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Ascetic Anchorite
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Does anyone know how to calculate the moment of inertia of a frustum? I need to workout the MOI of a taper, as in tapered cylinder bearings.
Just as the cone in the picture below, the taper (frustum) is uniform and revolving about its longitudinal axis:
I have found a couple of equations but I have nomenclature issues with them and I do not fully understand how to use them.
This is the main ‘solution’ I found:
http://answers.yahoo.com/question/index?qid=20060804212218AA5Ma9R
There is a link to a RapidShare word file through that link that should explain it better, but my ISP (NTL) uses proxies and RapidShare therefore refuses to allow me to download anything from their site!
Any help appreciated.
Just as the cone in the picture below, the taper (frustum) is uniform and revolving about its longitudinal axis:
I have found a couple of equations but I have nomenclature issues with them and I do not fully understand how to use them.
This is the main ‘solution’ I found:
Consider a disc of thickness dy as a section of the cone. The moment of intertia of that disc depends on the vertical coordinate y and is
I(y)*dy ={ integral[r=R0 to r= R0-(R1-R0)(y/h)] of m*(r^2)*(2*pi*r)*dr }*dy
After integrating that, the overall moment is
I = integral[ y=0 to y=h] of i(y)dy
h = height of the frustrum
R0 = radius of the base
R1 = radius of the top
m is density of the cone material
Edit: I have worked this out, but it is very complicated with lots of chances for numerical error. My tentative solution (until I check for numerical errors) is:
I = (pi/10)*m*h*[26*R0^4 - 49*R0^3*R1 + 21*R0^2*R1^2 - 9*R0*R1^3 + (R1^4)]
http://answers.yahoo.com/question/index?qid=20060804212218AA5Ma9R
There is a link to a RapidShare word file through that link that should explain it better, but my ISP (NTL) uses proxies and RapidShare therefore refuses to allow me to download anything from their site!
Any help appreciated.