[Image of a shear stress diagram]

The shear stress diagram shows the variation of shear stress across a section of a beam. The shear stress is zero at the neutral axis and increases linearly to a maximum value at the top and bottom of the beam. The maximum shear stress is given by:

$$\tau_{max} = \frac{VQ}{It}$$

where:

* $\tau_{max}$ is the maximum shear stress

* $V$ is the shear force

* $Q$ is the first moment of area about the neutral axis

* $I$ is the moment of inertia

* $t$ is the thickness of the beam

The shear stress diagram is used to design beams for shear. The beam must be designed so that the maximum shear stress does not exceed the allowable shear stress for the material.