Fatigue Damage Accumulation and Testing for Performance Evaluation.

The effect of mean stress and of stress amplitude on the various stages of the fatigue process is discussed in the light of recent research on fatigue mechanisms with the purpose of assessing the relevance of fatigue testing processes under constant and under random loading as well as of the application of linear fracture mechanics in the prediction of the fatigue life of airframes. It is concluded that fatigue tests based on a mission-determined representative flight-by-flight loading spectrum will produce the closest approximation of service conditions and should be used both for life prediction of structures and for materials evaluation for fatigue performance. Author