where you are intimately connected to the journey and process. Here you are just sitting and totally passive and then you glance out a window. There really is not much difference in the end than if they'd had just stayed on the surface and operated a robotic sub and taken pics that way. Maybe they could've done it while being bolted into a cold tube lol
One thing people starting new businesses like this share is an almost blind self-confidence. You really need to be insanely cocky to not be cowed by all of the risk and not scared of failure. Unfortunately this self-confidence bled over into the engineering and safety aspects of the sub.
I couldn’t agree with you more. But as a designer I do admire the design process and trying to turn idea into reality. And I really admire those who with endless dedication and hard-work make reliable and dependable things useful to society. A sub for the uber wealthy to get their dopamine rush does not satisfy my definition of useful to society.
I’m really hoping someone on the inside gives me some new information on this story…. I can’t help being fascinated by it all.
That is kind of like saying going into space is stupid because all you get to do is stare through a window. I think knowing the water around you could kill you in a split second will add to your feelings of being on adventure that you cannot get from a remote view, not to mention the cold, and any other effects you might feel. If you wore a pressure suit, you would just be in a much smaller submarine, really, albeit one that lets you interact more with the environment. Still, what would you do at the titanic? You probably should not touch anything if you want to keep it as a preserved site.
@@itoibo4208 They are entirely different. Going to space was for furthering science and exploration. Going to the Titanic is only for the entertainment of the uber wealthy and to give them bragging rights.
@@itoibo4208Going into space is more than just sightseeing though. You are encased against a hostile environment for a bigger purpose.
Not getting on a sub with Mike, he didn’t learn the lesson about carbon fiber… The carbon fiber used was a fabric but what is holding that fabric rigid? It’s a resin, the only thing holding the layers of fabric together is that resin. Even under tension the resin will break down which is why the Boeing 787’s fuselage has a life cycle of 44,000 pressurized flights. Everyone who previously went on the sub discussed vary loud cracking sounds, which is a clear sign of delamination between the layers of fabric. If the sub had gone down and stayed down, it would probably still be intact. The issue is going down and coming back up, essentially the equivalent of a flight cycle. Each time it compresses and contracts, the cracks are getting bigger, and more frequent. Rush knew this but still neglected to do an x-ray because he knew it would be the end of Ocean gate, why not go out with a bag. Congratulations Rush you made it into history, I’m sure you’ll be in lots of engineering textbooks for decades to come.
Ocean gate casually littering the ocean with every dive makes me heckin frustrated. Thanks for this great video
This sub suffered from multiple systems failures in 80% of its dive attempts, and none of those had anything to do with the CF or game controller, I would love to see a follow up video on these failures
I thought one of them was and they got away with a software update middive
very true -
So the CF hull making loud noises isn't a concern at all? I don't get why you people are trying to defend composite materials when it was very obviously the cause of failure.
because, like airframes -it gets better. Boeing had nasa to help- @@pyropulseIXXI
@@pyropulseIXXI the material could be fine, but you have to remember that designs have trade-offs. This is nore likely a failure caused by some of these design goals, and not the material. Subs all make noises, as far as I know, but a carbon fiber one should probably not be making sounds like a gunshot, at least not after the first dive or two.
What has happened will set the carbon composite science back decades. Now any time someone brings up using them in any safety capacity this will het talked about and not tried. Proper testing is sooooo important.
not sure about that, cf is embedded in industry its a 'niche' product its uses are well known and growing all rush has done is to show that his configuration is one to avoid
I think it's important to remember that airliners (representing a multi-TRILLION dollar business) have only just began implementing composites in the last 20 years (despite the immense weight reduction and thus efficiency it provides.) Composite airline parts are built with ample metal reinforcement and held to an unbelievably narrow tolerance. Airbus gave us a look into how they build the composite-based A350 and the complex, precision engineering required to build those parts is unbelievable. In fact, it is considerably *more* expensive to build with when compared to traditional aluminum airframes. If Boeing has only *just* figured out how to build with composites, it's best for silicon valley techies to leave it the hell alone.
Ah ! finally we have someone who explains what happened. This is exactly what i explained to my friends as i work with carbon fiber since more than 20 years in racing car applications. The big problem come from the end caps, applying 5-6 times the pressure on the tube ends because of geometry, so after a while and many pressure variations the tube end got some wear coming from the resin aging through the process and the fiber becoming slighly wrinkled as you explained. So cracks start to form and one day you have a sudden major failure .
Just looking at the interior photos gives me the creeps. I wouldn't have gotten locked in that thing on dry dock if they paid me $250,000.
I think id have to consider climbing in it at dry dock for Half a Billion , not a penny less, no trick,s lol, oh, the clock starts the moment my last foot leaves the ground, then as soon as the clock strikes 3-minutes, Done, im back out, with my half a Billion in hand, on my way to the airport !! its been real,Fun, nice seeing everyone, gotta go, W/H/W 10/11/23
I...can't help but feel anxiety just imagining sitting inside this thing while they bolt it shut. Fascinating video here, thanks for taking the time to do such a detailed breakdown. ... ugh... my word choice feels...off.
Me either. You'd never get me in that thing.
amazing - yes. but no matter what - always trust in God.
@@prestonburton8504 trust your self...... trust in God is insanity
Yeah, there's a damn good reason why certified submersibles have a hatch on top, openable from both sides.
If something goes wrong, they can open the hatch on the surface, without outside help.
just like our defense subs, right? certified to 300ft (the test depth is classified) they have no openings - neither forward or aft, on on the sides. yep, just looked back. you are right. @@jamesm5787
Great video. I hadn't looked beyond the headlines until I saw this video. I'm glad I found this first.
It would be interesting to see what OceanGate's process was for generating the CF portion of the hull. Seeing videos of the layup process, I was surprised that there wasn't more attention paid to area cleanliness as well as temperature and atmosphere. A documented process review would prove interesting.
documented? we dont need no stinkin documents.
It literally looked lumpy.
