고체역학 (Gere) — Torsion: Problem 3.3-19

3.3-19 A solid brass bar of diameter \( d = 30 \text{ mm} \) is subjected to torques \( T_1 \), as shown in part a of the figure. The allowable shear stress in the brass is \( 80 \text{ MPa} \). (a) What is the maximum permissible value of the torques \( T_1 \)? (b) If a hole of diameter \( 15 \text{ mm} \) is drilled longitudinally through the bar, as shown in part b of the figure, what is the maximum permissible value of the torques \( T_2 \)? (c) What is the percent decrease in torque and the percent decrease in weight due to the hole?