A Prismatic Bar (Diameter $d_{0}$ = 18 Mm) Is Loaded by Force

A prismatic bar (diameter $d_{0}$ = 18 mm) is loaded by force $P_{\mathrm{1}}$ A stepped bar (diameters $d_{1}$ = 20 mm and $d_{2}$ = 25 mm with radius of fillets R = 2mm) is loaded by force $P_{2}$ . The allowable axial stress in the
Material is 75 MPa. The ratio $P_{1} / P_{2}$ of the maximum permissible loads
That can be applied to the bars, considering stress concentration effects in
The stepped bar, is: (A) $0.9$
(B) $1.2$
(C) $1.4$
(D) $2.1$

FIG. 2-66 Stress-concentration factor K for round bars with shoulder fillets.
The dashed line is for a full quarter-circular fillet.