Area Moment of Inertia - Annulus Cross Section
The second moment of area, also known as moment of inertia of plane area, area moment of inertia, polar moment of area or second area moment, is a geometrical property of an area which reflects how its points are distributed with regard to an arbitrary axis.
The second moment of area for a shape is easier to be calculeted with respect to a parallel axis or with respect to a perpendicular axis through the centroid of the shape.
The formula calculates the moment of inertia of a filled annulus cross section with inner radius r1 and outer radius r2 with respect to a horizontal axis through the centroid of the annulus, parallel to the shape. (Parallel axis theorem)
|Area Moment of Inertia (mm4)
|outer radius of annulus (mm)
|inner radius of annulus (mm)