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Looks like The Titanic killed a few more people

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eelw said:
But wouldn’t that tiny hole compromise the structure and collapse it?
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I'm not a sub-ologist but I'm pretty sure even at half the depth of the titanic, the pressures are so high that a pinhole will cause near-instant explosive decompression. The water simply gets replaced with water and tears the whole thing apart.
 
eelw said:
But wouldn’t that tiny hole compromise the structure and collapse it?
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Not necessarily, things popping like balloons is more movie than reality for a lot of things. It would impact the hoop stress carrying ability, but at the same time pressures would start to equalize. It just depends on if the remaining structure could still carry the hoop stresses without buckling.

Somewhat similar to a high pressure hydraulic line getting a crack in it, they don't generally just open up like a latex balloon.

(Note, I've never worked directly with negative pressure vessels, just positive ones but the loads are similar just in compression instead of tension)
 
Zorba said:
Not necessarily, things popping like balloons is more movie than reality for a lot of things. It would impact the hoop stress carrying ability, but at the same time pressures would start to equalize. It just depends on if the remaining structure could still carry the hoop stresses without buckling.

Somewhat similar to a high pressure hydraulic line getting a crack in it, they don't generally just open up like a latex balloon.

(Note, I've never worked directly with negative pressure vessels, just positive ones but the loads are similar just in compression instead of tension)
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And what would happen if the high pressure line had an infinite amount of air available behind it? 'Cuz that's pretty similar to the ocean entering that sub at 6,000 psi.
 
Zorba said:
Not necessarily, things popping like balloons is more movie than reality for a lot of things. It would impact the hoop stress carrying ability, but at the same time pressures would start to equalize. It just depends on if the remaining structure could still carry the hoop stresses without buckling.

Somewhat similar to a high pressure hydraulic line getting a crack in it, they don't generally just open up like a latex balloon.

(Note, I've never worked directly with negative pressure vessels, just positive ones but the loads are similar just in compression instead of tension)
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From what I read the owner did not want to subject a hull to destructive testing to see if/when it would fail from the use they had in mind. Given the novelty of the design that seems like a considerable mistake since they don't know what they don't know even if the carbon fiber tube was manufactured absolutely perfectly (there are indications it was not).
 
[DHT]Osiris said:
And what would happen if the high pressure line had an infinite amount of air available behind it? 'Cuz that's pretty similar to the ocean entering that sub at 6,000 psi.
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It'd keep spraying. I've seen 4,000 psi thin walled hydraulic tubes crack and maintain 4,000 psi for minutes. Something needs to be there to keep the crack from growing as the edge of the crack has a very high stress riser, but carbon fiber has that naturally as the crack hits new fibers. Mild steel and AL can locally yield at the crack edge preventing it from further growth without extra load.
 
Vic said:
Hate to say it but I already got a super bad feeling that we're gonna end up knowing more abo
skyking said:
And yet people would rather talk about Amelia Earhart.
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K1052 said:
From what I read the owner did not want to subject a hull to destructive testing to see if/when it would fail from the use they had in mind. Given the novelty of the design that seems like a considerable mistake since they don't know what they don't know even if the carbon fiber tube was manufactured absolutely perfectly (there are indications it was not).
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The next question is the structural integrity of the submersible after each trip down to Titanic. Is it a one and done vehicle that loses structural integrity with each deep dive? It's starting to look that way.
 
BoomerD said:

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It's amazing the power of differential pressure. It caused the death of a submariner on one of the Tridents when a hatch, that weighs more than a ton between the forward compartment and missile compartment crushed a sailor due to probably no more than a pound and a half of difference between compartments. It was a pain in the butt when they modified the hatches with dampers because one of them was right after the entrance to the Fire Control Center, which is where I spent a lot of my time.
 
Hans Gruber said:
The next question is the structural integrity of the submersible after each trip down to Titanic. Is it a one and done vehicle that loses structural integrity with each deep dive? It's starting to look that way.
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I'd be curious to know what the company thought the service life of it would be or if they even bothered to consider it.
 
Debri field probably means it imploded if the debri is actually from the submursible. My bet is on the stress of the viewport window or hull.
 
K1052 said:
I'd be curious to know what the company thought the service life of it would be or if they even bothered to consider it.
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The company used a wireless logitech gaming controller and what looked like an elevator button for navigation. You have to use hardwired systems and have redundancy backup systems. The vehicle made it down to Titanic multiple times. I think with each pressurization cycle the structural integrity of the submersible was significantly weakened by the pounds per square inch pressures 12,00ft down.

Airplanes have a useful life cycle of landings and takeoffs. Once they reach that limit of takeoffs and landings, they retire the planes. It's the pressurization of the planes that weakens the aluminum over time. I think the lifecycle of airliners is 30,000+ takeoff/landing/pressurization cycles.

The news is saying they found a debris field. That would mean the cork popped on the structure on the way down which would explain why all communication was lost.
 
sze5003 said:
Debri field probably means it imploded if the debri is actually from the submursible. My bet is on the stress of the viewport window or hull.
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Yeah, if the reports on the view port are true and it was only rated it 1300m, it may have been able to survive a couple dives to full depth, but fatigue caught up to it.
 
Zorba said:
Over load failure, 6 fittings 3 aluminum and 3 CF, all 6 failed. The carbon fiber ones were demonstrated to have higher strength than designed.
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I know that one of the big failure points when Lockheed was trying to develop the X-33 rocket plane was the use of carbon fiber LOX and H tanks. Hydrogen would seep into the fiber matrix and expand when no longer cryogenic and delaminated the tank material. One of the Lockheed engineers warned it would probably better to just stay with tried and true 2 walled stainless. Program was scrapped. Aerospike engine and all. I was so looking forward to going out to Moses Lake where it would have it's maiden flight.
Edit: still hope for the aerospike engine.
www.popularmechanics.com

The Elusive Aerospike Engine Could Finally Be Ready to Fly

After 70 years of fits and starts, is the long-promised nozzle design a reality at last?
www.popularmechanics.com www.popularmechanics.com
 
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