PARAMETER BASED FATIGUE LIFE ANALYSIS FOR F-18 AIRCRAFT

摘要

A flight parameter based fatigue life analysis has been developed for structurally critical details of the F-18 aircraft. The analysis uses as an input the data stored from the standard aircraft flight control system on each flight allowing individual aircraft fatigue tracking. The stored data is used to model stress history of the structurally critical details by using artificial neural networks. In the analysis development phase, flight measurement data from 22 flights of an operational loads measurement aircraft has been used. That data included strain gauge responses near analysed details. Results of a fuselage bulkhead, wing front and rear spars and vertical tail attachment area are presented in this paper showing a useful accuracy for an aircraft operator. The average errors in predicted fatigue life for a set of nine flights were: bulkhead 15%, wing front spar 28%, wing aft spar shear tie 38% and vertical tail root 187%. The errors in the damage for the same set of flight were -13%, +17%, -24% and -3%, indicating that the largest modelling errors occur on flights with low fatigue life consumption and the errors compensate each others between the flights.