Test: Analysis of Stress & Strain - 2 - Mechanical Engineering MCQ

The plane AB is principal plane, and at the principal plane shear stress is zero.

From the above figure coordinates of the centre are 

When the normal stresses on the two mutually perpendicular planes are equal and alike then radius of Mohr’s circle will be zero.
i.e.  

Hence Mohr’s circle reduces to a point.

The principal stress given are unlike i.e if one is tensile and other is compressive. Let σ₁ be tensile and σ₂ be compressive, then

Radius of the Mohr’s Circle 
Maximum shear stress, 
∴ Radius of Mohr’s circle is equal to maximum shear stress

Principal stresses,

Since minimum principal stress is zero, so

Mohr’s circle for pure shear stress

Since neither tensile nor compressive stress exists, the Mohr’s diagram is simply a circle of radius τ_xy and centre at the intersection of the two axes. It can also be verified by transformation of plane formula.

Maximum principal stress,