I'm finishing up a project and am having trouble with the analysis.

I bent bones and broke them and am trying to calculate the ultimate tensile stress. The bones are oddly shaped, so I can't use a simple equation for the area moment of inertia i.e I=pi*r^4/4. I have pictures that I've converted to binary B&W images and can calculate the cross sectional area, but I need to calculate the second moment of area (area moment of inertia) in order to correctly calculate the max stress. If anyone can help guide me it would be very much appreciated. I've been working on this for weeks.

"Harry" wrote in message <ie3i9k$24d$1@fred.mathworks.com>...
> I'm finishing up a project and am having trouble with the analysis.
> 
> I bent bones and broke them and am trying to calculate the ultimate tensile stress. The bones are oddly shaped, so I can't use a simple equation for the area moment of inertia i.e I=pi*r^4/4. I have pictures that I've converted to binary B&W images and can calculate the cross sectional area, but I need to calculate the second moment of area (area moment of inertia) in order to correctly calculate the max stress. If anyone can help guide me it would be very much appreciated. I've been working on this for weeks.

Hi Harry,
did you solve your problem ? If your image is well oriented along the X,Y direction, a good way is 
i - compute the barycenter position XM, YM
ii- compute the sum of the (Y-YM)^2 to extract the quadratic moment (sectional inertia)

I wrote a macro for ImageJ but if you wrote a code for Matlab, I am interested in.

Eric