At 02:39 PM 2/3/2000 -0600, you wrote:
>Hey Mike,
>
>Without measuring the shafts and calculating the second moment, there is
>no way to say which shaft is easier to accelerate. You could be right
>that the aluminum shaft still comes out ahead despite a thicker wall,
>but the OD is really quite a bit more than the steel, which levels the
>playing field again. In the calculations for inertia:
> 4
> (pi) x density x Length x (Outside Radius-Inside Radius)
>I= ---------------------------------------------------------
> 2
>
>The R is the shaft radius, density is material density, Length is shaft
>length, I is inertia about the central axis. You can see that Radius is
>to the 4th power which makes it 4 times more critical to the inertia as
>does the material (density).
>
>As per usual, anybody whose brain is full, head hurts, or brain exploded
>messily may be excused.
>
>Cale
Ok, I like it. Next question, what is the density index of steel and
aluminum. I see your point. Makes perfect sense - even though the
material is lighter, making the diameter larger reduces the advantage of a
lighter material.
Good stuff
Mike
__________________________
mschwall@flash.net
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