Re: [PSUBS-MAILIST] Composite pressure hull?

[Ian Roxborough <irox@ix.netcom.com>]

Take a plastic 1 litre soda bottle, to can pressurize it to a 
couple of hundred PSI and it won't burst, but you can almost
crush it with your hand (when it's only got 1ATM pressue inside
it).

Even with your egg, if we assume the egg shell shares the same
properties as steel (I know it doesn't, but...), it will be able
to hold more internal force than external.

This is why most submarines have ribbing/framing on the inside
(although it could be on the outside as well).

If you are interesting a in relevant book, try to get:
   "Pressue Vessels: External Pressure Technology"
                             by Carl T.F. Ross.

It's a little on the advanced side, but it does talk about composites
and aluminum pressure vessels.  Maybe somebody else can recommend a
more introductory book on pressure vessels under external forces.

Ian.

On Mon, 13 Oct 2003 08:27:22 -0700 (PDT)
Bob Duncan <katsurencho@yahoo.com> wrote:

> Seems to me it would be like a chicken egg. The more pressure on the inside the more likely it is to rupture. A chicken egg can handle outside pressure.
> 
> Ian Roxborough <irox@ix.netcom.com> wrote:On Sat, 11 Oct 2003 13:24:10 -0700 (PDT)
> Bob Duncan wrote:
> 
> > I'm afraid i probably won't be ready to start the design of my own submarine for another year. 
> > Alvin the deep sea research submarine designed by Al Vine of Woods Hole Institute uses a titanium pressure hull.
> > I have an intrest in designing a similar pressure hull, but using a relatively thin sheet or layer, of pure aluminum (1100 alloy), and wraping it with layers of roven woven (fiberglass cloth), and using epoxy resin. Which has been used in the marine industry for years. 
> > High pressure gas containers (both sphere and cylinders), have been around for years. They hold an internal pressure of 10,000 psi (working pressure). I would think this would be very feasible for an even higher external pressure. 
> > The areas of concern are the places where electric or hydraulic connections go thru the pressure hull.
> 
> (I think somebody might have already replied with the same info.)
> 
> A pressure vessel which can hold 10,000 psi internal pressure, will
> only be able to resist faction of that as an external pressure force.
> The modes of failure and the physics acting of the vessel will
> be very different for a vessel holding an external force verse a
> vessel holding an internal force.
> 
> Ian. 
> 
> 
> Two guiding principles govern Israel Naval Commando doctrine:
> 
> 1.Every defense system is vulnerable.
> 
> 2.The enemy can deal with weapons and operational methods that are known; for that reason, naval commandos use imagination, daring and initiative, to create situations which cannot be anticipated.
> 
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