Carbon fiber for those who don't know is essentially a rope. Think about the cables that hold some bridges, they are designed in a way that their tensile strength is much higher than their compression strength, the material is so strong that it could sustain strong compressive forces but only at a fraction of what they can support went tensed. Carbon fiber is by its design meant to be extremely impressive when tensed but it can only hold a fraction when compressed. Steel hulls are extremely strong under compression when using basic geometric shapes like a cylinder. To be an innovative application of carbon fiber one would have to understand how to weave it in a certain pattern and calculate a certain geometry for the submersible so that under uniform pressure the carbon fiber would have to extend in order to keep everything in place instead of contracting. This is admitting such a solution even exists. The other option would be to brute force the problem by creating such a thick and dense carbon fiber hull that even if the compression limit is only 10% of the extension limit it would still be enough to easily go back down to 5km and come back up. I am not even going into more technical details such as computer modeling. It is extremely easy to model the behavior of a cylindrical uniform Steel or Titanium hull (so much so that a noob could do it) whereas it is extremely complex to model a material composed of two or more due to the non linearity of the partial differential equations which results in bad behavior of the numerical solutions that your software will generate.
Be careful getting your technical explanation of carbon fibre from James Cameron 😂
It appears carbon fiber maybe useful for submersibles for shallow dives...but not for trips to the TItanic or to the Mariana Trench.
Rope is a wrong analogy as rope is itself made from strands to be flexible in many directions, those are strips. For a better analogy try folding paper more than 7 times over ;-)
So this is why he was supposed to test the design. He could have done a couple of test dives to increasingly deeper depths - say start with a depth to 1km first, then ultrasound the hull and check the structural implications.
If all is OK, he could gradually increase the dive depth, rinse and repeat until there is confidence in achieving the required depth.
That's the least he could have done for passengers. Instead, he was a cavalier cowboy with delusions of grandeur.
😂Yeah that sounds great but unfortunately all the real experts who do submersibles for a living say carbon fiber isn’t suitable for deep submersibles
Axial Compressive strength of carbon fibers is 10-50% of their tensile strength. And transverse compressive strength is 10-20% of axial compressive strength… even without defects
What is your point? Yes, in tension carbon fibre is in a class of its. In compression it surpasses most steels.
You must work in vacuum to manufacture w/o defects. Even then it could be stronger. Titanium would have offered better margin for error.
@@miketan4803Margins for manufacturing tolerances and errors )within margins) should be considered for the primary design. I worked on the C-17 cargo jet. The wing broke prior to it’s theoretical limit during it’s ultimate load test. There was a Defense Science Board called by President Clinton. I got to hear some of the results of the analysis. It was interesting to hear how conservative the designs were. One interesting thing was that the aircraft had twice the number of rivets and other mechanical fasteners than needed. Allowing for some very poor manufacturing margins.
@miketan4803 exactly. With an autoclave. There were so many questionable procedures and lack of controls. Maybe cf could work for subs, but we certainly didn't learn much if anything from Titan in that regard thanks to Stockton's haste. He should have been testing after every stress cycle. X-ray and ultrasound.
@@Mike-Bell the fact that it surpasses most steels is meaningless. Most steel tubes are not fit to withstand such immense pressures. It's not a matter of being better than something, rather, strong enough to do its job...
you started by saying that the media made the carbon fiber hull as a bogie man and then you described how you think the carbon fiber failed.
Wrinkles verse de laminating is really just semantics for the average person. The key is that the hull was untested and went straight to commercial use at extreme depth. Even aircraft with aluminum hulls at 1 atmosphere need to be regularly tested for cracks caused by regular pressurization.
I sometimes have a feeling I live in different reality than most people. There are people even here in this comment section confidently repeating that CF cannot be used for this application. Yet, it has been used 12 times successfully before it failed. The reality clearly proves that it is possible. Now it can be entirely possible also, that the limitations of the CF in terms of economics of it's use in this application are prohibitive, but technically, it clearly is capable of doing it.
I have a sense that one of the reasons why Rush ignored the many warnings he got was exactly that the warnings were in a form of 'obviously you can't use CF' or 'this will never work' which made him discard them completely. The lesson here is that even in criticism you should be precise and accurate and not overstate your case. Your analysis here is good exampe of that approach.
This contained some information I had not seen before. Thanks.
Wow. Actually not a clickbait video like all the others. Thank you.
I wonder, though, is carbon fiber really that strong in compression? I failed to find much about it (maybe because the opposite notion is trending so much). I am not an engineer, but I handled carbon fiber strips and composites, and based on that I would never imagine it being strong under compression. At most it would be good at keeping the epoxy in check and not deforming, but in reality it would be under tension (inward) and just keeping the geometry consistent enough to withstand the pressure. How much weight of the hull was CF and how much was the epoxy bonding? I guess epoxy made the bulk of the real strength, or am I completely wrong? In either case, any delamination (like the endcaps pushing on the end of the carbon fiber strands and pushing them apart) would spell disaster, once you compromise the intended geometry the whole strength is just gone, so hearing any kind of crackling should warrant immediate testing of the hull.
@zviratko Take a look again. I've found several scientific papers with measured compression strength of carbon fiber composites. I've seen values between 20 % and 60 % of the tensile strength and airasj1 has experience higher values in his work. The compression strength is highly dependent of how the specimens are made.
@@fuglbird And that's the issue. Based on what we saw, I'd gather closer to 20% at the joint due to the fibers not being under tension. Add in even from the videos that we did have, obvious bubbles in the epoxy and a fairly dirty environment (definitely not a clean room), certainly not anywhere near the 60% end of the scale.
Metal alloys, on the other hand are almost idiot-proof as you simply order a tube to be made, like they did with the end caps, and are done. Decades of testing already done on the alloys and one factor removed from the design's (rather large) list of worries.
This is the first time I've watched one of your videos. I thought it was really interesting and well produced, avoiding all the speculation and just looking at the bare facts (and even questioning the mighty Real Engineering channel!). Subscribed 👍
Welcome aboard!
Very interesting video. I like your take on this subject.
13:28 Yes titanium and carbon are bonded in aviation, but aviation is not a good analog for deep see usage. Carbon fibre composites compress much more than titanium. The haul would simply shrunk way way more that titanium faring under the deep see pressure. That isn't as big of a problem in aviation, where pressure differences are magnitudes smaller. This was a crucial potential failure point, but there was no proper examination or testing of this bond. Not to mention that they didn't even glue it in a proper clean and temperature controlled environment.
