Flight parameter based fatigue analysis approach for a fighter aircraft

This paper describes a flight parameter based fatigue life analysis approach, which is developed for the Finnish Air Force F-18 fighters. It produces a flight specific fatigue life estimate for structural details using flight parameter data stored by each aircraft. Artificial neural networks are used to model structural response of analyzed details as a function of flight parameters. The analysis development is based on strain gauge data from 25 flights of an instrumented aircraft. The results show a satisfactory accuracy for the fatigue life estimates and prove the concept level analysis capability. The average difference between measured and modelled fatigue life is 21% for the fuselage bulkhead and 30% for the leading edge flap's hinge area. The total differences in the Finnish Air Force average usage are extremely small, being -2% for the bulkhead and +2% for the leading edge flap.