Second moment vs. Mass moment of inertia

[Teunis]

In my CAD software (Alibre) I can only calculate the mass moment of inertia of a given part.

I need the second moment of inertia. I know I should go through my theory books, but maybe you could help me :

Can I "convert" my mass moment of inertia to the second moment of inertia ?

regards,
Sander

 

[EnglishMuffin]

The correct term is "second moment of area", not "second moment of inertia". And theoretically, no you can't, unless the "part" happens to be a plane lamina of zero thickness, which would not be a physical object of course. However, if you modeled a solid but very thin part of uniform thickness, it would be possible to approximate the second moment of area of the part's surface about an appropriate axis by dividing the part's mass moment of inertia by the product of it's thickness and mass density. I think this question has been asked several times before.