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Re: [PSUBS-MAILIST] Eggshell and pressure
>From: Jari Siikarla <jari.siikarla@vertex.fi>
>
> >"the crush depth of an egg".....
>
> Weird.
Is that in reference to me? to you? to your friend?
Or a rhetorical weird? [ just kidding...I hope ]
>I was looking into this for a friend of mine working
> in biology lab in university.
>
> http://aci.mta.ca/TheUmbrella/Physics/P3401/Investigations/EggBreakACR.html
>
> In this page was found out that egg breaks at approximately 5kg's
> point load (10 lbs). This corresponds to 1.1 MN/m^2 pressure
> 1.1 MN/m^2 = 11 bar = 110 meters of fresh water (360 ft)
>
I came across similar references and should have noted it in my
message. I believe in raw eggs there is an egg sack or sheath
covering the albumin and yolk and an internal pressure exerted
outward.
However, I was hoping some "weird" person at Scripps
or Woodshole had actually tested an egg in one of their descents.
> >What prompted Bushnell to design his sub in this shape? Was
> >he pondering an egg while eating breakfast? Was he familiar
> >with that parlor trick [ and how old is that parlor trick? ] :-)
>
> I'd bet the design comes from a barrel with a extension for weight
> (keel) to keep it upright. But we'll propably never know ...
>
You're probably right. Perhaps Bushnell was pondering a "barrel"
of ale while imbibing a pint at the local tavern?
>
> The perfect pressure vessel shape is still the ball.
> Egg has other functions that affect its shape.
> - It has to be taken out of the chicken (or lizard or ...)
> without harming the "host".
Ouch! Yea, a square egg would hurt.
>
> >So...does anyone know the crush depth of an egg?
>
> Empty, boiled or raw ;)
Ideally, empty, but the holes needed to evacuate the yolk and albumin
would skew the test since they would produce micro fractures.
> 110m would propably be the crush depth of an empty egg.
> Because most of the load on the egg when using point load
> is affecting via the shell it self.
>
Well, the only way is to do it myself! Next time I'm on a lake or
at the ocean I might give it a try. I think there are surface mounted
strain gage tapes that could be placed on the egg to detect the
moment an egg would crack/implode. I'll get out my fishing pole
and reel.
Now..how about a Klein Bottle for a sub hull. What is the crush
depth and where would you sit? ; )
Thanks, --Steve