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Engineering assessment of the OceanGate Titan failure

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Re: Engineering assessment of the OceanGate Titan failure

#11

Post by hef19898 »

icegreentea2 wrote: post #7
rich_sasha wrote: post #2

I know nothing, literally nothing, about material engineering, past what I can skim off wikipedia and ingest on cycling websites. But I always thought composite nonmetal materials are hard to test nondestructively, which is the main limiting factor for their use in aerospace. Metals can be X-rayed to assess their condition, carbon not. Is that wrong? What am I missing? Just curious.

You can ultrasound and radiograph CF to do NDT. I think the challenge is just more that we have over half a century headstart working with Al in aircraft to understand their failure modes and how to adequately test for them. Our understanding of CF (+CF's inherent nature of having more sudden failures) makes designing adequate NDT regimes more challenging. That said, we are seeing much more CF (and CF composites) bei…

The whole fusselage of the 787 and A350 is composite, not just the wings. Composite wings are old news.

Strutural repairs are tricky so.

Re: Engineering assessment of the OceanGate Titan failure

#12

Post by ChuckNorris89 »

MobileVet wrote: post #3

> From all available sources, it is apparent that the viewport was designed and certified down to a depth of 1300 meters, not 4000 meters. Wow. What kind of hubris could look past that huge red flag? Apparently the kind that thinks it is interesting that it deforms by several inches and not scary

>Wow. What kind of hubris could look past that huge red flag?

The "bad-boy" disruptive innovator kind that doesn't play by the rules and that's worshiped in SV because he makes his wealth playing fast and loose around old stuffy bureaucratic regulations made by "evil old men" to gatekeep innovators like him from entering the naval market held by centuries year old corporations who actually know what they're doing.

The problem for him was that, unlike consumer tech, the laws of physics can't be disrupted. He'd tell you that himself if he'd still be alive. Shame that four other people had to perish to prove him wrong.

Re: Engineering assessment of the OceanGate Titan failure

#13

Post by JKCalhoun »

MobileVet wrote: post #3

> From all available sources, it is apparent that the viewport was designed and certified down to a depth of 1300 meters, not 4000 meters. Wow. What kind of hubris could look past that huge red flag? Apparently the kind that thinks it is interesting that it deforms by several inches and not scary

Sounds like a simple experiment to build a titanium sphere and fix the same spec'ed viewport on it and send it down to 4000 meters.

Perhaps a lawyer for a plaintiff with deep pockets will call for such a demonstration to be performed.

Re: Engineering assessment of the OceanGate Titan failure

#14

Post by ramesh31 »

ceejayoz wrote: post #4
rich_sasha wrote: post #2

I know nothing, literally nothing, about material engineering, past what I can skim off wikipedia and ingest on cycling websites. But I always thought composite nonmetal materials are hard to test nondestructively, which is the main limiting factor for their use in aerospace. Metals can be X-rayed to assess their condition, carbon not. Is that wrong? What am I missing? Just curious.

I don't think you're missing anything. Others, including those in-the-know, were left scratching their heads too. https://www.nytimes.com/2023/06/20/us/oceangate-titanic-miss... > Years before OceanGate’s submersible craft went missing in the Atlantic Ocean with five people onboard, the company faced several warnings as it prepared for its hallmark mission of taking wealthy passengers to tour the Titanic’s wreckage.…

My question is just... why?

It's not like carbon fiber was any cheaper than just making the thing out of steel or titanium like literally every other submersible. It just doesn't make any sense. You have none of the weight penalties that exist in aviation, so the heavier and the thicker the better.

Re: Engineering assessment of the OceanGate Titan failure

#15

Post by JKCalhoun »

ChuckNorris89 wrote: post #12
MobileVet wrote: post #3

> From all available sources, it is apparent that the viewport was designed and certified down to a depth of 1300 meters, not 4000 meters. Wow. What kind of hubris could look past that huge red flag? Apparently the kind that thinks it is interesting that it deforms by several inches and not scary

>Wow. What kind of hubris could look past that huge red flag? The "bad-boy" disruptive innovator kind that doesn't play by the rules and that's worshiped in SV because he makes his wealth playing fast and loose around old stuffy bureaucratic regulations made by "evil old men" to gatekeep innovators like him from entering the naval market held by centuries year old corporations who actually know what they're doing. Th…

> that's worshiped in SV

No need to generalize. (In fact as I understood it he haunted the Pacific Northwest.)

Re: Engineering assessment of the OceanGate Titan failure

#16

Post by JKCalhoun »

nonrepeating wrote: post #9

One can take comfort from this in a perverse way. The failure of the submersible was entirely predictable and should surprise no one. The alternative would be more troubling.

