Re: neutral axis of a non-symetrical shape

On Apr 6, 6:15 pm, Adam <n...@xxxxxxxx> wrote:
On Sun, 6 Apr 2008 05:40:13 -0700 (PDT), Adam Chapman wrote:
I remember that it is very easy to find the neutral axis of a
symmetric beam cross-section, just locating the centroid and
intersecting a line of symmetry.

However, I want to find the neutral axis of an area which is non-
symmetrical. Does anybody know off-hand what to do?

I am tryingto use the principle in image processing- if i see an
object which can be rotated through any angle 0-360 degrees, i want to
find the neutral axis of the object and rotate the image to attenuate
inaccuracy in my recognition algorithm.

If anyone has a link that would be great, all i can find on google is
symemetric examples- doh!

Thanks for any help, it is greatly appreciated.
Adam

http://www.google.com/search?hl=en&q=%22neutral+axis%22+bending+centroid

http://physics.uwstout.edu/StatStr/statics/Beams/bdsn47.htm

        the neutral axis (an axis running
        through the centroid of beam cross section).

just locating the centroid and
intersecting a line of symmetry

Why locate an "intersecting a line of symmetry"?

The moment of inertia with respect to a line parallel to the axis of
bending will change as you rotate the shape.  Does that matter in your
application?  Are you searching for an orientation to minimize (or
maximize) that moment of inertia?

How does beam flexure theory relate to image processing?

Adam

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Im making a character recognition algorithm, and my camera could see
alphabetic characters rotated about any angle.
My inputs to the recognition algorithm are effectively the moments of
inertia of the black pixels that make up the image of the character.
The problem I have is that, like you said, the moments of inertia
change with rotation of the shape. I think recognition accuracy could
be improved by finding a neutral axis and rotating the black pixel are
to line up that axis will improve accuracy.

Sorry the only examples of neutral axes that i have studied in
mechanics about 3 years ago were all for symmetrical beam sections.
.

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