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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 g
by hef19898 3y ago
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 with the article and the first spurce video:
- The view port was not rated for the intended operating depth, if true I am out of words...
- the pre-preg material was apparently beyond shelf life, if true almost as bad as the view port. When pre-preg is beyong shelf life, the resign doesn't reliable bond anymore. That means basically delaminated layers before the "vessel" saw water for the first time
- 480(!) layers of carbon fibre, that carries the risk of prematurw dryong of the resin during production. Impact, see above.
- not curing and no auto-clav, again with the same results as above
- The mating rings for the emd caps have been glued on. Nothing wrong with that per se, but a bond supposed to sustain repeated dives to 4,000 m needs to be very precise. Ocean Gate applied the glue manually by hand, with inconsistent thickness in a non-clean enviroment. No idea to which tolerances the CFC hull and rings have been machined, but based the video of the bonding (they used chains attached to gate crane) they didn't seem to be too precise. The results are a high potential of foreign objects and debris being glued in, non-defined wiggle room between the CFV hull and the titanium rings and end caps and yet another strucural weakness of the vessel.
- they also used titanium fibre. If trued, it doesn't matter because the preasure was applied from the outside, all the tensile streangth of carbon and titano fibers only worls against preasure from inside the vessel.
- No back-ups, exposed wiring at the outside, flamable material at the inside, no telemetry, no emergency beacon, only wireless (!) controls (and they didn't even do enough testing to find key mapping errors of their Logitech controller...)
- 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)
- Safety culture: completely absent, to the point of being proud about it. Unable to distinguosh between vessel certification and proper operations (there is a reason that aerospace certifies the design, production, maintenance and operations organisation seperately), firing people raising concerns, I am out of words here..
- The vessel can only be opened from the outside (!), so even a perfect dive can lead to suffocation is the vessel isn't located fast enough...
I could go on, but calling this abomination "engineering" is an insult to the universe.
Finally, some potential failure modes:
- the view port (obviously)
- the hull (delamination, stress, bad material, intentionally induced defects...)
- the bond between the rings for the end caps and the hull (weakened bond due to different deformation of the two materials, weak bond due to foreign objects, inconsistens bond due to bad application of the glue...)
All in all, from design over manufacturing to maintenance and operations, this thing was a death tral whos only upside was a quick death in case of an implosion.
- bboygravity 3y ago> 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.
- hef19898 3y agoThe first thing I saw of Titan, while lookong for some footage of the infamous controller, was two screenholders, and that lightbar fr AliExpress or something, directly screwed into the inside of the hull... I honestely do not know what to say about all of this, which is actually pretty rare. I pitty the other four passengers, Rush got what asked for, and rightly so.
- carrolldunham 3y agoIt was screwed into a floating inner liner cylinder which you can see in any video is separated from the hull. Get the facts straight before sounding off with gleeful incredulity.
- hef19898 3y agoJust rechecked a video, and there is some kind of liner used, to which the equipment is attached. I stand corrected. There is nothing gleeful in any of my comments so, quite the opposite, I am really sad. Amd getting the facts straight requires a proper investigation, one that is happening. What I did was a superficial "FMEA" based on whatever, incomplete, information was publicly available at the time. Some is wrong, some is missing and some comes straight from OceanGate / Rush himself.
- 2-718-281-828 3y ago> That and the fact that it actually made it to Titanic a few times and back without catastrophic failure. i've no idea what i'm talking about but my guess would be that they were sort of aware of the design shortcomings and then just tried to compensate by overengineering the static components. and then they just pretended the material wouldn't progressively deteriorate towards the inevitable demise.