Discuss the effects of applying a torsional loading to a long straight member?

Torsional Loading causes the deformation of the straight member about its longitudinal axis.

It is characterized by the amount of torque, angle, and direction of the application of torque.

Hence if the amount of torque and angle of twist(rotation) is small, then there is no effect in the radius of the shaft. But if it is large then the radius decreases.

   The torque equation is

 $$\begin{gathered} \frac{T}{J}=\frac{\tau }{R}=\frac{G\theta }{L} \\ T= Torsion \\ J = Polar Moment of inertia \\ \tau = Shear Stress \\ R = Radius of Shaft \\ G = Modulus of Rigiidity \\ \theta = Angle of twist \\ L = Length of shaft \end{gathered}$$