A Steel Bolt $\left( \text { area } = 130 \mathrm {~mm} ^ { 2 } , E _ { s } = 210 \mathrm { GPa } \right)$

Multiple Choice

A steel bolt $\left( \text { area } = 130 \mathrm {~mm} ^ { 2 } , E _ { s } = 210 \mathrm { GPa } \right)$ is enclosed by a copper tube (length = 0.5 m, area = $\left. 400 \mathrm {~mm} ^ { 2 } , E _ { c } = 110 \mathrm { GPa } \right)$ and the end nut is turned until it is just snug. The pitch of the bolt threads is 1.25 mm. The bolt is now tightened by a quarter turn of the nut. The resulting stress in the bolt is approximately:

A) $56 \mathrm { MPa }$
B) $62 \mathrm { MPa }$
C) $74 \mathrm { MPa }$
D) $81 \mathrm { MPa }$