Forces that are acting perpendicular to the longitudinal axis of the beam cause bending stresses which are termed as flexural stresses, beside flexural stresses beams also undergo shear stresses and normal stresses.

We know from the basic concepts of internal forces in the beams that whenever some load either dead load, live load, imposed load, superimposed load or whatever is applied, it produces some internal forces and resultant stresses within the fibers of the beam. These internal forces within the fiber includes, Bending Moment M, Shear Forces V and normal forces P.

Bending Moment as the name suggests is a bending force that is caused as a result of the moment of the force given by the magnitude of the force multiplied by the distance to the point of consideration along the length of the beam. Bending moment varies throughout the length of the beam and is thus given by a diagram called Bending Moment Diagram.

Therefore it is concluded that the Stresses that are caused as a result of bending is called flexural stresses.

In order to calculate flexural stresses there is a very well-known formula called flexural formula. Flexural formula is derived while considering some assumptions which are as follows :-

1. plane section of the beam normal to its longitudinal axis prior to loading remains plane after the forces and couples have been applied,

2. the beam is initially straight and of uniform cross section

3. the moduli of elasticity in tension and compression are equal.

2. the beam is initially straight and of uniform cross section

3. the moduli of elasticity in tension and compression are equal.

α = My/I

Where α = Flexural Stresses

M is the bending moment at any point along the longitudinal axis of the beam

Y is the internal fiber distance from neutral axis

I is the moment of Inertia of the Beam

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