GATE 2018 ME (ME2) – Question 31
For fully reversed loading, fatigue life follows $\sigma_a=1100N^{-0.15}$, where stress amplitude is in MPa and N is life in cycles. Find the maximum allowable amplitude for $10^5$ cycles (MPa), to two decimal places.
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Correct answer: 190.00 to 200.00
Explanation
Substitute the target life directly: $\sigma_a=1100(10^5)^{-0.15}=195.6107$ MPa. Thus **195.61 MPa**. Fully reversed loading has zero mean stress.