A Prismatic Bar (Diameter $d _ { 2 } = 25 \mathrm {~mm}$

Multiple Choice

A prismatic bar (diameter $\text { (diameter } d _ { 0 } = 18 \mathrm {~mm} \text { ) is loaded by force } P _ { 1 } \text {. A stepped bar (diameters } d _ { 1 } = 20 \mathrm {~mm} \text { and }$ $d _ { 2 } = 25 \mathrm {~mm}$ with radius of fillets $R = 2 \mathrm {~mm}$ ) is loaded by force $P _ { 2 }$ . The allowable axial stress in the material is $75 \mathrm { MPa }$ . 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