Effect of Spectrum Variations on the Fatigue Behavior of Notched Structures Representing F-4E/S Wing Stations.

摘要

This report presents the preliminary results of an experimental and analytical study of the fatigue behavior of structures subjected to flight-by- flight spectrum loading. The spectrum investigated was based on that applied to the lower wing skin of the F-4E Slatted Wing fatigue test article. Spectrum variations without changing spectrum content included peak load rank ordering, order reversal, peak load truncation and low load truncation. Spectrum variations including changing the spectrum content by changing the mission mix were also studied. The analytical prediction of low load truncation correlated well with the experimental results indicating that the contractor's truncation model adequately modelled the longer spectrum. The analytical predictions for the other basic variations without changing the spectrum content indicated that only a minor variation in fatigue behavior would be expected from spectrum reordering. Changes in the mission mix provided the most significant effect in fatigue behavior.