Chapter 14.2, Problem 14.14P

Consider the thin-walled tube of Fig.5-26 . Use the formula for shear stress, τ_avg = T/2t A_m, Eq.5-18, and the general equation of shear strain energy, Eq. 14–11, to show that the twist of the tube is given by Eq.5-20. Hint: Equate the work done by the torque T to the strain energy in the tube, determined from integrating the strain energy for a differential element, Fig.14–4, over the volume of material.