A Comparison of Fatigue Lives under a Complex and a Much Simplified Flight-by-Flight Testing Sequence.

This Australian report describes Flight-by-flight fatigue tests which were carried out on specimens representing part of the front flange of the main spar of the Mirage III wing. Two loading spectraloading sequences were used, the first being a 200-flight sequence incorporating 24 different types of flight developed by the Eidgenoessisches Flugzeugwerk in Switzerland and the second a much simplified 100-flight sequence incrporating only 4 different types of flight developed by Avions Marcel Dassault in France. The fatigue tests showed that there were no significant differences in the lives to failure between specimens tested under the two sequences, and it was therefore concluded that use of the simplified stress spectrumsequence would not have invalidated the findings of a previous investigation to develop life-enhancement procedures for the Mirage wing main spar. Keywords include Fatigue materials, Bolted joints, Cold working, Fasteners interference, Aluminum alloys, and Load spectra.