A rod is made from two segments: AB is steel and BC is brass. It is fixed

Question:

A rod is made from two segments: AB is steel and BC is brass. It is fixed at its ends and subjected to a torque of T = 680 N ˆ™ m. If the steel portion has a diameter of 30 mm, determine the required diameter of the brass portion so the reactions at the walls will be the same. G_st= 75 GPa, G_br= 39 GPa.

1.60 m 680 N-m 0.75 m