How ‘bout Boeing\U Washington engineering for air frame CF fuselage criteria was used to design the underwater craft. There was no direct design participation but the names and criteria could be hyped for a sales presentation?
Possibly, still blows my mind that any engineer for aerospace would think they could design a qualified submersible component, compressive stresses are literally 100% the opposite of tensile stresses.
The experience to understand either and what the pitfalls are takes years to develop in practical applications.
I am in nuclear and we analyze for extremes in both but I would NEVER presume I could design a submersible and I have been a submariner, 7 patrols, sub qualified.
My personal opinion after watching the construction of the device. Seeing them clue a titanium end bell to the CF tube made my head scream with alarms.
Titanium and CF will have different compression and expansion characteristics, and their overall compression and expansion under extreme pressure with have different rates (basically their overall movement relative to each other is different, this would cause them to pull apart in a way likely not fully understood or analyzed).
This would probably create fraying/cracking with the CF at the point where it is seamed into the titanium end bell.
I would guess after several deep dives this causes micro fraying in the CF and given the compressive strength comes from the resin matrix, not the fibers, that fraying would be enough to create a catastrophic failure once the crack was significant enough to propagate under extreme pressure.