Why did the submarine implode?

Truly, the part of the pressure cell, which was constructed from carbon fiber composite, has failed. I don’t know any exact plan of the submarine with calculations. In my eyes, the choice of material has already been negligent. There are plenty of experiences with printed bodies made of steel, titanium and Plexiglas, for boats in this diving depth. I don’t know why the guy made this carbon thing. In my eyes an inappropriate material. Carbon fibers are embedded in epoxy resin to increase the tensile strength, shear strength and bending tensile strength. But the matrix is the epoxide. In my eyes, the reinforcement with the carbon fibers does not bring anything to the effect of pressure, since the fibers cannot absorb them. Thus, only the compressive strength of the epoxide matrix was purely mathematically. amounts to 70 – 130 N/mm2. Not bad, but not intoxicating for the purpose. The wall thickness should only have been calculated with low safety. (Apart from that the boat dived deeper than approved). Furthermore, the connection of the titanium parts to this carbon cell is a problem. I don’t know if he designed it with seals, or if the carbon cell was laminated with the titanium parts. I suspect that due to the very high water pressure with time water has migrated along the carbon fibers into the plastic structure and there has created plains and perhaps cracks. At some point, the cell was weakened. If he had made the cell clean from Plexiglas with the corresponding wall thickness, they would probably still be alive. The dip ball of the Trieste was forged from steel and later titanium was used for such purposes for weight reasons. I am absolutely sure that in the future such immersion cells can also be produced seamlessly with a 3-D printer, made of titanium powder, or steel powder. The current printers, (SLS) should be too small. I’ll go.