Shear Strain (Φ)

Angular deformation produced in member is called as "Shear Strain".
It is denoted by "Φ" (greek capital letter phi).

Consider a cube of side L subjected to two equal and opposite forces P on the top and bottom faces. Sence AB face is fixed, CD face shifted towards C'D' on appling load P as shown if fig.
Let,
X = shear deformation at right angle to the length L.
Now,

∴ Shear strain, Φ= ^X/_L