Comparing Titan haul to an airplane wing is also not the best. Those wings are baked under pressure in autoclaves during the drying stage, which reduces the chance of any dry spots, bubbles and other imperfections. They are also thin enough that they can be properly examined (x-rayed) and tested. Nothing like that was done for Titan.
I like your theory about axial fibbers, it's another example of how many corners did they cut and how botched the whole build was.
I agree with your conclusions. Could you build a carbon fiber haul for submarine? Probably, but you need to go above and beyond with research, quality control and testing. Those guys didn't do you it, they were only interested in cutting costs.
This was a well presented discussion regarding the Titan implosion with truly excellent graphics. But the one point of interest that was not mentioned is the elastic modulus of the two materials, carbon fibre hull and titanium end caps. They do not react the same under pressure, so over time there is going to be degradation.
Great point but 90% of my audience doesnt really want technical detail so I am hesistant to give too much detail and bore them.
The good thing about combining Titanium and Composite is their rate of deflection is very similar to the extent that differential movement is usually not a big factor. And surprising to me when explained this by the expert I consulted is composite deflects slightly than titanium and that explains why carbon fiber is rigid and therefore brittle.
I am glad you are interested in the technical details because so am I.
@@Mike-BellI certainly appreciate the detail. Perhaps you can add it as a "foodnote" at the end of the video, so those interested can continue watching while the general audience has an on-the-point first 15 minutes.
Yes more technical details are essential
very good!
This reminds me of the darwinian advancement of early aircraft, when the designers were the test pilots.
The good designers lived to spawn more designs...the bad ones not so much. 😮
haha it would help to be a good pilot, too, and a bit of luck. At least he left some clues for anyone wanting to try this again.
Of course, back then, the science wasn't completely understood. Compare that to 21st century deep-sea submersible design where designers have decades of research and experiments to help guide them.
I have worked with Titanium and Carbon Fabre for yachting purposes. My limited engineering knowledge is asking about differential thermal expansion and contraction... and Youngs Modulus is different for both materials... As you mentioned a rounded filament wound shape similar to SCUBA tanks would have been a better design... or a sphere... BUT then you have holes at the ends for access... and there would likely be a higher resin to fiber ratios due to the geometry in those areas --- plus more sharp radius curves === and possibly some cutting of the fibers for access ports. === and this could be a place of weakness --- it just doesn't take more than a pin hole to start cutting and rupturing materials at those pressures ... or worse yet a catastrophic failure... Look at the water jet cutters --- that could happen down under .... with no way to stop the intrusion.
Excellent overview. Thankyou for explaining to your audience the basic principles involved. I tend to agree with your assessment.
I am a filament winder, and do deep sea and gaseous pressure vessels. We generally burst test to 2.5 times rated pressure and cycle test to 1.25 times rated pressure fill and empty up to 450000 cycles! This takes a long time and lots of power, but helps us sleep at night.
Thanks for putting together this excellent overview with out the sensational hysteria. It must be very time consuming.
This was a very reasonable overview of the craft, with great insights on possible weak points. The craft itself was working astounding 15 times, but as you pointed out - we (and them neither) had a clue, of what the safety margins were , and how much role material fatigue played in the catastrophic accident. That ist really unfortunate, because the idea itself still looks pretty promising - even from a technical standpoint! Thank you for carefully pointing out how a responsible path to such a submersible could look like.
It didnt work well 15 times lmao. The use of the carbon was wrong
The thing had cracks you could hear happening. It was weaking 15 times
@@lukeamato2348 The first Jet airliner type "De Haviland Comet" used riveted Aluminium wrong. It killed around 100 people before the FAA finally revoked the flight permisssion. After that, they did a proper investigation and found out about the extremely rapid fatigue due to the pressurized cabin stress on the metal. They changed little things on the manufacturing process on that type (and the window shape, but that wasn't the origin of the cracks), and used several new built ones for the UK military as survey planes up to 2011. So while the manufacturing had catastrophic flaws, the overall idea and construction of the plane type was fine. Alas, Passengers would have refused to use it due to its record and it had gotten too small anyways, compared to the competition. So it never went back into passenger service on scale.
This video shows the possibility of similar causes for another new material and manufacturing process, that could have led to the catastrophy. Maybe it could easily have been avoided - but we know too little if that was the cause. Concluding by what we know so far, that this idea of high pressure vessel construction is completely wrong from a material scinece standpoint, seems a bit premature and amateurish to me.
They had to rebuild it. One worked 6 times, the other 7, well 6.
It doesn't look promising at all; homogenous materials can undergo tens of thousands of stress/no-stress cycles
This is the best TH-cam video on the Titan. No drama, just pure facts and very detailed as well. 10/10
I just want to add more on the “Real time monitoring system”
Assuming the leaked transcript is real… The system actually seems to work as intended. It first sounded alarm at [09:28:16] and the last message from Titan wasn’t until [09:46:37]
So that would’ve give them about 20 minutes or more to react… which should be more than enough to initiate emergency ascend procedure.
but then 2 minutes after the alarm sounded, a message from Titan reads “no change with thrust the *rate of descent is increasing* At 35. Going to release the ballast now.”
The only logical explanation I can think of is that the Titan had somehow, gained some weight… which strongly suggests that the water was leaking inside the hull between layers of the carbon fibre. So the process in which the hull failed does not seem to be immediate but took place over 20 minutes until it gave up and imploded.
If not that, then Titan was most likely attacked by a giant squid which cling on to the hull (activating the alarm and increasing the rate of descent) and after 20 minutes of tentacle handling… finally crushed the hull into pieces.
Again, this is based on if the leaked transcript is real. So far, I can’t proved that it is real, but I also can’t proved that it isn’t either. Note that the content of the leaked transcript all seems to check out with the available evidence. Also, both the authorities and Ocean Gate have not come out to denied the leaked transcript either… so most likely it is legit.
Lol giant squid? What drugs are you on pal? Then you conveniently say you can't prove if your theory is right or wrong. Oceangate is keeping their mouth shut as they should while this investigation plays out. It does them no justice to entertain that stupid TikTok video and make a statement about it.
