6. A shaft is fixed to a wall at one end, subjected to a torque T', as shown in fig. 5. The shaft is made of steel with the following properties: E-250 GPa, v = 0.33, and L = 5m. (a) Determine the largest permissible cross-section a x b of the steel shaft, for the shearing stress not to exceed 120 MPa, while the shaft is twisted through 11. Assume the aspect-ratio of the cross-section, 1.e. the relationship between a and b, to be a = 2.56. (b) In a diagram, indicate the location of maximum stress. Note: Table 2 is provided for reference. Figure 5 Solution: (a) a 85.5mm, b=34.2 mm. (b) Along middle line of top and bottom sides.