And perhaps like the Tacoma Narrows bridge it will end up being a cautionary tale for future engineers.

Re: Engineering assessment of the OceanGate Titan failure

#17

Post by bboygravity »

hef19898 wrote: post #8

After an initial reluctance to follow this story, mostly due to the hysterical media coverage of a pointless rescue operation, my engineering half of my brain got interested. I am by no means a materials engineer nor a naval architect, but I was involved in some Design FMEAs and wrote thesis about the manufacturing of structural, pressurized aerospace carbon fiber parts. Some things I came across, which are in line w…

> Despite claiming otherwise on their homepage (archive.org still has it) they did attach equipmwnt directly to the carbon hull on the inside by screwing (!) to the hull. Result, all the fibers cut by the screws don't take any load whatsoever anymore, increased risk of delaminations (the hull is compressed, the screw on the inside isn't)

This one is actually the most mind-blowing to me if true.

That and the fact that it actually made it to Titanic a few times and back without catastrophic failure.

Re: Engineering assessment of the OceanGate Titan failure

#18

Post by SV_BubbleTime »

ramesh31 wrote: post #14
ceejayoz wrote: post #4

Earlier quoted context omitted.

I don't think you're missing anything. Others, including those in-the-know, were left scratching their heads too. https://www.nytimes.com/2023/06/20/us/oceangate-titanic-miss... > Years before OceanGate’s submersible craft went missing in the Atlantic Ocean with five people onboard, the company faced several warnings as it prepared for its hallmark mission of taking wealthy passengers to tour the Titanic’s wreckage.…

My question is just... why? It's not like carbon fiber was any cheaper than just making the thing out of steel or titanium like literally every other submersible. It just doesn't make any sense. You have none of the weight penalties that exist in aviation, so the heavier and the thicker the better.

As I understood it, you do have a weight penalty for a sub. You need to get back up by powered movement, or down by it. You are limiting your dive time either way.

They can’t use foam for flotation at that depth. There is a concrete like “synthetic foam” if you want unpowered rise to surface but it’s expensive. I read early on they wanted carbon to be light enough to get back up by releasing weights on powerloss.

From what I have seen of the hull, it was a tube. I can’t remeber seeing a view with a complex or even drafted shape to it.

I suspect that spinning carbon by fiber would take far too long, and think they probably used narrow weave to do it. It would have been cheaper than the required thickness of titanium, which is the same strength as steel, but 40% the weight and still a little heavier than aluminum.

Who knows!? Nothing they did showed that they ever chose the more expensive option. Carbon was likely just the cheapest thing they could use for their goals.

Re: Engineering assessment of the OceanGate Titan failure

#19

Post by SV_BubbleTime »

jamincan wrote: post #6
MobileVet wrote: post #3

> From all available sources, it is apparent that the viewport was designed and certified down to a depth of 1300 meters, not 4000 meters. Wow. What kind of hubris could look past that huge red flag? Apparently the kind that thinks it is interesting that it deforms by several inches and not scary

It's pretty much 1/3 the depth which is suspiciously close to a 3x safety factor which is what I've always heard engineers use. They certainly seemed cavalier with safety, so it wouldn't surprise me if they reasoned about it in that way.

A rocket might have a factor of safety of around 1.1. This is because at 1.3, they’ll never leave the ground. This is why they are so carefully monitored and tested, and still fail.

It’s all relative. Good engineering doesn’t mean higher number.

No one knows what the FOS for this sub was. Given the information from the CEO, things like that were just slowing down innovation!

EDIT: Not all rockets, just using an example.

Re: Engineering assessment of the OceanGate Titan failure

#20

Post by hef19898 »

JKCalhoun wrote: post #15
ChuckNorris89 wrote: post #12

Earlier quoted context omitted.

>Wow. What kind of hubris could look past that huge red flag? The "bad-boy" disruptive innovator kind that doesn't play by the rules and that's worshiped in SV because he makes his wealth playing fast and loose around old stuffy bureaucratic regulations made by "evil old men" to gatekeep innovators like him from entering the naval market held by centuries year old corporations who actually know what they're doing. Th…

> that's worshiped in SV No need to generalize. (In fact as I understood it he haunted the Pacific Northwest.)

Well, as the first video in the submitted article points out, this move fast and braek things attitude, safety and professional standards be damned, is infecting the real world now. Besides my utter disdain for hype, that is the main problem I have with Musk, for me he is the main culprit in normalizing those otherwise unacceptable practices.

I hope it changes, bacause as we have seen it kills people, litterally. Titan was actually worse than Titanic, because the engineering of Titanic was actually sound for the time, saftey procedures and seamanship were not. The latter changed significantly after the Titanic, lets hope that this SV stained engineering culture will, too, after Titan.

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