Question

Derive the torsion equation for a circular shaft of diameter d subject to torque T

Answer 1

Loaded shaft ha a  deformation in the body, and  energy  stored in the body is called  strain energy.basic definition of the strain energy:  

Strain energy is  defined as the internal energy stored in the body when body will be subjected with a load within its elastic limit.

We must ensured that load applied over the body must be within its elastic limit ; body must secure its original dimensions.