Hi les! I had a deeper google into the
subject… and here is some more info, ill put the most relevant info first,
a lot are books which you would have to source from a library or purchase
possibly…
http://cat.inist.fr/?aModele=afficheN&cpsidt=15062369
- Optimum design of filament-wound multilayer-sandwich
submersible pressure hulls
Submersible pressure hulls with fiber-reinforced multilayer-sandwich
constructions have been developed in recent years as substitutes for classical
metallic ring-stiffened pressure hulls. This study aims to optimize the design
of filament-wound multilayer-sandwich submersible pressure hulls, taking into
consideration the shell buckling strength constraint, the angle-ply laminated
facing failure strength constraint and the low-density isotropic core yielding
strength constraint under hydrostatic pressure using the hybrid genetic
algorithm (HGA). The thickness of the facing, the thickness of the core layer,
the orientation angle of the fibers in the facings and the shear modulus of the
core material are taken as design variables. A sensitivity analysis is performed
to study the effects of the operational depths and the hull shell geometry
parameter, the length-to-diameter ratio (L/D), on the optimal design of
filament-wound multilayer-sandwich submersible pressure hulls with
graphite/epoxy, glass/epoxy and boron/epoxy composite facings. The results
reveal that the optimal weight of various sandwich pressure hulls increases
linearly with the operational depth, but it is almost unchanged as the geometry
paramter. Furthermore, Graphite/Epoxy is the best choice for the material of
the facings in a light-weight design. With reference to wall design,
Boron/Epoxy is the best choice for the material of the facing at shallow
depths, but Graphite/Epoxy is the best choice at extreme depths. Results of
this study provide a valuable reference for designers of underwater vehicles.
Ocean engineering ISSN 0029-8018
CODEN OCENBQ
In this paper, the effect of the width of winding band on the stability
of winding pattern is studied. Some key design variables are calculated to
optimize the dome geometry. The influence of winding process parameters on the
slippage tendency is also considered.
http://www.tech.plym.ac.uk/sme/composites/marine.htm
- Composite Materials and Structures for the Marine Environment.
(not directly submarine related, mostly composites use in ships)
http://www.eng-tips.com/viewthread.cfm?qid=174497&page=1
– A forum about Submarine engineering with some very good comments…
“Carbon fiber is
just that, a fiber. It's already very strong in
tension. Like any fiber, it has little strength in compression,
because the fibers are long and thin.”
“Now, as for making a submarine hull out of carbon fiber
_composite_, yes, it's possible. It may not be the best material for
the job. It's certainly not the cheapest.”
“Spend some time looking through ASME III (Unfired Pressure
Vessels) for vessels under external pressure. And keep in mind that
if you intend to operate at 100 ft (~45 psi) that you'll want a hefty margin
against any kind of pressure boundary buckling failure. Think in
terms of emergency recovery time from a depth overshoot if you experience
horizontal control plane malfunction while descending at some speed and down
angle when nearly at your maximum operating depth.”
“also look under ASME PVHO (Human occupancy) &
Sec. X {fiber reinforced plastic) pressure vessel codes”
http://www.deepflight.com/super_falcon.pdf
- A composite 2 person sub…looks like it might be pretty fast under water…
like a jet fighter! J
http://machinedesign.com/article/flying-underwater-0424
- another article about the super falcon
http://www.physicsforums.com/showthread.php?t=309701
– A forum discussing the physics behind pressure rating of pressure
vessels under compressive forces..
“You haven't
calculated buckling yet; any buckling would destroy the structure. Think of the
ruler. What you've calculated is non-buckling compression.
Buckling theory is relatively advanced, doubly so for 3-D structures. I haven't
worked in this area and can't recommend a reference. You might take a look at
Jones' Buckling of Bars, Plates, and Shells,
some of which is available on Google Books, to get an idea of the theory.”
http://www.physicsforums.com/showthread.php?t=24570
– Physics forum… “A circular window with radius 25 cm in a
submarine can withstand a maximum force of 1.23E6 N. If the interior of the
submarine is maintained at a pressure
of 1 atm, approximately how deep the submarine can dive without rupturing the
window? (You can assume sea water density of 1000 kg/m3.)”
http://www.physicsforums.com/showthread.php?t=272974
– And another physics question that is submarine and pressure related J
http://www.swri.org/3pubs/brochure/d18/StrucAnalysis/Structural.pdf
- A company that does pressure testing of submersibles in san Antonio texas! “SwRI has the capability to perform in-house or field
testing services. The staff has performed stress analysis test services for
commercial and government clients in many areas including boilers, pressure
vessels, submersibles, diving systems, composite housings, titanium instrument
housings etc”
http://www.defencetalk.com/forums/navy-maritime/cfrp-submarine-hull-material-5953/
- US Navy discussion about composite hull’s… Carbon fibre
Reinforced plastics
http://kkava.com/sub/ - Construction of a
composite UUAV (unmanned underwater autonomous vehicle) (lots of photo’s
of the molding process etc)
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Les & Anna
Sent: Saturday, 13 March 2010 4:22
PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] New
Guy from down under needs help
Thank you Stewart for your reply again I say to you
as I did to Alan a New Zealander who also answered my email, sorry for the
delayed reply been distracted for a while.
