GATE2018-2-21

Question

Fatigue life of a material for a fully reversed loading condition is estimated from $$\sigma_a=1100N^{-0.15}$$, where $\sigma_a$ is teh stress amplitude in $MPa$ and $N$ is the failure life in cycles. The maximum allowable stress amplitude (in $MPa$) for a life of $1 \times 10^5$ cycles under the same loading condition is ________ (correct to two decimal places).

Answer 1

Substituting the number of cycles for $N$

$1100*(1 \times 10^5)^{-0.15} = 195.61~MPa$