GATE 2017 CE (CE2) – Question 53
A 2 m long, 8 mm diameter mild-steel rod is loaded in tension. Its load–elongation graph is shown. Yield stress is 250 MPa. Complementary strain energy in the linear-elastic range is ______ N mm.
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Correct answer: MTA
Explanation
The final key awards marks to all. In linear elasticity, complementary energy is $U^*=P_y\delta_y/2$. The stated diameter and yield stress give $P_y=250\pi(8^2)/4=12566$ N. Reading $\delta_y\approx2.5$ mm would give about 15708 N mm if the graph ordinate were newtons. It is printed in kN, inconsistent by a factor of 1000. No unique answer is imposed.