Bending Moment

Definition - What does Bending Moment mean?

The bending moment is the moment when the maximum stress is equivalent to the ultimate strength of the material and failure occurs. When the bending moment is large enough, plastic zones develop in a structure made of an elastoplastic material.The beam is the most common structural element that is subject to bending. The bending moment prohibits the sagging deformation characteristic of a beam experiencing bending.

The bending moment concept is very crucial in civil & mechanical engineering, and in physics. It is used to calculate where the largest amount of bending takes place.

Corrosionpedia explains Bending Moment

The bending moment tends to bend the beam. It is the product of force and perpendicular distance. Shape change or deformation due to the bending moment can be measured by the curvature of the neutral surface.

When the bending moment is enough to induce tensile stresses greater than the yield stress of the material throughout the entire cross-section, bending failures occurs. In structural analysis, this failure is known as a plastic hinge. Although failure in shear and in bending mechanisms are different, failure of a beam in shear may occur before failure in bending.

In a bending moment diagram, critical values within the structural element are usually annotated where negative moments are plotted to scale above a horizontal line and positive moments below. This moment varies linearly over unloaded sections, and parabolically over uniformly loaded sections.

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