1. Lecture Series on Strength of Materials-5
“Moment of Inertia”
By Ashish Ravindra Lande M.E(CADME) Lecturer at Department of Mechanical Engineering K.K.Wagh Polytechnic, Nashik

2. Basic.. Centre of Gravity
It is defined as the point through which whole weight of body supposed to be act.
Centroid or Centre of Area.
It is defined as the point through which whole area is assumed to be concentrated.

3. Moment of Inertia
It is defined as the algebraic sum of product of area and the square of distance from the particular axis.
It is denoted by Ixx or IYY
It is given by I=Ah2
Unit- mm4.
It is second moment of area which is measure of résistance to bending & forms basic to strength of material.
Mass MI is the résistance to rotation & forms basic to dynamics to rigid bodies.

4. Radius Of GYRATION
It is defined as the distance at which area is supposed to be concentrated for same moment of inertia.
It is denoted by K.
It is given by ;I= Ak2 K= (I/A)1/2
Unit-mm.

5. Mi of Simple section

6. Mi of Simple section

7. Parallel axis Theorem.
M.I of plane section about any axis is equal to MI of plane section about the parallel axis parallel axis passing through its CG plus the product of area and square of distance between two axes.

8. Perpendicular axis Theorem
The moment of inertia of polar axis is equal to algebraic sum of MI of two axis about which axis is perpendicular.

9. Composite section

10. For Un-symmetrical I SECTION

11. MI of Composite section

12. MI OF Symmetrical I Section

13. Thank You