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Re: [PSUBS-MAILIST] Prestressed concrete pipe



I love ferrocement for its chief quality, which is the ability to form a very stiff and strong structure that is also very thin.

Unfortunately, the more I study submarines the less I like ferro for the pressure hull. In compressively loaded structures, which fail due to structural instability rather than by crushing the material, thickness is a virtue because it resists buckling, so thin ferro is not attractive. And it's hard to make ferro thick (without building in voids) except by Iorn's lamination process, and that is slowwww.

So for the pressure hull, prestressed concrete starts to look rather good. Now for the outer casing that holds the main ballast tanks and other stuff and needs to have a fair hydrodynamic shape, ferro still looks very good. The pressure hull can be an ugly cylinder - nobody needs to see it. It just needs to be strong and keep the crew alive.

As for joining sections together, that's the next topic I need to research. There must be a way.


Best,
Marc

On 3/17/2010 11:24 PM, Brian Cox wrote:
Marc,
        If you could figure out a system for connecting them and making end
caps you would have an instant submarine!  It could be done, but why?   The
reasoning behind my ferro hull is that I was able to make a freeform shape
which is hydrodynamically advantages.  My shape also doubles as a ballast
and a structure to carry the actual pressure hull (which is steel).  So mine
is sort of a hybrid.  In my sub the wieght of the ferro cement will
contribute to the wieght I will need anyway so I figured that would help me
in that regard.  But working with the concrete is very interesting,  I had
some minor damage to the egdes of my ferro structure when I had to flip it
over using the fork lift  - to repair it all I had to do was mix up a small
batch of my cement mix and it was like new!  I'm looking forward to epoxying
the whole thing and adding some color !!




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