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Re: [PSUBS-MAILIST] In my search for a simple, cheap pressure hull ...

In einer eMail vom 08.11.2001 20:56:01 (MEZ) Mitteleuropäische Zeit schreibt bayan_darkeyes@yahoo.com:

Hey Guys,
  I worked in the fiberglass industry for some time
as a plant foreman in a storm shelter manufacturing
facility. As a general rule, one can expect the tinsel
strength of standard composites to be 15 times that of
concrete, and 3 times that of mild steel. In
compression, the advantage is less. About 1:1 with
mild steel, and 4-5:1 over concrete. This is by
WEIGHT, not by thickness. The chance of making a
mistake in fabricating here, for anyone not VERY good
with these materials, is quite high. It is a hard
media to work with even if you are experienced with
it. Steel is SO much more forgiving. Also, composites
that are damaged, even minor amounts, are virtually
impossible to repair without leaving an uneven flex
and compression area in the structure. The problem
with that, I hope, is obvious. I for one think metals,
at least for p-subs, is the cheapest and easiest way
to go. Maintenance and monitoring are also much
simpler. One needs ultrasound or MRI types of NDT rigs
to inspect composites for integrity.

Hi Dewey, Hi PSUBers,

I´m agree with You. The advantage of fiberglass is the good ratio tensile strengh to self-wight...
I´m working in a firm designing big axial fans for windtunnels or powerplants. The decision to use fiberglass/coalfibers is not the price... (the are very expensive) but the less wight of this blades alows higher speed
a blade made by castalloy ore a hollow steel blade would be cheaper but the mass is to high...
but nobody will ever build the housings from fiberglass... the have to withstand the impact of an broken blade and so the are made of steel and heavy.
(like a SUB.... :-)) )

To reduce the posibillitys of fatal defects during hand making the fiberglass structures its able to use so called "preprecs" I know that the are used in the aircraft industry for the wings eg. this preprecs can be stored up to 1 jear under cold conditions. the resin is just between the fibers (in a gel condition) and on both sides are plastic films. the have there final thickness.
the prepracs can be processed in the same way like metal sheets in the car industry. put it in a mold, press it, warm it and ready....so I guess it might be possible to put this mats on a model shape...

but i don´t know if You can by it next door and how expensive this stuff could be....