How Do You Calculate the Moment of Inertia for a Tapered Tube?

AI Thread Summary
To calculate the moment of inertia for a tapered tube, one must first determine the areas of both ends using the formulas AL=2*pi*RL*t and AS=2*pi*RS*t. The area at a distance x along the tube is given by AX=2*pi*RX*t, where RX is defined as RL - x*tanalpha, with tanalpha being the ratio of the change in radius to the length of the tube. A key distinction is made between calculating the second moment of area (units of L^4) and the mass moment of inertia (units of ML^2), as each serves different purposes in analysis. The discussion also touches on calculating the second moment of area for circular sections. Understanding these calculations is crucial for accurate structural analysis of tapered tubes.
Sud89
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Homework Statement


To calculate the moment of inertia of a cantilevered tapered tube with mid-thickness large radius RL and mid-thickness small radius RS

Homework Equations


upload_2015-11-9_19-52-48.png


The Attempt at a Solution


Area of the larger end of the tube
AL=2*pi*RL*t
Area of the smaller end of the tube
AS=2*pi*RS*t
Area of the tube at a distance x is
AX=2*pi*RX*t
RX=RL - x*tanalpha
tanalpha=deltaR/L
deltaR = RL-RS[/B]
 

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When you say 'calculate the moment of inertia', do you mean calculate the 'second moment of area' of the cross section of the tube (units of L4 ) or do you mean calculate the 'mass moment of inertia' of this piece (units of ML2 )? It makes a difference ...
 
SteamKing said:
When you say 'calculate the moment of inertia', do you mean calculate the 'second moment of area' of the cross section of the tube (units of L4 ) or do you mean calculate the 'mass moment of inertia' of this piece (units of ML2 )? It makes a difference ...

Second moment of area
 
Sud89 said:
Second moment of area
How would you calculate the second moment of area for a circle?
 
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