Re: [PSUBS-MAILIST] Viewport Toughness

[Warren Greenway <opensourcesub@yahoo.com>]

I'm chuckling over the responses to my message. Sorry
if anyone thought I was advocating the use of glass,
I'm not. Glass has a lot of manufacturing issues. What
I was pointing out is that acrylic becomes brittle 
under pressure and fatigues around imperpections, 
building up very high localized stresses. The
solution?
Overbuild as much as possible.

Warren.

--- Warren Greenway <opensourcesub@yahoo.com> wrote:
> Acrylic is as bad as glass when it comes to
> shattering.
> Acrylic was chosen for viewports originally because
> it
> was so much easier to form then glass. Acrylic
> fatigues,
> and is very likely to shatter like glass under
> pressure
> if you have a scratch or nick in it. I went over
> this
> with an experienced plastics engineer, he also said
> that the plastic shouldn't be used without annealing
> (heat-treating).
> 
> Warren.
> 
> --- Brian Cox <ojaibees@ojai.net> wrote:
> > I have a question about using a glass dome,
> wouldn't
> > a thick glass dome actually stronger than acrylic?
> 
> > But it would not be able to be used because of it
> > propensity to shatter under certain types of
> > stresses.    Adam ?
> > 
> > Brian Cox
> >  
> > ----- Original Message ----- 
> > From: "Adam Lawrence" <adteleka@in-tch.com>
> > To: <personal_submersibles@psubs.org>
> > Sent: Monday, October 06, 2003 7:30 AM
> > Subject: Re: [PSUBS-MAILIST] Viewport Toughness
> > 
> > 
> > > From what I have read, when a viewport breaks it
> > starts by extruding itself
> > > into the flange and then final failure is like a
> > shotgun going off. Also,
> > > failure initiates on the inside surface, where
> the
> > acrylic is in tension.
> > > Test it, that's the only way you'll know!
> > > 
> > > Adam
> > > 
> > > 
> > > ----- Original Message -----
> > > From: "pierre&marie"
> <poulin.carrier@videotron.ca>
> > > To: <personal_submersibles@psubs.org>
> > > Sent: Monday, October 06, 2003 5:49 AM
> > > Subject: [PSUBS-MAILIST] Viewport Toughness
> > > 
> > > 
> > > > Hi People!
> > > >
> > > > I've been to a house building show here in
> cold
> > Canada and there was a
> > > boot
> > > > that sold "unbreakable" windows for thief.
> > > >
> > > > They say that there technologie can change a
> > normal window into a bullet
> > > > proof window.
> > > >
> > > > The basic of that method is to put a high
> > resistance thin plastic film
> > > that
> > > > stick on the window. Almost like a windshield.
> > You should see me comming
> > > > from now... I asked if we can put that film on
> > acrylic and the said yes.
> > > >
> > > > Do you think that this could be helpful for
> > psubs? It would not augment to
> > > > strenght of the viewport but if it break it
> > could prevent water from
> > > comming
> > > > inside the sub or prevent the viewport from
> > imploding?
> > > >
> > > > Comments?
> > > >
> > > > Pierre "Viewport Strenghtener Technicien"
> Poulin
> > > >
> > > 
> > > 
> > 
> 
> 
> __________________________________
> Do you Yahoo!?
> The New Yahoo! Shopping - with improved product
> search
> http://shopping.yahoo.com


__________________________________
Do you Yahoo!?
The New Yahoo! Shopping - with improved product search
http://shopping.yahoo.com