"most likely attacked by giant squid" lmao the Internet never ceases to amaze me
@@zachstoltenburg5150 I know it’s funny right… even funnier when you realised that it is actually an entirely plausible scenario given how little we know about these deep sea creature. Only 2 videos of these creature in its natural habitat had ever been recorded.
One thing we know is that it does attacked whale and shark… basically about the same size as Titan submersible.
"giant squid" lmao
@@moonasha Unlikely but still entirely possible though 🤷🏻♂️
Also worth noting that Giant Squid has been confirmed to be an aggressive hunter. So it will proactively hunt down and aggressively attack whatever it is preying upon.
It might be worth noting as potential risk going forward and avoid designing a submersible in the shape of a sperm whale…
I'm glad you stated that the transcript is most likely fake. For starters, it does not seem to be plausible to me that the dive would have continued with the abnormal descent rate the transcript implies.
Thank you to the video creator for your insights. I'm an engineering contractor for some military in some part of the world. The problem here was too little testing on too radical of a design with too many lives at risk, and most importantly, naive patrons of the business who were too willing to risk their lives.This is more of an ENGINEERING MANAGEMENT problem than an engineering problem. There is a difference
This is probably the best presentation on what happened. Someone soon may be able to use carbon fiber installed to withstand pressure. It'll require better testing to insure safety over multiple dives.
Correct. It is only with proper research and testing do we find better ways to explore this planet and beyond.
Really? It didn’t even get the date right in the description. It wasn’t June 8th. It was June 18th.
If he got that wrong, what else did he get wrong?
Fool me once, shame on you…
Yes, a good presentation but he presents a problematic justification of carbon composite. In the real world where cost of development can astronomical for this kind of material application AND the improbability that such structure could be manufactured without imbedding a lethal flaw AND the fear an educated potential customer would have…this is a nonstarter choice of material.
Great advatages, impractical use.
I understand the carbon fiber shell was designed to be 7 inches, not 5 as built.
@@oldmech619 Even then its problem was it was gradually being destroyed every time it went down there because after high compression, carbon fibre doesn't recover, it stays permanently damaged, although only in a small way. You've heard people talking about the loud cracking noises, that's delamination and individual fibres splitting and resin cracking. The sub gets weaker with each use.
You don't get that issue with Titanium. It can be modelled on a computer to accurately know how many dives at that depth it will take while staying in spec.
The only reason Rush went with CF was to save weight and squeeze more paying customers through the door.
There is no reason why the global submersible world would choose to dump Titanium for CF because A Titanium is well understood and easily modelled in computers to predict strength which you can't do well with CF and B, they don't need to run it as a bus, cramming loads of people in to turn a profit.
CF might be an idea for small subs that could be used on coral reefs, but the bottom of the ocean? Nah.
Your videos are always awesome. It was reported that the US Coast Guard has recovered the aft titanium dome and other parts of Titan, not previously recovered at the time of the incident.
@cameltrophy3 Yes, the reports on the recovery of the aft pressure dome came out just after I posted my video. It's a pity I couldn't include that in my video.
Interesting perspective! I've seen thunderf00t's take on the subject both are compatible as far as I understand. According to him the main culprit is the difference in compressibility between the joint (titanium ring) and the carbon fiber tube.
Oceangate Submersible Titan Implosion Analysis June 30, 2023 Jack Noble
Composite barrel information from internet: 55.9 inch inside diameter; 95 inch length; 5 inch wall thickness; 0/90 CFRP laminate.
With a CFRP modulus of 8 million psi in the 90 degree direction and because the stabilizing effect of the end rings is about 10 times the thickness away from the center, the failure mode will be buckling in the middle of the barrel. The stability formula in Roark & Young yields a failure pressure of 8900 psi. Dividing by the design pressure of 5700 psi give a factor of safety of 1.56. This gives a strain level of .0044 in the composite and a radial deflection of the barrel of .145 inches.
At the ends of the barrel, although insufficient information on the rings is available to determine elastic properties, it appears safe to say that the radial deflection of the rings due to pressure will be much less than the barrel. This means that the rings will be holding the barrel out at the ends, flaring the barrel like a cooling tower and creating significant bending stresses in the barrel and where you have bending, you have interlaminar shear, the achilles heel of composite laminates. Metals typically have allowable shear stresses of over 50% of the allowable axial stresses while composite laminates have interlaminar shear stress allowables of 2% to 3% of the axial stress allowables. If only 1.5% of the pressure load on the barrel was transferred to the rings the shear stresses would be enough to cause delamination in the center of the thickness of the layup all the way around which would account for the noises heard on initial dives but would not be visible and would not cause failure because the critical stability section is at the middle of the barrel.
On subsequent dives this delamination would progress toward the middle of the barrel creating smaller noises, also reported. This delamination is converting the 5 inch thick composite barrel into two concentric barrels 2.5 inches thick. The critical buckling pressure of two concentric barrels 2.5 inches thick is only 25% of the critical buckling pressure of one barrel 5 inches thick so the margin of safety would be gone long before the delamination reached the middle.
Since there is only one design condition of overall pressure it may have been possible to tune the stiffness of the titanium ring to more closely match the deflection of the composite barrel and avoid this problem but the fact that the composite shear allowable was less than the applied pressure would almost certainly lead to the initiation of delamination somewhere on the barrel. The only protection from this delamination would be to install several hundred 5 inch long bolts through the shell and the potential for leaks would render that fix impractical.
It appears that it is probably not possible to successfully use this material in this application.
My theory: Tiny air bubbles at atmospheric pressure that were inadvertently included in the carbon fiber imploded one-by-one under extreme pressure. First the bubbles near the outer surface imploded, which weakened the outer surface, then deeper air bubbles imploded, until the carbon fiber still l@@ked like carbon fiber, but it was broken up around imploded air bubbles on a microscopic scale until it was unable to carry the load. Has anyone looked at THIS possibility?!
Yes, that is how pressurised delamination works, each micro bubble that is compressed, provides more microscopic room for fibre movement to occur at that point, with a change in pressure changing irrespective of if it is an increase or a lessening.
Then it is a question of time and when, not if; once enough fractures between the individual fibres and the resin matrix to fall below the structural threshold for a given pressure, force or other loading being upon the the resin and or the fibres.
