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The craft survived several launches - that proved it can do it. Whether it can do it reliably / survive fatigue accross repeated cycles is a different question
by cbzoiav 3y ago
The craft survived several launches - that proved it can do it.
Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.
- jfk13 3y agoWe already found out, I think.
- someweirdperson 3y agoMaybe some orcas played with it.
- hn_throwaway_99 3y ago> The craft survived several launches - that proved it can do it. Exactly, that's my point. I didn't realize that (this present catastrophe notwithstanding) that carbon fiber could even begin to have such compressive strength. How is the fiber formed in such a way to maintain that strength?
- jackmott42 3y agoalign layers of fibers in different directions and you can get strength in different directions. But it is tricky! The glue holding the metal end caps to the carbon tube is also a possible failure point. Imagine a metal ring slid over a carbon tube held on with glue. If pressure deforms the metal differently than the carbon, you get a gap at the interface and BOOM or if sea water degrades the glue, or if the carbon fiber degrades after each trip and eventually isn't strong enough any more, etc.
- Alupis 3y agoA point raised by James Cameron (and others) was the titanium bands mated to the carbon fiber hull. Apparently in the material science community, that's a huge no-no, and a well known one to boot. Galvanic corrosion or something like that...
- zarzavat 3y agoIt’s a dumb idea for numerous reasons. The titanium and carbon fibre will expand and contract in relation to temperature and pressure at different rates, they are two different materials with totally different material properties. So you’ve added a second force on the vehicle which is the pulling and pushing of the carbon fiber and titanium from one another. And all you have to hold that together is fancy glue, the glue is taking all that force. A 5 year old could do better.
- oofbey 3y agoIt’s counter-intuitive, but the so-called hoop stress on a cylinder being compressed from the outside actually results in tensile stress not compressive. This is because the material as it resists shrinking to a smaller radius is being pulled apart.
- hn_throwaway_99 3y agoIs this accurate? All of the examples I found online about hoop stress had diagrams where the pressure inside the cylinder was higher (as in a water pipe for example). Tensile strength would make sense in that scenario, but I don't see how it would apply when the cylinder is empty and being crushed by outside forces.
- Alupis 3y agoJames Cameron gave an interview where he claimed the carbon fiber hull concept was tested by a team competing to get down to Challenger Deep at the same time his team was - and the concept failed in testing. He also claimed many within the deep submersible community wrote letters to OceanGate warning them their plan was flawed and would result in catastrophic loss. Specifically, the failure mode was delamination. I can't vouch for how credible this all is - but, given how much disregard the OceanGate team had for safety, it doesn't seem too far fetched. https://www.youtube.com/watch?v=e9YB31ElEFQ https://www.youtube.com/watch?v=e9YB31ElEFQ
- hn_throwaway_99 3y agoThat was a great interview IMO, thanks for posting. I think some people might find it hard to both convey sympathy and compassion for the deceased and their families as well as being adamant that the submersible design was nuts (especially since the man primarily responsible died), but I think Cameron in particular did that very well.
- cbzoiav 3y agoChallenger Deep is exponentially more difficult than this - 10km Vs 4km so over double the pressure. While it may still be an entirely unsuitable material for 4km, not being suitable for 10km doesn't prove that.
- AdamJacobMuller 3y agoAs far as I'm aware, and please correct me if I'm wrong, they had never dove to this depth before. So, sure, it was launched before and recovered, but it never experienced the same conditions which caused the failure.
- mjb 3y agoThey did: http://web.archive.org/web/20200814020351/https://www.oceangate.com/our-subs/titan/titan-4000m-validation-dive.html http://web.archive.org/web/20200814020351/https://www.oceang... (At least twice, and probably more times).
- sitic 3y agoApparently it's at least 13 dives since 2021: https://www.geekwire.com/2022/beyond-the-titanic-oceangates-founder-contemplates-future-deep-sea-frontiers/ https://www.geekwire.com/2022/beyond-the-titanic-oceangates-...
- larrywright 3y agoI saw someone on Twitter suggest that this was probably WHY it failed this time. Each dive would weaken it.
- deleted 3y ago[deleted]
- distrill 3y agoi think we found out when it imploded
- ineedasername 3y ago>Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses. Seems like we already found out the answer is “no”. The overall ship design failed.
- deleted 3y ago[deleted]