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RE: [PSUBS-MAILIST] Isn't 'Mini book review.' anymore--pressure t est
I had
never thought of doing this with the crew inside, but it might be possible.
There could be a number of factors that would affect air pressure, besides hull
compression (e.g. temperature, battery gassing, crew metabolism, scrubbing).
Perhaps one could do this:
- Take
all possible measures to reduce these effects. For example, have the crew use
rebreathers.
-
Observe the variation of pressure while operating at a constant shallow depth.
The idea is to see whether there is a constant factor, such as a gradual
increase or decrease of pressure per operational hour, while staying at the same
depth.
- Dive
while graphing pressure relative to depth, but not going too
deep.
If the
last step gives you a straight line indicating proportionality, you could keep
going down until you observed a deviation of the line.
But
darn, this is SO theoretical. What about a thermocline?
Alec
In einer eMail
vom 12.04.2002 17:30:52 (MEZ) - Mitteleurop. Sommerze schreibt
Asmyth@changepoint.com:
I'm referring to a thin tube that allows you to track air flow
out of the hull as the hull compresses.
Does that mean that the
proceed from the assumption that a hull with a whatever shape and a material
with a linear elastic behavior (for the first time) will contract under
external pressue with a linear increase of the inner pressure due to the
linear decrease of the inner volume? (if the hull is definitely sealed)
Hmm... sounds like a brilliant idea indeed.
With "stress gauges" (DMS
in german) there is the problem that you have to know were the critical
stresses will appear.
Tracking the decrease of the inner volume needs no
special consideration of the stiffeness distribution in the hull structure. It
works well even when the hull is really strong and only the hatch (or
something other) works like a drumhead.....
Unfortunately it doesn´t
work while the sub is manned... I guess that the fact that our lungs burns O2
to CO2 will also influence the micro-pressure..but I´m not sure about the
practical consequence. If you use also CO2 absorbers I´m relatively sure that
this will disturb any exact pressure tracking.
...maybe the passengers
have to brath consequently from a closed circuit (rebrather)
With this
procedure any nonlinear reaction to a linear increasing of the pressure will
be a sign for problem. increase the inner pressure with a higher ratio then
the deep ----> some parts of the structure got weak. If the inner pressure
increase continualy while the deep is the same there could be a leak an water
runs into the hull....
conclusion: very good method for preventing the
hull for demage or lose. But needs a fine deep sensor and a very fine pressure
sensor and a computer to get the curves in realtime.. or a quick pen ....
If wether it´s work in a boat on a lake or sea is just an other quest.
Thanks you for that good idea!
A.