Oceangate structural failure

As I suspected composite fibre pressure vessels do not prove reliable when subjected to external rather than internal pressure, delamination is likely to occur.
The video link below is worth study and thought.

**LINK**

Regards
John

Well yes, but posting a video "predicting" problems is not very useful after the vessel is lost. Posting the same video a year ago would have been impressive.

Martin

the more i hear about this the more i am convinced its was a peise of junk built by a fool

Thanks for sharing the link, John

Let’s hope that any discussion here remains technical … and that the thread is allowed to persist.

The subject matter [taken in the abstract] is interesting.

MichaelG.

One of their own employees expressed his concern at the lack of Non Destructive Testing of the pressure vessel but was dismissed from his employment, they had the necessary foresight within their organisation but chose to ignore it with the resulting catastrophe, you can take a horse to water but you can’t make it drink. Dave W

I used to have a book entitled 'the new science of Strong materials' by JEGordon, which points out the potential difficulties with fibre reinforced composites used in compression. Prof Gordon was born in 1913, so this is not a new phenomenon. I think one might find the book on the interweb as a pdf

The difficulty of testing a prototype could be finding a tank big enough which can generate 12000 psi, ie twice the depth of Titanic. The idea of acoustic detectors would have frightened me off, as soon as a structure like this starts to go, it goes catastrophically

For anyone wishing to fast-forward to the really important bit … it starts at about 10:40

As I have already stated [on the closed thread]:

[…] why I was so dubious about the acoustic monitoring system

If it detects any sound, it’s already too late … I would posit.

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MichaelG.

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Edit: __ this post crossed with Duncan’s … good to see we are of like mind.

Edited By Michael Gilligan on 09/07/2023 14:32:02

By the way, prof Gordon wrote another very good book, "structures, or Why Things Don't Fall Down"

Alas, the emerging evidence is that OceanGate were warned repeatedly during development that the vessel was unsafe. Mr Rush chose to ignore all the warnings and deliberately circumvent regulations, for example by describing passengers as "Mission Specialists". Said so openly and in public too.

Only became newsworthy after the accident, but multiple concerns were expressed well before the vessel failed. This was predicable.

I was surprised to find that the disaster has developed a political dimension. To me it's just another technical failure that we can and should learn from - there's the usual 'accident chain', albeit with an unusually high level of human error. Situation normal, do better next time.

However, seems the incident has upset the body of opinion who think that experts know nothing. Odd really, I find getting technical stuff correct works far better than ploughing on regardless. In my workshop I take advice, assess and mitigate risks, and learn from mistakes. Hardly controversial that I messed up on the lathe yesterday and have do the job again, properly this time.

Dave

Duncan

Prof Gordons books "The New Science of Strong Materials" and "Structures, or why things don't fall down" are still in print and available from Penguin.

Hardly surprising as they give an excellent explanation of how such things work with just the right amount of science for the ordinary intelligent reader to understand why things are the way they are whilst remaining accessible to just about anyone with an attention span long enough to cover 4 or 5 pages.

True classics and unlikely ever to become outdated.

Clive

Interesting video. Lots of other video and images used with no apparent referencing. I found the lmages of them apparently bonding a large metallic flange to the outside of a composite tube. This does not seem appropriate for the Titan pressure hull. However a short video on the OceanGate website (before it was shut down) appeared to show composite tape being wound on a mandrel complete with flanges. On the face of it starting with a metallic tube with integral flanges and wrapping it seems a better approach. The load paths in the flange area must be quite complex to say the least.
The fact that the acrylic window plug was missing from the recovered end bell is interesting. If it failed it seems unlikely to me that the rest of the hull would have failed. The window was a tapered plug so probably did not need or have much holding it in place. It is possible a shock wave (like water hammer) inside the end bell caused by the collapse of the main body tube disloged it.

I await the TSBC report with interest. They normally take about a year.

Robert.

I also found the video interesting. In response to Martin Johnson's comment on the video, I note that the thesis referred to near the beginning was dated 2012/2013, so that particular piece of information had been available for ten years.

In my mind I would have thought that anyone seriously considering a project of this nature would have researched all available information on any material that was being proposed for use in the project. Perhaps I am expecting too much.

At work we would always refer to the "Anti-Reality Bucket" that people sometimes put over their head. Did someone find the biggest one in the world for this project?

Neil

Proof testing each and every hull they made could have been simply to lower it to the proof depth in a deep enough ocean trench. This does, though, need a long enough length of string!

.

Long lengths of string are, of course available, but hiring the use of them is expensive.

MichaelG.

As reported in the ‘Daily Mirror’ :

The plane, a USAF C17, carried specialised tools provided by Magellan, an underwater research firm based in Guernsey.

The equipment includes a lifting device with a 7,000m synthetic rope and a remote-operated vehicle (ROV) capable of reaching depths of up to 6,000 meters.

The aircraft will fly the gear from Jersey to St John's in Newfoundland, Canada. The equipment was previously held in Jersey due to import issues into the USA.

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MichaelG.

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Ref. __ https://www.magellan.gg/

Edited By Michael Gilligan on 09/07/2023 20:26:53

The Krylov state reserch centre in Russia is the only place in the world to be able to test these things to full ocean depth plus a safety margin. I think they can put about 20,000psi on a sub of this size. But of course it costs and you have to be chummy with the Russians.

Wow !!

**LINK**

https://krylov-centre.ru/en/experimental/base-doccamers/

MichaelG.

Anybody else with the opinion that we may well see a similar situation with 'private' space trips/travel?

At least, if you're sucked into the vastness of space i the event of capsule failure you are actually in a seat.

Re Titan, yet again hindsight is a great teacher and there are now plastic(?) model construction kits available.

Regards Ian.

An Article in the NewYorker magazine summaries some of the concerns raised about this. Including the empolyee who, in the end, was sued by Rush and had to withdraw his complaint.

(Hopefully it is still available. )