re: Really good video here with James Cameron describing the Titanic submarine catastrophe.

quote:

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Carbon fiber is great for non structural parts but not so much for structural members.

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The problem here is application. Where you are definitely correct and why it's a poor application in a submarine is the cycle loading. With the pressures involved and the level of expansion and contraction, instead of deforming like a metal would in high stress scenarios, it fractures and not in a progressive way. Most metals before failure will bend, stretch, expand. Carbon fibre will reach the limits of the material and shear rapidly. In a sub that leaves zero safety buffer and rapid decompression. A very odd choice of material considering the application and safety concerns.

Great choice for F1 cars and their structural components. Strong, light, better than any metal. But it's unforgiving once it shears. In a sub, instead of protecting you better than any material available, it means a rapid death.