Interesting fact about this tragedy is that a piece of debris in the new OceansGate debris field 1600 feet from the bow of the Titanic has a cover from the same submarine that fell off on a previous dive.

CF doesn't really bend and collapse like metal. When it fails it shatters spectacularly. If the tube collapsed it would pop the end caps like a Pillsbury tube.

I am very impressed with the knowledge base of you Pelicans! You are some brilliant and educated people and I am fortunate to be part of this community.

Rock on, David

https://youtu.be/4qe1Ueifekg

Simple compression experiment.

https://www.youtube.com/watch?v=fGFWMzwvOno

video has several photos of the construction, and dear lord, its worse even than we thought.

Sacred feces! I can envision a lot of regs coming down due to this epic failure.

Well, that was quite something. Thanks for posting that.

yeah that wrap is so much worse than i was imagining. it is so easy to have inclusions there, and its a weakest wrap.

as is the fitting on the end caps. the narrator is correct, one of the key problems with deep submergence is differential shrinks. its so bad that if you put like gold plated electrical connectors under there, the gold will flake off, because the differential shrinking. everything shrinks under load differently, and that carbon tube is going to shrink likely faster than the end caps, and that means you now have a shear line cracking at that seam. 6000psi might as well be a drill bit at that point.

i can't believe they didnt use like 1 inch thick titanium core, and then wrap that. or use a titanium outer sleeve over the whole thing and let that shrink and push on the carbon fiber.

like, yeah, this is not how you build submarines.

He admitted to breaking the rules of building a submersible from cf.

Rick, the way I'm visualizing it is, imagine if a steel rod is placed on one square inch of your body, and a 4,700 lb SUV dropped onto the other end of the rod. With thousands of other steel rods placed on all the other square inches of your body, and thousands of SUVs dropped on those rods. All at once. Those steel rods would instantly pulverize your body, flesh and bone alike, until they meet in what used to be your center.

Your body is 60% water anyway. I think the other 40% of you would instantly become disassociated particles, perhaps gooshing in all directions. That's just my morbid guess and the logic behind it.

This seems way more extreme than an astronaut suffering sudden decompression in space, because he's going from 14 psi to 0 psi, these persons instantly went from 14 psi to 4700 psi.

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Juan Brown is a 777 pilot and not an engineer but he has some good information. He is wrong about a couple things here like NDT of composites but the video is worth watching.

I sorta agree with you but not completely. The rail tanker implosion is not representative because it is steel. Don’t forget that the CF had already suffered some delamination. This (even more than usual) non homogeneous structure would have meant it likely wouldn’t just shatter. Sure the delaminated pieces would have fallen off but some would still remain attached to the main tube.

Carbon fibre delaminates and the thin layers rip. The damage is normally confined to the break, not everywhere…


http://forums.pelicanparts.com/uploa...1687547846.png

You know what could have happened though…

They heard a crack, and released ballast.

As they ascend, a small leak develops that floods the vessel and compressed the air inside the vessel. With a pressure differential of 5530 psi, a small leak can be pretty fast…

As they ascend further, the pressure inside the vessel becomes higher than the pressure outside the vessel.

At some point the pressure of the now compressed air inside the vessel is enough to blow the end off including all of the contents. Perhaps exploding the carbon fibre tube.

Mic drop.

Unless a now water laden vessel won’t float when atleast partially full of water.

An explosion like that from a 377 times volume change of that volume (20’ long x 7’ in diameter = 245 cubic feet compressed into .650 cubic feet) should have been easily detected by a listening device within a couple hundred miles…

I suspect they went with CF because it can be constructed with DIY methods (not well obviously but only an expert would know). Whereas titanium would require specialized tools and skills to construct anything with it.


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Here is a great You Tube Video showing the Titanic wreck close up.

Some remarkable video.

https://www.youtube.com/watch?v=tiVctx-121g

From Reddit:

<blockquote class="reddit-embed-bq" style="height:500px" data-embed-height="500"> <a href="https://www.reddit.com/r/ThatsInsane/comments/14glhqe/the_video_shows_how_titanic_sub_imploded/">The video shows how Titanic sub imploded.</a><br> by <a href="https://www.reddit.com/user/Genesis_001">u/Genesis_001</a> in <a href="https://www.reddit.com/r/ThatsInsane/">ThatsInsane</a> </blockquote><script async="" src="https://embed.reddit.com/widgets.js" charset="UTF-8"></script>

Sure except that's not how CF fails...

Fatigue modeling (remember it has successfully made it to titanic prior) of a thick wall composite (non homogeneous) tube under external pressure is an extraordinarily difficult problem for the most skilled of specialists, so forgive me if I don't trust that reddit video even the tiniest bit.

I was suspicious of carbon fiber as a reasonable material when I first heard of this, and after watching a bunch of interviews with experts it is 100% confirmed. Should have been made out of good ol' fashion linear elastic metal or very thick cast acrylic.

If you gotta be fancy find some way to print it by direct deposition.

Imagine how much it cost to buy and machine that giant piece of titanium. I wonder why they went with all these exotic materials, could a conventional sub, even way overbuilt, not survive?