Yes it is the dream but as they say, not to dream is
to die ,at least on the inside anyway.
Respect and appreciate your comments and have taken them on
board. However as weight is a major concern for my requirements I will
still have that as my major criteria if possible.
By the way the sub pressure testing requirements bothers me
a little ..can you direct me where I might obtain some written data on
this.
I am all for maximum safety it is the major precursor
to all my design.........but I have incorporated at least
three back up systems for preventing slipping any deeper than 300 feet,
including auto surfacing beyond 320 feet as a safety factor. With this on
board the 3 times pressure factor seems over engineered.This I would
consider precludes a three times safety factor
By the way I think I read in the Stachiw book a
seven times factor for acrylic domes and windows?
Now my logic indicates to me that either they should be both
the same either way because the lesser will fail anyway so the maximum is
obsolete???
Appreciate the links and will follow up accordingly ...drat,
more reading and learning ..this sub stuffs a full house isn't it?
PS The reply from Alan James in N.Z .was
interesting, you may be interested to read...don't know if you also received
it? (just new at this sharing system)
PPS By the way where are you?, I am in Adelaide
S.A.
----- Original Message -----
Sent: Wednesday,
February 24, 2010 7:23 PM
Subject: RE:
[PSUBS-MAILIST] New Guy from down under needs help
Hi Les! Greetings from a fellow aussie J A light weight sub is
every person’s dream… But as you can probably tell it hasn’t
been done much before and to build a composite submarine in Australia is going to be very very
expensive if not impossible, you need an autoclave and plug big enough to fit
your sub in, or you build it out of smaller sections and join them, which
causes other problems.
Also your talking about wanting to
go to a maximum of 300 feet right? But you have to over build your sub to
ensure it is strong enough! Someone correct me if im wrong but I thought most
sub’s were pressure tested to 3 times their expected max operating depth
as part of their certification????
Also there is only one mode of failure
with a composite pressure vessel… and I would imagine with 150psi
pressing in from around you wouldn’t get much warning if something was
wrong with it other than a pop or crack and then nothing… because you
would be dead…
Here are some links I found, The military
and universities have been toying with composite sub parts and hulls but I
think for now your best bet would be to stick with steel or aluminum..
Composite air and hydrogen tanks sound/look like a good candidate but I
don’t think I would trust their reliability, and pressure from the inside
is different to pressure pressing in from the outside, Most of the
carbon/Kevlar tanks are spun formed over a mold/plug which is then heated and
pressure is put on..
http://www.ericgreeneassociates.com/images/History_of_Submarine_Composites.pdf
- History of Submarine Composites
http://www.bac.net.au/submarine.html
- An australian company that makes composite parts for the Collins class
submarines though they are not pressure vessel’s..
http://composite.about.com/library/weekly/aa990217.htm
- X-33 Composite Tank Problems, Complex shaped hydrogen tanks. Shows why
composite materials are so difficult to use for mission critical applications
and pressure vessels..
http://www.ctd-materials.com/products/tanks.htm
- Company that manufactures small composite pressure vessels, also lots of
pictures which give you an idea…
http://www.pentairwatertreatment.com/PentairFiles/Pentair%20Water%20Treatment/Literature/Composite%20Tank%20Sell%20Sheet%2042575.pdf
– Composite pressure vessels, some rated to 150psi
An example of one of their largest
tanks…
Opening : 16" 6”
operating pressure : 150psi/10.34bar
Height : 3695.7mm
Diameter : 1638.3
Capacity: 6057 Litres
Weight: 634kg
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Les & Anna
Sent: Wednesday, 24 February 2010
5:58 PM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] New Guy
from down under needs help
My name is Les, in Australia, I joined psubs almost a year
ago,after much much reading, and learning, an experience I am
sure that you are all aware, I do have a couple of questions that some-one may
be able to assist me with.
My aim is a specialized maximum depth 300feet 1atm sub, of
which weight is most critical, therefore I am considering the exotics such
as carbon fibre
and Kevlar .
1. Any experienced knowledge on these two
materials re this pressure 150psi that anyone can give me would be most
appreciated.
2. Any information regarding acrylic bubbles or more
precise half bubble or dome 4 feet (1200mm) to 6 feet (1800mm)diameter for this
depth and pressure, would also be
Looking forward to learning more