Fatigue Tests and Aircraft Life Evaluation: On the Experimental Correlation of Service Endurance Tests with Fatigue Tests at Constant Stress Amplitude

THE method used at present in fatigue testing aircraft joints and components by applying cycles of constant stress amplitude of a magnitude considered to be the most damaging is based on the assumption that Miner's cumulative damage rule, Σ(n/N)&equals l, holds good. This rule is known to be true only under certain conditions which may not apply to those under which fatigue damage is accumulated in aircraft.