Am I missing something about the Titan sub?
He used a carbon fibre pressure vessel. Carbon fibre is a material that’s good in tension. Is has no strength in compression at all: it’s just woven cloth.
It works as an aircraft pressure vessel because the pressure inside is higher than the pressure outside, hence the carbon fibre works as a balloon and is in tension.
But for a submersible, the pressure outside is higher. The pressure vessel is getting compressed.
So the carbon fibre will give it a bit of stiffness, but the actual crush resistance is being provided by the epoxy resin that holds the carbon fibre weave together.
Am I missing something? Why the hell did they build a compression pressure vessel out of string glued together? It doesn’t matter how strong the string is: it will still fold up if you scrunch it into a ball. The structural strength came not from the string, but from the glue.
I’m amazed it took as long to fail as it did. I must be missing something here, right?
Why, for the love of all that’s holy, did they use carbon fibre?
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Uraael
in reply to Sarah Brown • • •The answer to this lies in where the design originated. It was developed by adventurer Steve Fossett as a ONE-TIME submersible, which would have suited what he was using it for.
The company that now owns the design supplemented this with an active sensor system that would warn when any area was going to degrade/breach (apparently Carbon fibre degrades after every usage?). It either didn't work or the crew had no time to react to that information.
There's a brilliant thread about it somewhere. Will see if I can find it.
Sarah Brown
in reply to Uraael • •Uraael
in reply to Sarah Brown • • •Sion [main]
in reply to Sarah Brown • • •Sarah Brown
in reply to Sion [main] • •@Sion [main] Let’s say you have a T-shirt and you put a titanium ring at each end.
Will it stand on end (the rings laying horizontal) and hold your body weight?
Sion [main]
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Sarah Brown
in reply to Sion [main] • •Sarah Brown
in reply to Sarah Brown • •Bethan M. Jenkins
in reply to Sarah Brown • • •Sarah Brown
in reply to Bethan M. Jenkins • •Naomi
in reply to Sarah Brown • • •The other obvious flaw, besides being made of a material that is notable for being strong in tension, not compression, is the use of a cylinder for a vessel that is going to experience pressure from the outside, not the inside.
Just suck the air out of an empty lemonade bottle, and you'll see how little of a pressure differential is needed for the cylindrical center section to squash flat, while the spherical ends keep their shape. Thicker walls are only going to do so much to prevent that.
That's why cylindrical submarines used down to hundreds of feet have bulkheads at intervals along their length to support the cylinder from the inside.
And submarines that are used at thousands of feet of depth are made up of spherical pressure vessels, because additional bulkheads and thicker walls cease to reinforce cylinders sufficiently at depths where the slightest imperfection can result in deformation, that /will/ progress further under those forces. Even submarines that look cylindrical from the outside, like the DSRV:
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