Tom Watson wrote:
> On Thu, 07 Aug 2008 20:38:33 -0400, Tom Watson <notme@[EMAIL PROTECTED]
>
> wrote:
>> It's like a woodworking application of the uncertainty principle.
>
>
> Please do not respond to me with posts that explain the workings of
> the actual uncertainty principle.
>
> It was an attempt at humorous analogy.
....
:)
Being a nuclear engineer/physicist by training, I'll refrain (w/
difficulty)... <vbg>
The actual is owing to the general test layout and the physics of plate
bending as noted in an earlier thread. If the material were actually
entirely uniform as we all know wood isn't, the bending stresses would
be perfectly symmetric and a solid piece of the same dimensions would
bend then break right down the middle.
There's a small effect at the edge owing to the discontinuity of the
fibers across the joint but w/ reasonably straight-grained wood it's a
secondary issue. The glue joint is, in fact, stronger than the breaking
strength and which side the test sample breaks upon depends on which
board has the weaker point flaw assuming even loading.
If you look at some of the web sides that have the "sagulator"
calculators for beam loading, some of them also have stress/strain
curves associated with them for various loading patterns. For
simply-sup****ted ends and point load in the middle, the bending moment
diagram is linear from the endpoints to the middle, then decreases in
the other direction to zero again at the other edge. Something like
Load
|
\|/
------------- Beam/panel
\ / -- 0 (zero bending moment)
\ /
\ /
\ /
\ /
\ / ------ M (max bending moment)
--
|