.......it will then fail instantly.
This is nonsensical; it is a fiber and doesn't do well under compressive forces. It survived 12 or so dives before catastrophically failing. And bubbles wouldn't implode if they are in a carbon fiber resin matrix; this makes no sense, as what is putting all the pressure to implode it; if it is air, it would just compress; the carbon fiber is under pressure from the water, and the bubbles aren't under pressure from the carbon fiber; but the bubble gap means the carbon fiber has less 'support,' thus the carbon fiber implodes, not the bubbles. Again, if the air bubbles do 'implode,' it is a consequence of the carbon fiber hull failing and not the cause of the hull failing (at least not directly).
It failed because water isn't perfectly incompressible, and it elastically rebounded upon the carbon fiber once the carbon fiber shattered, thus causing devastation.
@@razor1uk610 This is wrong; even if you have no bubbles at all, the carbon fiber would still fail; it has micro-fractures and cracks, which has nothing to do with bubbles causing this; the bubbles, if anything, are a consequence of this failure
Further to that, CF undergoes an extremely unique form of delamination called Snap Buckling. It's been found occuring on underwater cables. A very terrifying form of delamination when the inner most layer of CF is actually the first to go setting it an instant chain reaction.
possible! it withstood multiple dives -
As an engineer and once scuba diver, I’ve always had issue with MSM assumptions about this loss. Starting with nonstop criticism of wireless game controllers. Any and all propulsion controllers need robust design and redundancy, no matter the specifics of their design. These controllers may have been perfect for the application. MSM automatically demonized this. As for carbon, its simply not just the material. Its was likely the lack of truly thorough testing and finite element analysis, destructive testing, ultrasound and independent third party testing and review. Not simply the “carbon”.
Yes. and I also wonder why all the hate on the controller. It worked fine? needs no wires through the hull. seems like a good idea.
@@itoibo4208plus, a reliable technology that has been in use for decades
Only the most shallow media focused on the game controller. Most tried to refute the mania and focus on the depth rating (or lack thereof) of the CF and viewport.
I appreciate the tone of this video and was delighted not once to hear the word “hubris”. We all know the Stockton Rush was impatient and too shortcuts. He ignored experts advice. But not all on board with him we’re innocent victims, as Nagolet knew all the shortcomings and had told in a text or email he would rather die instantly and catastrophically beneath the sea than a bored old man (or something to that effect)
There was the usual media frenzy crazy speculation from incomplete information and scathing character assassination…when Rush was not all bad. He had started out in submersibles using his to take research crews and journalist. He had student educational programs. He actually was doing a service. But he became ambitious beyond his financial means and skipped the critical testing to failure and non/invasive periodic testing of the hull’s integrity with ultrasound as recommended-instead relying on Wile E. Coyote methodology acoustic sensors (seriously I imagine them arriving in an Acme box). Some experts have also mentioned a curing process (I am not an engineer) to strengthen the adhesive bond between the fibers.
I kept pointing out your factual errors in that Rush made a second hull after the first one was making noises, and other things, but those minor error are corrected here. Rush went around certification, called passengers mission specialists, outright lied,etc but a complete villain? No.
I even had to correct someone from calling him a psychopath. Really?
The flange torn off the end cap says it all for me. The ends of the CF tube were only stopped from deforming under the compression of the endcaps by the flange which was not strong enough to resist the force of the ends of the tube pushing outward against it as they tried to deform under the compression. Once the flange went, there was nothing keeping the ends of the tube from deforming and squirting out around the sides of the endcap, at which point the pressure simply forced the endcap down the tube much like a mandril gets forced down a pipe to stretch it out.
In a sense, the CF tube was being crushed on the ends by a hydraulic press. Forces Stockton likely never took into account in his designs.
Appreciate the time and effort put into this presentation! The gradual, patient, and detailed layout of the discussion, with the intricate graphics and comprehensive editing, truly allows for better insight into the whole process behind the making of the Titan submersible.
I'm glad it was helpful!
9:27 While there might be some compressive forces on the wing, they’re minimal compared to the predominant tension forces depicted in that clip of wing flex. Thanks for the video.
The compressive and tensile forces must balance. They are equal.
As a guy who worked a lot around advanced composites on [military] aircraft, and also the ones used on sports car in my spare time, all I can say it that CFRP is light and strong, but it gives almost no warning when it has to give... Just look at F1 cars when they hit something, and you'll have the whole view of what happens when CFRP fails : it shatters like a little grenade ! Thousands of sharp little black carbon blades spinning in all directions. And to add to the injury, CFRP is not good at withstanding compressive loads. I mean way less than what it is able to do in terms of tensile strength.
That's why many helium/nitrogen/oxygen/"gaseous whatever you want" high pressure tanks are made of composites in aviation and rockets and work very well. That's also why nobody ever decided to build a fiber-reinforced plastic submarine before. If composites were good for submarines, the military subs would have done it a long time ago.
- Pressure trying to escape from inside = yes
- Pressure trying to crush from outside = big no
15:14 This is what I've been saying for so long; the excursion price was too LOW! It was so low that I now describe it as predatory. I say this because it put the Titanic excursion within the range of affordability to diehard fans (people who have wanted to see the Titanic up close their entire lives) who could now actually afford to re-mortgage their house to get on board the sub, and some of them did just that. I think these were the people that Stockton Rush was actually aiming at.
Now even if there really is something to this whole "carbon fibre submersible" idea, it's become a poison chalice that no investors will touch for years to come. Thanks a lot Stockton Rush!
I really appreciate the thoughtful, rational way you explained this. I'm so sick of armchair experts who have no experience whatsoever in the design and construction of such a unique vessel. SR obviously made some literally fatal mistakes in how he treated risk and testing, but there's no reason that some company/institution couldn't spend the time and money to properly test and overspec such a craft successfully. He really was blind to the risks, or at least chose to ignore enormous issues with the whole design and build process, skimping on testing and lacking a willingness to seek outside expert advice and admit he needed such help. It would be amazing to see someone do it right and open up more of the ocean's depths and mysteries to people who ordinarily would have as much chance of experiencing such environments as the average person would to stepping foot on the moon.
