고체역학 (Gere) — Torsion: Problem R-3.15

R-3.15 A prismatic shaft (diameter \(d_0 = 19\) mm) is loaded by torque \(T_1\). A stepped shaft (diameters \(d_1 = 20\) mm and \(d_2 = 25\) mm with radius of fillets \(R = 2\) mm) is loaded by torque \(T_2\). The allowable shear stress in the material is 42 MPa. The ratio \(T_1/T_2\) of the maximum permissible torques that can be applied to the shafts, considering stress concentration effects in the stepped shaft is: (A) 0.9 (B) 1.2 (C) 1.4 (D) 2.1