GATE 2017 ME (ME2) – Question 21
A ductile machine component has minimum and maximum stresses −50 and 50 MPa. Its corrected endurance limit is 100 MPa and yield strength is 300 MPa. The factor of safety is ______.
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Correct answer: 1.99 to 2.01
Explanation
Mean stress is(50−50)/2=0 and alternating amplitude is(50−(−50))/2=50MPa. For fully reversed loading, fatigue safety factor is corrected endurance limit divided by amplitude:100/50=**2**. Yield safety factor300/50=6 is larger, so fatigue governs.