What Is Moment of Inertia?

The moment of inertia of an area is a geometric quantity and is usually used to describe the resistance of a section to bending. The SI unit of moment of inertia is (m ⁴ ). That is, the area second moment, also known as the area moment of inertia, and this concept is different from the mass moment of inertia (that is, the moment of inertia). ^[1]

The product y ² dA or z ² dA of the area element dA and the square of its distance from the z-axis or y-axis is called the moment of inertia of the area element for the z-axis or y-axis or the quadratic axis moment of the section, respectively. The value of the moment of inertia is always greater than zero

Moment of inertia for Z axis:

Static moment (area X axis in the plane once)

The relationship between section moment of inertia and polar moment of inertia.

The sum of the moments of inertia of the section to any pair of mutually perpendicular axes is equal to the polar moment of inertia of the section at the intersection of the two axes Ip = Iy + Iz.

Where I _y and I _z are the moment of inertia of the section against the coordinate axis, I _yz is the inertia product of the section and the coordinate axis; I _yc and I _zc are the moment of inertia of the section and the centroid axis, and I _yz is the Product of inertia; a, b refer to the distance from the centroid to the y-axis and z-axis, respectively; A refers to the cross-sectional area.