A stepped shaft ABCD consisting of solid circular segments is subjected to three torques, as shown in the figure. The torques have magnitudes of 3000 N.m, 2000 N.m, and 800 N.m. The length of each...

A stepped shaft ABCD consisting of solid circular segments is subjected to three torques, as shown in the figure. The torques have magnitudes of 3000 N.m, 2000 N.m, and 800 N.m. The length of each segment is 0.5 m and the diameters of the segments are 80 mm, 60 mm, and 40 mm. The material is steel with shear modulus of elasticity G = 80 GPa.

(a) Calculate the maximum shear stress t_max
in the shaft and the angle of twist

_D
(in degrees) at end D.

(b) If each segment must have the same shear stress, find the required diameter of each segment in part (a) so that all three segments have shear stress t_max
from part (a). What is the resulting angle of twist at D?