Principal Stresses and Strains MCQ with answer and solution

Concept

Definition of a principal plane

Step-by-step solution

1. A principal plane is a plane on which the shear stress is zero.

Explanation

By definition, principal planes carry only normal stress. The shear stress on them is zero and the maximum shear occurs on planes 45° away.

Why the other options are wrong

Shear stress on a principal plane is neither maximum nor related to the principal stress.

Shortcut

Principal plane = zero shear.

Common mistake

Confusing with the plane of maximum shear.