Report a Question

Explanation

This problem is easiest to solve using Mohr's circle.

Torsional loading for a circular bar generates a plane stress, pure shear state of stress on the surface of the bar. For pure shear the normal stress will be zero for the orientation of the stress element at which the maximum shear stress occurs. The maximum shear stress is equal to 100 MPa, which defines the radius of the circle.

This allows us to draw Mohr's circle for this stress state, which is shown below.

The minimum principal stress ${\sigma }_2$ is therefore equal to -100 MPa.