I see alot of talk of implosion and instant death.

I have some experience designing and testing pressure housings for high external pressures. Sure catastrophic implosion is a possibility but so is a seal opening up or a somewhat more gradual leak. Lets hope it was the former.

I am still suspicious of that titanium carbon fiber Butt joint, but just speculation

Perhaps of interest (old articles):

https://www.compositesworld.com/news/oceangate-ceo-pilots-carbon-fiber-submersible-in-4000-m-solo-dive

https://www.geekwire.com/2020/oceangate-picks-toray-cma-make-carbon-fiber-titanic-worthy-submersibles/

I don't want to wait until 3:00. I want the coast guard update now!

I suspect a slow(ish) leak at the carbon fibre - titanium glued lap joint. The elastic modulus mismatch of these 2 materials means that they move at different rates when exposed to loading (external pressure in this case). I’ve used engineering adhesives in downhole tools for 15 years. These tools see as much as 15000 psi (3 times the hydrostatic pressure at the titanic) but the loading scenario is different.

It sounds like this may have the 2nd best case conclusion, the best case being finding those on board alive and unharmed. In this case, the families can get closure (if the debris is indeed from the submersible).

I’m surprised there is a debris field if my suspicions are correct - the sub should be mostly intact.

We will see.

debris field means it was over in the blink of an eye.

so at least no suffering.


expect a discovery channel documentary within the year.

https://www.dailymail.co.uk/news/article-12223805/Debris-field-discovered-search-area-near-Titanic.html

What type of tools did you work on? We may have been over this, but that is my background as well. Did a lot of work on downhole load and vibration measurements tools as well as some rotary steerable development.

5.5 ksi is just getting started in the downhole world.

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At this point, implosion is - not good news, but the best of bad alternatives.

He is responsible. His statements and behavior are very worthy of disdain

the other thing to be suspicious of the carbon itself.

its very hard to build carbon fiber without any inclusions. and carbon fiber is carbon fibers in glue, ie its many layers of glue/fiber/glue/fiber ... all those layers compress and decompress with every dive. any imperfections in that, are stress concentrators, which, are site for crack initiation and propagation. so you compress and decompress this system, and you start propagating cracks.

it sounds like the sub was designed with some kind of acoustic emission monitoring system to listen in the carbon fiber to hear these crack popping. but there is no way to tell the size, shape, location etc of the cracks, just know they are happening.



this is why the guy was fired. he was hired to do non-destructive analysis on the hull, looking for inclusions/cracking and such. he said it was a deathtrap and was promptly fired.

so i mean, that, to me, sounds like the issue.



its also worthy to note that carbon fiber is not used in submarine design commonly.

Based on my experience, and I still own a a minority stake in a non-autoclave composite manufacturing company going on ten years, I think you are correct.

I'll wait for more evidence if we get any, but the signs are there. That, and have others have mentioned, the connection points between the composites and the other more traditional hull components are of concern.

As JYL wrote, this was the best of bad outcomes for the crew and passengers.

Debris confirmed to be from Titan. Consistent with implosion.

Hopefully, just as changes came about after the sinking of the titanic, we will see if the same for mini subs and similar. Guidelines, certifications, etc.

One point.

Implosion is not usually spectacular like Explosion.

The tube would have collapsed and the pressures equalized.

One end may have shot off and the contents spilled out.

I can’t understand the talk of a debris field.

This... The debris field they're chasing could be from the Titanic.

I've got a really bad feeling. This Sub may never be found.

Having no expertise in composites I am still a bit confused why the choice of carbon fiber here. Makes perfect sense if the pressure was internal.

Is light weight really an advantage for the vessel itself or does it just a convenience for handling operations?

Interesting paper 100% on subject, just skimmed but says tube started delaminating at pressure less than predicted by FE computational methods.
https://www.iccm-central.org/Proceedings/ICCM12proceedings/site/papers/pap631.pdf

Stick me in a Inconel, titanium of high grade stainless tube please. Save the composites for planes, bikes, and sportscar theatre

I just read part of the coast guard release.

The rear cap of the vessel has been found. The debris is likely whatever stuff was in the way of it as it rapidly detached.

http://forums.pelicanparts.com/uploa...1687462295.png

weight is important because only certain vessels (presumably the expensive ones) can handle heavier subs off the back. heavier, also makes them bigger. bigger again, you need more specialized (read: $$$) ships to handle it.

this thing seems to have tried to get around this with the submersible/towable support system too.

all about keeping the costs low. i wonder what doing it properly costs? wonder what a seat in one of these other submersibles that actually works costs? gotta be a million plus a ticket.

I think there are 2 reasons for carbon fibre…

1. This appears to have been designed by engineering students as a capstone project. I have been an industry panelist reviewing student Capstone Projects at SAIT since 2004. Without fail, every year, a group of students plans to make their project out of ‘Carbon Fiber, or Titanium, or both. This year was no exception with a group planning to make rear bumpers for comment vehicles out of carbon fibre to save weight…

2. In one of the reports I watched on this (I’ve been infatuated with this story), one of the experts said that making the body out of steel, the thickness and resulting weight made it impossible to achieve neutral buoyancy. I have not done any calcs to verify this.