The 48-in bar has a solid circular cross section with 4-in diameter. The shear modulus G = 4E6 psi and the yield stress τ Y = 60, 000 psi. Model the material as elastic-perfectly plastic. What are the...

The 48-in bar has a solid circular cross section with 4-in diameter. The shear modulus
G
= 4E6 psi and the yield stress
τ
_Y
= 60, 000 psi. Model the material as elastic-perfectly plastic. What are the external torque
T
and the bar’s angle of twist (in degrees) if
r
_Y
= 1 in?