But many "airmchair experts" are experts. And all strength formulas depends on there being zero delamination. Because a normal rope is enough to show delamination isn't an issue for tensile strength. But a huge issue for compressive strength. And no one has yet shown *existing* manufacturing able to properly solving the delamination issues for this usage case.
Which makes lots of "armchair experts" correct. It's irrelevant what the theoretical compressive strength is, when you can't actually build a hull to that level.
Reality being the Man built an Amusement park ride. No more.. No less
Cost cutting was endemic.
and add to that the problems of the cf/metal joint it is possible to design and build a better joint at greater cost, but there comes a point were the fatigue life deems the hull unsafe in any event and you have to make another, is the cost of making replacements in c/f cheaper or more expensive then an all titanium or steel hull in the first place@@perwestermark8920
The author of this video is an aerospace engineer, not a naval engineer. AEs do work on submarine design but that's no reason alone to take his statements on authority.
The hull was basically 5 inches of epoxy resin. I give the CF little value in such an extreme compression application.
Middle of the hull would deflect and work more than the ends, since it had no internal bracing. Popping sounds were probably CF filaments sporadically failing. Obviously...any tiny defects would grow each dive cycle.
I'm just a guy who is curious about science and I found this was fascinating, thank you for putting it together. As usual, the media just ran with whatever got the the most views, damn the science or facts.
The way they glued the titanium rings to the CF alone, absolutely ridiculous. They rolled the glue onto both parts, set the ring on top of the tube, done.
No elaborate resin infusion technique or so to prevent voids in the glue, no vacuum bagging afterward, no autoclave curing. Nothing.
They built pressure vessels like it was an Arts'n Crafts project for their Etsy shop or something.
And then there's the combination of CF and titanium. I'd have to look up the exact numbers, but I'm pretty sure titanium has at least twice the the temperature expansion rate of carbon. They glued that hull together during summer judging from their clothes and sweaty foreheads, then repeatedly sent it down to the bottom of the ocean where it's 0°C. The internal sheer stresses in those halfassed glue joints must've been substantial.
This is by far the best 3D model of the Titan. Thank you for sharing!
Glad you think so!! 🫡
Its comical that he installed acoustic sensors and relied on those to detect problems, but paid absolutely no attention to the "gunshot like noises" during every dive.
People who have been on big subs talk about the disturbing sounds they make when diving to depths. I am sure he thought about it, and might have even expected it, but figured it was "normal", especially after a few successful dives.
@@itoibo4208 This was a 3 piece structure barely big enough to fit 5 people inside. Not a sub hundreds of feet long big enough for over one hundred crewmembers. Subs designed to do what this guy wanted to do don't make "shotgun sounds" without positively identifying the source prior to the next dive. To ignore those signs is literally asking for what happened to happen.
Great video, nice to see someone who actually understands the issue rather than just blaming composite material. One correction I think I have is the distribution of forces, you've stated as 3/4 in hoop and 1/4 axial. I thought the distribution was 2/3 in hoop and 1/3 in axial, although this is based on my knowledge of pressure vessels with internal pressure, i assume the same is true here just in a different direction. This is a based upon stress in hoop being pr/t and pr/2t in axial, i.e. giving a 2:1 distribution ratio.
10:49 No it doesn't. The composite is not isotropic, or even orthotropic, it's anisotropic, with maximum stiffness and strength aligned with the axial direction of the fibre and in tension only. This means the hoop arrangement of fibres carry axial forces only, i.e. internal pressure causes the fibres to be in hoop stress - this how this sort of composite is meant to be used. In compression the matrix material carries the force and fibre does nothing (you can't push a rope analogy). My PhD was in numerical modelling of crack propagation in long fibre metal matrix composites (MMC's) - titanium matrix/carbon fibre reinforcement, or aluminium matrix/carbon fibre reinforcement - which run in the hoop direction which is essentially what this composite was so I'm familiar with MMC failure modes. The upshot is, the designer of this vessel did not understand the stiffness properties of the composite he was using and paid for this with his and other's life. 11:20 Yes, exactly, and this is how it failed in hoop as well; remember the fibre is there to carry an axial load _in tension_ it cannot carry a compressive load; you can't push a rope.
By far the best explanation of what really happened. Thank you for taking the time and patience to put it all together.
Thanks 😊
Agreed, excellent video. Balanced view.
So there are many comments here and some half truths and statements from people who sound like experts, but the stuff they say is just wrong. So being an Engineer that worked for the past 30 years in the aircraft industry and design and build high performance sailplanes from exclusively carbon fiber, I will add my 5 cents.
1. Carbon fiber is a fantastic material with some limitations. The compressive strength is lower than the tensile strength and for carbon roving my own measurement over a 20 year period in our University Materials Lab, I found the following. Compressive strength 670 MPa, tensile strength 1000MPa.
2. In compression the fiber absolutely gives the strength. The lower value is due to the fibers not being absolutely straight and therefore they buckle (Engineering term for structural instability of a column in compression) on a micro level. The resin only keep the fibers straight and contribute very little to the compressive strength as the resin strength is only about 70 MPa.
3. Somebody commented that the analogy of a wing is not correct as there is not really compressive loading in a wing. That is absolutely wrong. The structural element in a wing is basically a beam that resists the bending moments. In a beam the one side (bottom for aircraft) is always in tension and the other side in compression. We use carbon fiber primarily as the structural element in our beams and the upper flanges is stressed in compression. Because the compressive strength is well known, we can design save wing beams. As a matter of fact, the tensile strength is an useless property in this application and we are only interested in the compressive strength.
4. So to say CF cannot be used in compression is really an idiotic statement as it is untrue. The compressive strength is merely lower than the tensile, but still very high and usable. If you know the value accurately you can design safely with it.
5. The application of CF is a submersible is not necessarily wrong. 30 year ago nobody used CF in aircraft. Now it is well understood and used (787). At some stage somebody must push the limit and use this wonderful material in new applications like a submersible. The problem is that the problem must be well understood and the material be properly used. The compressive strength of CF makes it a good candidate for this application. The manufacturing method used was probably not completely suited for the loading of this design. My own analysis show a SF just above 1 for the limit loads. This is too close for comfort and a little more structure might have been the right thing to do.
