Torsion testing is widely used in industry to study mechanical performance of materials in rod form. Figure Q3 below shows a sketch of a bulge test. Torque, T Length, Torque, T Figure Q3. Diameter, D Twist angle. Torsion test set up of a cylindrical rod d Derive the relationship for shear stress on the surface T, as shown below (15 marks) B 4 kN 2m