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


Why not use fiberglass combined with oak or marine plywood using the 
sandwicich method? As I understand the sandwich method provides more 
strength and flexibility. I got a couple of books about the subject but I 
haven't been able to find them, which has more info about the process. I 
also heard that even the goverment is experimenting with a special 
fiberglass for submarines which is comparable with titanium.


Eliezer Rodriguez
"The only thing in life to fear is fear itself."

>From: Ian Roxborough <irox@ix.netcom.com>
>Reply-To: personal_submersibles@psubs.org
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] In my search for a simple, cheap pressure  
>hull ...
>Date: Tue, 06 Nov 2001 13:51:36 -0800
>Hi all,
>I've thinking along the GRP lines for a while.
>Thought I'd pass along some information, mainly
>the material definition of GRP so any body using
>Alec Smyth's useful little spreadsheet can compare
>GRP to steel.
>Material definition for GRP (fiberglass matting):
>E = Young's Modulus : 65GPa or 9427121 psi
>Poisson's Ratio : 0.35
>Yield Stress : 1200MPa or 174039 psi
>Density : 2.1 g/cm^3 or 0.06387 lbs/in3
>The above data is from the book "Pressure Vessels
>external pressure technology" by Carl T. F. Ross.
>I think testing many vessels to collapse depth is
>key before trusting your life to a GRP based pressure
>Somebody meantioned using a cardboard tube as the
>frame for constructing a GRP pressure vessel.  Another
>more durable and maybe more useful method would be
>to use a section of large diameter corrugated polyethylene
>(or other plastic or GRP) piping, similar to piping
>used for drains in some areas.  Done correctly, the
>corrugations will form GRP hoops giving greater strength
>to the pressure vessel (the same as steel hoops on a metal
>pressure vessel).
>I'm hoping to start destructively testing some
>smaller GRP pressure vessels some time next year.
>If we share our test results we should be able to
>plot some nice curves and accurately compare the
>practical results to the math side of things.
>I'll also post a bio at some point as well.
>On Wed, 7 Nov 2001 07:37:52 +1000
>"Walter Starck" <wstarck@ozemail.com.au> wrote:
> > Phil,
> >
> > It would seem a fairly simple thing to lay up a series of small
> > composite vessels and test to collapse depth to get some idea of
> > variability and relative strength of  various resins, fibers, and
> > laminates.  Do you know if this has been done and if so are the results
> > accessible?
> >
> > Walter Starck
> > Golden Dolphin Video CD Magazine
> > of  diving and underwater photography
> > www.goldendolphin.com
> >
>Stop killing everything.

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