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

Hi Eliezer,

FRP's/ GRP"s work well with many different types of core materials that extend their
stand alone physical properties.
 The Navy has been working with Alumina-boride ceramics with some rather
dramatic results. They have pressure vessels with approximately half inch
hull thickness that have been proven to depths of 20,000 feet or better.
 If anyone is interested I'll see if I can dig up my data on the subject or
you can order the full report from Jerry @ Hydroports.Com - Engineering support for undersea operations



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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