6. I Agree with the comments that the fibre must protected against water ingress that will cause delamination.
Regards
Attie
Thanks Attie. I have pinned your comment. I hope your expert input moves the discussion away from engineering according to celebrity and toward scientific engineering 😁
Ok helpful feedback on kpas!
Re "the stuff they say is just wrong"
My thought on this comment is that engineers say incorrect things all the time too, only a few of us are very careful and it's not necessarily a professional advantage.
JBP says talking is thinking, and I think this is a good venue for anyone who's interested. It isn't necessary to discourage discussion, correct or otherwise. I also think it's valuable for people to practice discerning what's correct from what isn't. Just my 6 cents :)
When you state that "CF cannot be used in compression is an idiotic statement and that CF in a submersible is not necessarily wrong", are you implying that the Titan's CF hull is intact and may be located and brought to the surface? What does all of those sharp cracking noises that they heard on the first dives tell you. Would you volunteer to descend in a CF hulled submersible to the Titanic? Any time someone starts laying out their credentials in a discussion I tend to suspect their argument isn't going to be a strong one.
@@denniscliff2071 for example a thin skin of metal around the CF may have prevented degradation from multiple dives, there are many potential solutions... the problem was that SR didn't even test one solution before embarking passengers. Probably our military has test data they aren't sharing with the public, that could help inform a project like this.
@@denniscliff2071Not at all.
He said that with his calculations, the hull was not designed to be strong enough. A safety factor of close to 1 is far too low for a human carrying pressure vessel. No one is doubting that the CF hoop failed.
Well done! I worked 33 years in the carbon fibre industry and I was wondering how the fibres were aligned in the cylinder. For a number of years I was part of a team that worked on very thick carbon laminate structures and worked out a way of curing them under pressure without wrinkling or deforming the laminate. This can be very difficult to do, but can be achieved. The combination of filament, winding, and hand layup would have been difficult to accomplish and very may have been the source of the problem.
He said the second tube was laid up longitudenly with a robot, and even had a picture of it working.
@rise_above The are unconfirmed suggestions that CF tube was built up in 5 one inch thick increments and cured between each layer. Was the very thick build up you worked on done is a single cure or multiple? More on the layers with a foto showing the 5 distinct layers in this video th-cam.com/video/Wg4L64uXvnw/w-d-xo.htmlsi=0lw3JgHIiDHJMbOj&t=518
Our design was for an engine strut support, thickness was around 3 inches and it was done in 3 cures. We patented a process to cure the part in a way that allowed us to control where and how the wrinkles are formed. When curing thick laminates under pressure and high temperatures your going to have wrinkles forming, the trick is to control them. Then fill in the wrinkles before applying the next layers.
@@Mike-Belldid they use a autoclave?
I still find the statement James Cameron made at the time of the accident is still the best description of what happened. I understood Cameron to say that carbon fiber wears more quickly under compression than metal, and metal doesn't last forever under such force.
Fantastic video! This is the most comprehensive and detailed description and model of how the submersible was constructed that I've seen so far. Also, this is the first time I've seen that video clip of the carbon fiber being laid axially.
Yes, it's one of the most informative videos on the subject, and many of the comments are better too.
The best information about the overall design of the submersible I found so far, thank you. One of the most important points: it has confirmed my suspicion the sub wasn't using variable buoyancy system, and its buoyancy has been solely controlled by solid balast. One of the unique (not necessarily bad) features of the contraption.
I would prefer using a pump and water for ballast, but I have to say I am impressed that the crew could, if all power failed, just lean the craft over by all going to one side, and causing the ballast to dump out.
@@itoibo4208 lets assume you want to change boyancy by 100kg for going back to the surface, youd have to push 100l of water volume against 500 atmospheres of outside pressure, thats 5 megajoules of energy, 1400Wh, thats a huge battery pack to do this a single time. If you want to periodically go up and down for navigating it needs a hell of a pump as well, lets say you need to change 100N in 5s (like accelerating some thruster) thats pushing out 10kg of water in 5s which turns out to be 100kW of power.
@@NIOC630i prefer something dynamic but I see your point. That would take a lot of power.
the submarine that went all the way down to challenger deep used the same thing
@curiouscat8457 Yes routine bouyancy control was with solid ballast only. For emergency they had a high pressure air tank that would inflate a bladder for fast surfacing but I havent read anywhere that they used it or tested it. There was a pump system inside for the crew to operate to open the air tank.
Regardless of materials, Mfr. practices, assembly quality & the necessary testing/validation; the biggest fault of the project was the narcissism & arrogance of Rush. Mr. Bell, you've made a wonderful Engineering video & I hope everything needed is done to further this type of construction & the usefulness of CF.
When i was a kid a bunch of us drew up plans to convert a 500 gallon propane tand to a sub and charge the other kids to take them down in it. The plans disappeared over the years. Now i know who took them.
The dome to cylinder joint is quite different from that of all the wound cylinders that are routinely used. The design normally has smaller metalic bosses in each end that are included in the spiral winding process, producing a much better cylinder-barrel structural interface. One has to watch for thermal effects too, where the titanium dome will want to distort differently than the carbon barrel at depth were the water is quite cold -- again a joint issue
Finally someone is mentioning the joints! The interface between the composite and metallic is ALWAYS the weak point of all composite designs (regardless of in tension or compression or shear). Amazing amount of misinformation out there on material strengths (look at the composite laminate strengths in tension or compression not the fibers by themselves...and if you don't understand that you really are not qualified to have an opinion). With respect to the author's concern about the fiber laying in the axial direction that's the exact same process used to make those airbus wing skins you showed (typically tension on the bottom and compression on the bottom under in-flight loads) so I think that's not a concern. Making a 5" laminate this way with less than 2% voids, and without any QC verification or certification plan that would be a big concern also. But over all this video was one of the best I've seen (Just a retired aerospace composites engineer so what would I know?)
@@lorenhendrickson2843any idea why they used metallic end caps instead of laminate ones?
I am not a composites engineer (but work with a lot in aerospace). This joint is what concerned many. Temperature change co-efficient s, adhesive retaining it’s strength, etc.
