-Ok I’ll dork out for you all after briefly skimming over that video. One thing that pops into mind is the lack of a torque plate bolted to the top of that titanium ring as its being bonded to the CF center tube.
-Torque plate meaning a ring of similar thickness and material (also titanium) as the flange of the cap/door which would eventually be bolted shut for the voyage, simulating distortion of the flange under fastener load.
-There’s a 19mm bolt every 270mm around the perimeter of the flange (est.) which will distort both flanges upon torquing, with the severity of distortion increasing nonlinearly with increases in torque.
-Door flange fastener torque might seem unimportant on a device under constant external pressure, but any distortion of the flange surface without an MLSS crush gasket (OG appeared to have just an o-ring) between the two halves could provide an opening for water to enter as pressures increase. Keep in mind, the same pressure is at work on the tiny gap between the two flanges trying to separate them.
-Also, even with a torque plate, the distortion will be simulated only under load. The titanium outer ring is bonded to the CF inner tube with an adhesive. That adhesive will cure either under distorted torque load with a plate, or without it.. and it’s bond will be severely stressed when in its opposing state. Meaning even if there were a torque plate, removing the plate after curing the adhesive would stress the bond between the two materials even at 1bar, opening weak points in the vessel.
-Also, the dissimilar materials (Ti and CF) expand and contract at dissimilar rates with variations in temperature. This material ROC could surely compromise the adhesive bond (only bond) between the two.
-While I’m still a long ways from 50, perhaps this is what some of those other uninspiring white engineers warned Mr. Rush about when designing this sub.
-All these points were surely discussed ad nauseam and dismissed during design, but are worth bringing up now since it failed and everyone is dead.
I think it was that tongue and groove joint they made that created a weak point and failed. The titanium should have been manufactured to encase the entire edge and at a much further depth. Even still, it shouldn’t have font that deep without proper testing. Heck, it may have been approved for one or two dives to that depth before it was decommissioned. Well the looking glass wouldn’t have been.