Influence of Load Cycle Reconstitution on Fatigue Behaviour

摘要

Fatigue experiments have been conducted to assess the influence of the method of reconstituting a load sequence from a range-pair counted load spectrum for a fighter aircraft. In addition to the original flight-by-flight sequence, several quite-structured reconstituted sequences and random reconstituted sequences were used, all sequences having identical range-pair counts. There was little or no difference in crack propagation lives or total lives of two specimen geometries for the several structured sequences which were designed to give the extremes in crack growth life. There was, also, no significant difference in crack propagation lives for specimens tested under the flight-by-flight and random sequences. Crack growth under the more structured sequences was significantly slower than under the more fluctuating sequences (random and flight-by-flight), though the maximum difference of 1.59:1 is small relative to other uncertainties in fatigue life assessment. These results provide a basis for implementing the Aircraft Fatigue Data Analysis System which utilizes strain range-pair counting.