Undersea Pressure Vessel

[glevans]

I don't believe conventional pressure vessel design calculations are valid for composite cylinders exposed to high hydrostatic pressures, mainly due to the tendency of the fibres to buckle under compression. How should structural analysis be approached to establish the fibre type, wall thickness and fibre orientation ?

 

[rnd2]

With the possible exception of Kevlar and related aramid fibres, generally, fibres such as glass and carbon stand up to compression reasonably well. It is tension they are not so good at. Fibre orientation is most important.
If you are considering a fibre re-enforced cylinder you would be wise to physically test if that is possible.

 

[Lorenzomaterial]

Try a bidirectional (cross-ply) configuration.

 

[Compositepro]

Actually carbon fiber has exceptionally good compression strength and is even more exceptional in tensile strength. Compression strength is much more sensitive to the properties of the polymer matrix and fiber orientation. Unidirectional compression strength can exceed 200,000 psi.
The Navy is very interested in composite submarines.

 

[rnd2]

Compositepro is correct about tension. Disregard the second sentence in my post Aug 13. It is not correct.