Titan Sub | carbon fiber - Detailed Tour

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")

Music:
Sound effects:
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

[shawnhoem]

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.

[fridaycaliforniaa]

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 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

[tjw]

The primary problem with Titan was the temperament of it's creator. Too many corners cut for limited success.

[TheOneWhoMightBe]

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.

[carbonking]

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.

[protator]

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.

[wazzaracer]

Ive worked with Carbon fiber based competition race 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 is needed.

[bt-]

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!

[Herzankerkreuz]

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.

[captainwin]

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.

[SpaTZz]

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.

[Vincerama]

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.

[grahamfoulkes]

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.

[GrahamHomes]

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.

[mah]

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.

[anninaut]

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. 👯

[The.Spicy.Raccoon]

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.

[TheRealRobG]

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.

[machendave]

He did not want ultrasound testing on the hull.

[seanpeacock]

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.