What is Second Moment of Area?
The second moment of area measures a beam’s ability to resist deflection or bending over a cross-sectional area. It is also known as the area moment of inertia. The second moment of area is used to predict deflections in beams. It is denoted by I and is different for different cross sections, for example rectangular, circular, or cylindrical. The unit for this measure is length (in mm, cm, or inches) to the fourth power, i.e. mm4 or ft4. The most common units used in the SI system for second moment of area are mm4 and m4. Mathematically, the second moment of area can be written as, Ix = integral (y2 dA) Iy = integral (x2 dA) where, Ix is the second moment of area about x-axis, Iy is the second moment of area about the y-axis, x and y are perpendicular distances from the y-axis and x-axis to the differential element dA respectively, and dA is the differential element of area. The area moment of inertia for a rectangular cross section is given by, Ix = bh3/12, where b = width and h = hei
