Thu, 03 Feb 2000 17:58:53 -0600
>
>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
>
Depends on the aluminum, typically about 1/3 but it can be almost equal....
-- dave______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com
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