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Carbon fiber is a great material for certain things like skis and bike frames. A submersible vehicle just isn't one application where carbon fiber is useful. The reason is the material micro fractures under stress. Sure, it's extremely strong. It's also very brittle. Every time it's put under extreme pressure, it flexes and creates new micro fractures. For skis and bike frames, this only becomes a problem after many years of use. Then the integrity starts to fail gradually.

In the case of the submersible, the failure will suddenly occur with no warning.

Carbon fiber is a great material for certain things like skis and bike frames. A submersible vehicle just isn't one application where carbon fiber is useful. The reason is the material micro fractures under stress. Sure, it's extremely strong. It's also very brittle. Every time it's put under extreme pressure, it flexes and creates new micro fractures. For skis and bike frames, this only becomes a problem after many years of use. Then the integrity starts to fail gradually. In the case of the submersible, the failure will suddenly occur with no warning.

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[–] • 4 pts

It just reinforces the CEO's utter disdain for safety and his neurotic fetish for taking the cheaper options - with everything in the build - hell he couldnt be assed doing the CF in a sealed controlled environment and vent it to prevent contamination and bubbling in the layers etc asd others have previously mentioned. His 'new for purpose' acoustic detection apparatus was a complete joke , its just peachy to know your hull is stressed and at catastrophic failure and now you have a 2 hr ascent to manage. Lmao -fcking tards - all of them

[–] • 6 pts

It was all to save a few bucks here and there. He literally jewed himself to death.

[–] • 0 pt

No way were they going to control the ascent. Their plan was to shed weight.

[–] • 1 pt

Oh yeah totally, i meant in that - if the ascent is 2 hrs back to the surface from 13000ft, and even if his fancy pants acoustic dinger chimed beforehand - that is a long time to hope and pray you reach the top with a 'critical infrastructure collapse impending'. Not sure how much that ascent process is sped up with all possible weight shed tho .

[–] • 3 pts

For a negative pressure vessel, it was for all practical purposes made from epoxy resin (with carbon fiber inclusions). Carbon fiber has very high tensile strength. But its compressive strength is similar to string or wet noodles, effectively zero. A negative pressure vessel experiences only compressive forces. So, the hull strength was determined by the integrity of the epoxy resin which bonded the carbon fiber strands together. It would probably have been stronger if they had just used epoxy (as the carbon fiber would just create sharp angles within the resin from which stress cracks can originate), although they would need to control the curing process very closely to ensure that the middle cured properly and that curing was uniform throughout, without cracking or air pockets.

The stresses on the cylindrical section of the submarine would be twofold. Firstly, the water pressure acting perpendicular to the surface of the cylinder, trying to crush it inwards. Secondly, a longitudinal stress from the net forces acting on the two end caps. Based on the hemispherical design of the end caps, and the titanium mounting rings, this would create large forces pushing directly down the length of the cylinder. Any small deviation, flaw or fault in the material could lead to buckling (which would almost immediately lead to catastrophic failure). Each dive of this submarine to any appreciable depth would also result in micro cracks forming in the carbon fiber tube, particularly around the interface with the titanium ring where it would experience differential expansion/contraction due to dissimilar materials.

This was guaranteed to fail.

[–] • 2 pts (edited )

What I find confusing is this immense pressure is so much that a hole the size of a hair is enough to instantly kill them but they have recovered bottles of perfum still sealed... Logic says those bottles with glass caps and air pockets should have imploded but there they are, sitting in a museum.

[–] • 2 pts

That's easy to explain: there's a liquid in the bottles pushing back against the glass walls. It's likely that as the bottles sank, the higher water pressure from the ocean could have leaked into the bottles. This would equalize the pressure.

[–] • 1 pt

sealed with air still inside.

[–] • 4 pts

Pressure is measured in area kind of, pounds per square inch. A significantly smaller container doesn't go under nearly the same amount of stress as a larger one. I'd also be willing to bet if you compare cross sections, the smaller one would have more of its volume in the walls vs the submarine.

[–] • 2 pts

Kek, rest in piss (((OceanGate))) kikes and curryniggers.

[–] • 2 pts (edited )

Yep. CF is guaranteed to catastrophically fail for this use case. It is not an appropriate material based on material science and the repeated forces it would resist. It would continuously develop fatigue fractures until it reaches the point of material failure. Material failure means death in the span of milliseconds, if at depth.

[–] • 1 pt

Another problem with it is that the development of fatigue fractures is stochastic, so the progression to failure is virtually unpredictable, as opposed to something more traditional like steel, where the failure modes under stress (from elastic deformation through plastic deformation to failure are well know and predictable). Although, in these extreme environments, any plastic deformation of a steel pressure vessel would also likely end in catastrophic failure.

[–] • 2 pts

I thought wound carbon fiber vessels were best in tension but not in compression