Explain tangential or shearing stress and shearing strain

Explanation

In figure if two equal and opposite deforming forces are applied to the cross-sectional area of the cylinder and there is relative displacement between the opposite faces of the cylinder.
The restoring force per unit area developed due to the applied tangential force is known as tangential or shearing stress.
As a result of applied tangential force, there is a relative displacement Ax between opposite faces of the cylinder as shown in figure.
Due to this, the strain so produced is known as shearing strain and it is defined as the ratio of relative displacement of the faces to the length of cylinder L
`epsi _(0) = (Delta x)/(L) = tan theta =theta`

Where`theta` is the angular displacement of the cylinder from the vertical. Usually`theta` is very small, tane is nearly equal to angle `theta`
A body subjected to shearing stress is shown in figure. When a book is pressed with the hand and pushed horizontally, vertical side makes small angle with horizontal.