Understanding Stresses in Beams

In this video we explore bending and shear stresses in beams. A bending moment is the resultant of bending stresses, which are normal stresses acting perpendicular to the beam cross-section. We can easily derive an equation for these bending stresses by observing how a beam deforms for a case of pure bending. This equation is know as the flexure formula.

Next we look at shear stresses, which act parallel to the beam cross-section, and can be represented by a shear force. These vertical shear stresses can cause horizontal shear failure in beams, because they result in complementary horizontal shear stresses, which develop to maintain equilibrium.

Finally we look at how we can apply the shear stress equation to thin-walled open sections like the I beam, and how shear stress appears to "flow" through the cross-section.

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ERRATA:
- The moment shown at 07:38 is drawn in the wrong direction.
- The shear stress profile shown at 11:41 is incorrect - the correct profile has the maximum shear stress at the edges of the cross-section, and the minimum shear stress at the centre.

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The Efficient Engineer is a channel aimed at mechanical and civil engineers. The mission is to simplify engineering concepts, one video at a time!

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