Much more difficult to fabricate the end domes out of composite, and then still have to have metallic flanges to attach to the barrel so makes sense to make an integral dome and flange...just haven't seen and engineering detail of what the flange to composite bond joint looks like
@@lorenhendrickson2843 I’d settle for the extra weight and the simpler risk profile.
Great video, give props to the 3d animators.
Thanks. The animators would be me. That’s why I take long to get my videos out. Would love to employ assistants but need more subscribers before I can do that 😅
@@Mike-Bell at 7:29 the video states that 20mm = 3.25 inches. This is incorrect.
@@BobBob-nr1zt well spotted. 20mm
3/4”
I’m not very familiar writing in imperial 😅
I always enjoy a technical video that uses animated graphics to explain/show construction and operation. It makes it so much easier to understand. The graphical simulations used in this video were excellent.
One issue with carbon fiber is the amount of shrinkage due to compression it undergoes at depth, and that leads to significant loss of buoyancy. Metals such as titanium do compress at depth, but they don't suffer from anywhere near as much compression as carbon fiber.
I'm pretty confident the material itself is not buoyant, maybe you can elaborate on what you're thinking...
@@jeebusk Sure. The buoyancy of the submersible is its total weight vs the total amount of water that it displaces. When the carbon fiber tube reduces in size due to high compression at depth, then the total amount of water displaced is reduced by the shrinkage volume, thus making the craft less buoyant. By my calculations the carbon fiber would have been compressed by as much as an inch all around, with somewhat greater compression towards the middle of the cylinder. Perhaps the stresses of multiple previous dives allowed the carbon fiber cylinder to compress even more in its last dive. The amount of buoyancy lost could be 100kg or more.
@@paulcarter7445 I'm interested in your calculations, the author has mentioned in comments that he expects them to compress at about an equal rate.
Personally I would actually expect the composite resin to be more brittle, but that may depend on specific material chemistry.
In the video he mentioned the composite thickness but I didn't hear anyone mention the thickness of the domes, which I would expect from anyone doing maths.
@@paulcarter7445 and if the titanium end bell compresses at a different rate than the tube does (and taking into effect the water temperature) then the end bell joint against the CF tube will be subject to immense shear (sliding) forces. If the difference is, say, 1% than that may be enough. The construction video shows that they used an epoxy adhesive under open warehouse conditions to glue the parts together.
@@paulcarter7445. Isn’t buoyancy also something to do with how much air is contained inside the thing you are submersing?
I actually thought this was going to be one more of the videos I've seen about the topic with the same information, but I was really surprised to see how much more detailed and scientificly explained the whole incident was. I subscribed in the first minutes.
Thanks. More to come!!
Yes, it's a very well done video.
Very interesting video - makes sense (actually I have been thinking about the tube design; the thickness of the tube would mean that it would actually be under tension if it was being compressed (at least part of the tube) due to the 5 inch thickness. The longitudonal pressure (the 25%) was unopposed;
This has parallels to the De Havilland Comet; hopefully similar testing is done to figure out what happened. A better design could have been a ‘thin’ (1 inch?) titanium tube, wrapped in 5 inches of carbon fibre, maybe with some external longitudonal braces also.
But destructive testing should have been done.
Thank you for your balanced report that clarified the design issues with Oceangate. I now have a better understanding of the implosion and look forward to the final report.
Hands down the most professional presentation on Titans failure I’ve seen. Very well done sir
Wow, thanks!
It does seem likely that the sub imploded due to poor lay up and design flaws. I was thinking of another possibility is the glue joints that are under extreme tearing stresses due to the different rates of compression and expansion of the carbon fiber and the end caps. In the photos for the salvage, someone pointed out that the end caps were stripped of all its glue.
In aviation composite and composite are glued together routinely. The 2 materials have very similar rates of deflection under load so differential movement which is a great benefit. And suprisingly it is Titanium that has a more give than carbon fibre because carbon is such a rigid material... which is also why it is so brittle.
I have not seen all the photos of the wreck. The photos I did see the end caps were glue free. It seems to me that there should be glue left in the cap ends with bits and pieces of fiber hanging from them, not clean and glue free. Which leads me to believe the glue favored the carbon fiber over the titanium, which makes me think the glue joint gave away before the carbon fiber did?
@@williambattermann5008 While I am not certain, I believe that at any appreciable depth, the glue would be irrelevant. The pressure on the ends caps and the resulting friction should provide far more attachment than the glue could ever manage. The glue may have favored the carbon fiber, but had the glue failed entirely, I expect it wouldn't have been noticed until the sub was removed from the water.
No material is perfect. Even titanium is susceptible to metal fatigue and would need to be retired after load cycling. The problem is they didn't do any destructive testing to see how many times the craft can be cycled. They should have loaded and unloaded the craft until it failed and then do an autopsy on the wreckage. But obviously they were strapped for cash. Thats the real tragedy.
@@Goodgu3963 The titanium rings cups the carbon fiber rather than just being flat. You could not inspect the glue after it has been attached.
Anyone else's jaw drop at the fact that the CO2 scrubber was literally a rubbermaid tub with a pc fan duct taped to it?
It underlines how homemade the entire sub was. A crew member contacted me and let me know that later they used a commercial scrubber. I made a video explaining this with other information they provided th-cam.com/video/i0P56usXhcI/w-d-xo.html
Unfortunately, it got its destructive test when people were onboard.
If you have a look at the recovered debris, the mounting ring for the viewport is hydroscrubbed flush (very clearly seen at 12:20), i cant imagine that flow coming from anything but the collapse of the viewport, blowing out couldnt do it. It would also be one of the few things they would see deform over time before failure.
It was polycarbonate, rather than acrylic, from what i could gather.
The flanges would have been blown OUT by the water hammer (rather than in by implosion). It would also very much explain the remains found in the aft bell.
The imagery of the wreckage is too fuzzy to make any good conclusions. The viewport retainer ring is gone and to me the surface just looks like the ring is missing.
the bolts are missing too, @@Mike-Bell, no sign of bolt holes, and the images on some of the sites were plenty good enough to see it was scrubbed flat
The polycarbonate thing - i am expressing my presumption - i found rush saying it was both at different times, but most of the reliable sources also said PC.